Flood Control and Water Conservation District - Regular Meeting

We're ready for roll call.

Member Condoff?

Present.

Member Chambone?

Present.

Member Garcia?

Present.

Chair Filipelli?

Present.

Let the record reflect member Cooper is excused.

Yeah. We can call for, public comment. Anyone who wishes to speak to the technical advisory group on such a matter, if it is not on the agenda, may do so at this time. At the discretion of the chair, individuals will be limited to a three minute presentation. No action will be taken by the technical advisory group as result of any item presented at this time.

Public comment is an opportunity for members of the public to speak on items that are not on the agenda, but are within the subject matter jurisdiction of the committee. Public comment is limited to three minutes per speaker subject to the discretion of the chair as previously mentioned. Comments should be brief and focused and speakers should be respectful of

one

another who may have different opinions. Please remember this meeting is being recorded and broadcasted live via Zoom. The county will not tolerate profanity, hate speech, abusive language, or threats. Also, while public input is appreciated, the Brown Act prohibits the committee from taking any action on matters raised during public comment that are not on the agenda.

Good afternoon. My name is Chris Malin. I'm the executive director of the Institute for Conservation Advocacy Research and Education. And I don't know if any of you got the email from the Department of Water Resources about the update to bulletin one eighteen. Public comment closed on Friday, and it was in draft.

I'm sure you're all quite familiar with it. It was a fantastic read and loaded of resources for groundwater monitoring and data points that are needed to monitor groundwater and the issues that are stressing the groundwater. Mainly, I just found it very informative of all the science, the new science out. Many, many different types of monitoring going on by the state. So I would recommend if you haven't that, that you do take a look at it.

And maybe even the county can, you know, maybe do a presentation on it, ask the state water resource the Department of Water Resource to come and talk about it. Quite substantive in its breadth and depth of information of the state of groundwater in the state of California. I did find it lacking in that it did not discuss the problems with water rights and water diversions and how that impacts groundwater. It's

not just the groundwater pumpers that are depleting the groundwater. It's the water diverters doing it as well. And in each county, there are surprisingly and shockingly a lot

of illegal water diversions going on. And that water is taken out of the the waters the the budget for groundwater, and nobody has their eye on that. And I just think that those renegade water diverters should be brought into the fold and start to own up for their illegal diversions and putting the water back and they're, you know, they're they're going ahead of everybody who does business the right way and goes through the process of getting water diversions and the application and the long wait and all of the science that has to go into whether or not they can divert or not and that they get away with that. The state doesn't have enough money to go after them with enforcement. So just wanna make that point.

Thank you. Do we have any other public comment in the room? Online?

We have no callers.

Thank you. Next item on the agenda is the approval of minutes from the September 11 meeting. Do I have a motion to approve? Second. All in favor? Aye.

Aye.

Thank you. And now I will pass it to Jamison for reports and announcements.

Yes. Have a Brendan and I both have a couple of reports and announcements, but this is also an opportunity for the TAG members to come forward with reports and announcements. So maybe while I'm you all can maybe you already have some things teed up, but if not, give you some time to think. First announcement is about our certification pilot program. This is something we've talked about a number of times over the previous months.

And we released a request for qualifications in October 20. Related to that program, we're looking for statements of qualification from individuals, entities, organizations, firms who might be able to partner with us, whether they be existing certification programs, vineyard and winery certification programs, or perhaps somebody who isn't but has ideas around that. We put together what we think is a relatively streamlined and simplified statement of qualifications packet, series of questions for people to answer. And the deadline is December 12. So that's tomorrow.

And we're looking forward to reviewing those proposals. We should be making completing our reviews the end of the second week of January, notifying potentially candidates who might have been selected in mid January, and hopefully getting going through the next couple steps to get anybody under contract by March. So if all goes well, that will be just in time for the new growing season and we can test out that program. Other update I'll just go ahead and jump to the fee study and then Brendan you can talk about CalSIP. Tuesday, two days ago, our Board of SupervisorsGroundwater Sustainability Agency did approve a resolution to adopt fees for groundwater users in the Napa Valley Subbasin.

The fees would not apply to anybody outside the subbasin, so the subbasin mostly comprises the valley floor for anybody who's listening and isn't sure. Of course, there were maps and other materials provided in that agenda item, but they did approve that. It won't go into effect until fiscal year twenty six-twenty seven. So the first checks, if you will, that anybody would be writing would be next year around this time, November, December 2020 We started the process in 2022. We've been working on it quite a while, but it still will have another year lead time for people to hopefully prepare.

Wrapped up and into the rates that were proposed in the full rate and fee study is the assumption not just an assumption, but actually documented that the county will contribute at least $500,000 toward the cost of the program and that the remaining cost would be divided and born among groundwater users. The board elected to determine every year at the time of budget adoption how much they would put in and it's entirely possible that they could contribute decide to contribute more than $500,000 in which case the rates that were published would be or the rates that would be actually put out would be lower than what was published in the rate and fee study. So for anybody looking at that or interested, those should be considered a ceiling that can't be exceeded, but it can be lower. So that's really all there is to say about that. Anybody who of course, our GSA board meetings are available for recorded and they're available online.

If anybody wants to watch that after the fact, the materials are published with the agenda. Just want to make that announcement. And then Brendan has one, too.

I guess, and following on that, the next steps on that are sending out some postcard mailers to the groundwater users in the sub basin that will be subject to the fee and possibly conducting some outreach to those folks via workshop or webinar to be determined, but sometime in 2026. A quick update on the CalSIP streamgage improvement grant that we received from DWR. As a reminder, there are five sites that were reactivating some historical USGS stream gauges that existed in the county at some point in time. Those five locations are Redwood Creek, Milliken Creek, Dry Creek, Conn Creek, and then Napa River at Calistoga. Currently, we're still in the design phase.

We are working through some of the logistics of figuring out how to integrate with flood controls, one rain units that exist at a number of these sites. And so we're really just trying to hone in and figure out what items need to be ordered, what modifications need to be made to those existing units to be able to start measuring stream flow. So I think we anticipate getting some of those designs and plans submitted for encroachment permits to the county and the city of Calistoga sometime this winter or early twenty twenty six. And I think installation should be around early twenty twenty six as well. And, yeah, that's it.

Thank you. As far as tag updates go, I personally don't have anything to share, anything from the rest of the group.

Yeah. Really quick. The Napa City has been involved with the California Sustainable for Ground Growing Alliance on a dry farming study. And part of that study, we have 16 vineyards between Napa, Mendocino, and Sonoma. And we have finished collecting the data, and we're just going through through the day and out.

So maybe by the next meeting, I can have a more formal report about this study. One of the things that we are seeing so far is that these dry farm vineyards in general tend to have greater water storage capacity. Just looking at comparing it to vineyards of similar soil texture. So that is to say that the way that these farms are are farmed, not only are they not irrigating, but when it rains, they there's a potential higher capacity to store and mobilize water. So that's very encouraging. There's other aspects of the study that we are going to be sharing with you guys, but I thought that was one note that excited me that I wanted to share with all of you. And maybe by the next meeting I'll have a more complete report about this study.

Thank you. Julia? No? Matt? No?

Nothing to contribute.

Thank you. Moving on to five a. I'll elect in the chair and vice chair for the next term. Jamieson.

Would anybody like to nominate themselves or someone else?

I think it's my turn.

What a champ. What a champ.

So I'd be

happy

to do it. Okay.

So you put forth yourself for chair. Anybody want to nominate themselves or another for vice chair?

I'm happy to stay as vice chair. It's okay.

Okay. So I think you have to take a vote on both those motions.

Motion to elect Matt Gandalf as chair. Do do they have to be two separate motions? Or No.

You can combine them.

And and Miguel Garcia as vice chair?

Second.

All in favor? Aye.

Aye. Aye.

K. We'll make it easy on you.

Aye. No.

Thank you.

Thank you very much. Next item, five b, is adopting our meeting calendar for 2026. Were we just looking for a motion?

Yeah. Did everybody see it? For a brief time we had an incorrect version on the website but this is the right one. So we're proposing meetings for March 12, April 9, September 10 and November 12. That's all factored around the development of the periodic evaluation which is due in January. But yeah, that's the calendar. Yeah, just motion and second and

Yep. Motion to approve the calendar.

Matt. I move.

All in favor?

Aye.

Aye. Aye. Aye. Alright. Thank you very much. Next up is doctor Andrew Mekelron with UC Davis to talk to us about great remote sensing atmospheric profile and about protrans piration experiment. Hi. Hi.

Well, thank you for the invitation. It's good to meet many of you in person and, good to be here to talk about the work that we've done in the past. So I'm a USDA scientist. I've been, with the Agricultural Research Service for about twenty years now and I'm also an adjunct professor in Viticulture and Enology. So we I just came down before this from the Oakville Experimental Station, so we actually have some, research sites there.

We're measuring things, on-site. So very interested in the watershed in general and, and these measurements. And I wanna tell you about the different tools that we've been using and developing over time, for measuring ET, both ground based and remote sensing, sensor systems. I'm here as part of a a really big team. So the GrapeX, team in particular, which was started by Bill Koustis, involves this is a small list of of those cooperators.

We've had sites across the state that I'll show you a bit later, but wanted to acknowledge that I am here representing a much larger group of people in in terms of the effort that's gone into this work. So the the GreatBags project, is people really wanted to to get a good acronym and forced it into this with with the extent of it. Ultimately, what it is is a large team project where we were assessing remotely sensed ET models. So so based on thermal satellite data from Landsat, it also incorporates other data. So the dyslexia and Alexi model that was developed by this, by Bill Kustis and the hydrology and remote sensing lab, this started in the nineteen nineties when they started building these models.

It has been ingested into the OpenET framework and it is one of the the six models there. So we've been working to ground truth this, doing a lot of measurements on the ground, and, when the satellites are flying over and and verifying how well the the sensor systems and the models are working in this way. So this is just an illustration of the types of things that we do. In the image there, you can see the EDI covariance towers that that are established on the right hand side there, which are really our gold standard, and I'll talk more about this. And then we send an army of people out on the days that we have a a drone flying over, which gives us much higher resolution, ET mapping capabilities, and at the same time, the the satellites are passing over in space.

And so we can actually see, with the drones, the people walking around the field as we're doing these measurements and and really linking these things across scale to make sure that we're most effectively modeling this appropriately. So as you know and as you've discussed a lot, there's lots of ways to measure and estimate ET. And so I'll go over several of these. You have soil soil water balance approaches similar to the potted plant on the right, as as many of you already think about this on your porch. Right?

You water it from the top. You can have drainage out of the bottom of that. You have runoff off of that system. We're really trying to from plant physiology perspective, trying to give the plants the right amount of water and not having other things pushed down through there. But there are reasons why drainage would be effective. And and as we're here talking about Sigma, is is very effective. So, you know, it's been done with weighing lysimeters. I've I've worked at the weighing lysimeter where the grapevines were were growing in the past. I'll talk a bit about calculated ET in the Symmis system, how we measure it directly with that eco variance and and that being our gold standard. But but really that there are some, some reasons that that you have to make adjustments with that data as well.

And then finally, the energy balance residual. And this is really all of the ground based sensing systems and the remotely sensed systems are using the same, approach of these energy balance, methods. And so we can both measure and model that, and then I'll talk about some other issues that come up when when you're using these approaches. So starting off with with Symmis is it's the one that has been used most widely developed by DWR scientists at UC Davis were involved in this. This is UNA UNFAO equation and and for us looking at grapevine evapotranspiration specifically.

And really that comes from how well a model grass or alfalfa would be doing under whatever those micro climatic conditions are that you're measuring and you need a crop coefficient for this. So we have these simis stations throughout the state. There's a a very pretty looking one there on the right hand side of that image of of being well maintained. And then we have to get the crop coefficient from somewhere and the ones for grapevines that are pertinent to the discussion here because the land is dominated by vineyard use in Napa was developed at the Kearny Ag Center in Parlier. This is down in the Central Valley.

It contained two Thompson seedless grapevines which are a raisin. They were table grape production but also raisin grapes. And they were growing in this for about fifteen years. So essentially, these are two potted vines that we were getting water use estimates for. And then that was translated to other places in the state.

So a professor at UC Davis, Larry Williams, developed a very simple but elegant method of of looking at the shaded area on the ground. So so the more radiation that is intercepted, you have more shaded area and that radiation is is what's driving the water loss from from the plant itself. That's what's driving that evaporation of water. And so you can see at the plot on the left hand side, the water use is strongly correlated with that shaded area and he developed crop coefficients for this. And this was translated all over the world.

People are using this in viticulture widely. And then he also did it for lots of different trellis types. So we see a lot of different ones here in Napa even and and how that can lead to different crop coefficients. But part of the problem with this, so when I first got here I started working on sap flow sensors on those two vines in the lysimeter. We were trying to extend it out and and see how well those were were being measured. This model, assumes that that plants are well watered. There's no stress in terms of nutrients. There's no disease problems. We have a lot of viral diseases here in Napa Valley that will impact water use and other things. And so it makes it different difficult to translate that data from those two vines there to the rest of the state.

So you need a stress coefficient which is also difficult to determine. And in general, CIMIS can give some problems. The stations are often not maintained particularly well and I'll show you a picture of Oakville here on the next slide. They're often located far afield from from where you're trying to make those estimates. As I said, it's difficult to develop those and determine the crop coefficients and it's ultimately translated from two grapevines of one variety in one location in the Central Valley.

So you can see some problems with that. I also included this because it's directly pertinent to a lot of the estimates that are going on for the modeling here in Napa Valley. So this is just time series of the Sima station at the Oakville station. This occurred after there was a transition of leadership at that position. Someone left and the irrigation got turned off.

This happens and Mark Batney is a farm advisor down in the Central Coast region and he has this great analogy as well too. He's given a talk that I've seen where he says, here are the sensors on a Sima station and he shows them that they're about the size of a quarter. He said these are the birds that visit the the Simus station and this is how large their feces is. And and so the average size of that is gonna cover if it goes to the bathroom on your sensor, it will cover that net radiation. So you have to take this data with a grain of salt and make sure that the sensors and and these systems are well maintained.

And this is just an example of of what can happen at some of these places. So taking into consideration with this. So moving on to the turbulent flux side of this. So so measuring with Eddy covariance. Everybody talks about this as the gold standard amongst biometeorologists and and we and the Grape X project have very extensive we've had as many as 20 of these stations throughout the state, and most of those were in vineyards at at one point.

So we have a lot of data for for the ground truthing of this and I'll show some later on, for the the northern this Northern Coast region in Borreli near Cloverdale. And the way that this works is it's measuring the wind speed and directionality as well as the the concentrations of gases. So it has an infrared gas analyzer on it that is measuring c o two and water. So it's actually measuring that water vapor that's being carried in those eddies, to that station. So in the cartoon on the top, it shows you that you have the tower on the right hand side of that and the wind is moving in a certain direction towards this.

And so it's representing the signal that you get at that tower is representing the land from where the wind blew across that. So in ideal conditions, you're doing this on large flat and homogeneous spaces. There's some of that in the valley floor here in in Napa, but oftentimes your hillsides, you have other sloping aspects that will impact that. You have a dynamic footprint, so where that wind is coming from will shift depending on wind directionality. So you have to account for these things.

And then in a lot of other sites, and I'll show you some data at the end, you can have additional heat sources that come into this that cause evaporation. So advection from hot dry grasslands or open areas will come in and actually cause more evapotranspiration and it affects the models. If you're not accounting for that, it can be problematic and you have to account for it in in the EDI covariance measurements as well too. Gonna actually skip this one. And the way that we account for that in the Eddy covariance is using thermal energy balance approaches.

So this is just based on the laws of thermodynamics. Energy can't be created or destroyed. So we know how much energy is coming into that system in terms of net radiation. The bulk of that is from the sun. And then the remainder of that goes into three compartments. It either goes into sensible heat flux. So the canopy and the ground heat up when they receive this radiation, for example. The wind comes along and then there's a gradient of temperature from the ground into that air and it gets carried away in the eddies. That's the sensible heat flux. A portion of it goes into the ground into storage, which is the ground heat flux.

And then the remainder of that energy goes into latent heat exchange. And so this is what causes evaporation of of the water from the system. Most of the methods, it difficult to measure the latent heat flux directly. It's much more expensive. And so that's what the Eddy covariance system allows you to do.

So most of the other methods for this are actually measuring the first three components and then backing out the latent heat exchange and calculating an ET. Even for the Eddy covariance systems, we actually use this approach to to account for how much energy could even evaporate water in the system and to make sure that what we're measuring for the gas concentrations actually makes sense physically with how much energy is available. And so that's why we use those. And then the other thing that I'll mention is that we're doing this both on ground, so with the towers in the the bottom right. But the same energy balance principles as I mentioned before are applied across scales whether it's drones, aerial planes or with the satellites.

It's the the same types of things that that they're doing here for it. So this is just a simple equation of of how we actually do adjustments to the turbulence flux. It's the energy balance residual there. So again, that I mentioned available energy is gonna be the net radiation mostly coming in from the sun, but all objects are radiating heat of some form. And and then you have a portion of that, so you're subtracting it off as going into the ground on a daily basis.

And then you have the turbulent fluxes. So they have that energy that was available and then you get that energy either being carried away by sensible heat flux or evaporating water from there, which is the latent heat flux portion of that. So this bone ratio that you may have heard about is the ratio of sensible heat flux to latent heat flux is an energy balance residual and it is used to adjust the turbulent fluxes and I'll show some data on this in in just a minute. I don't expect you to read this. I put this here just as an example of how many different methods there actually are for adjusting Eddy covariance measurements using energy balance residual.

And we have this in a recent manuscript and this is specific to vineyards that we did this for Grape X across a north to south transect of all these different sites. And so I can provide this paper with the citations in the in the upper left there and I'll show a bit of data from it. So when we're looking at this balance, so this is four turbulent fluxes measured with Eddy covariance which would be the the LE and the H on the y axis of these plots and then the energy that's available. So that's the net radiation and the the ground heat flux on on the bottom. This is essentially that balance that we're looking at.

And you're you're you're wanting this to be in an ideal situation if the turbulent flux measurements of Eddy covariance are actually working this would be a true one to one line. So the the b one which is the slope there would be one point zero as as opposed to point 7.75. So there is a closure issue here. So you have actually more energy available than there is that's showing up in in in the the fluxes itself. So you have to adjust that number and that's what's commonly done in this. So when people ask questions about are you closing the energy balance? Are you forcing closure with that? And what methods are you using? This is how that's going about being done. And we have a lot of data on that for for vineyard systems to do so.

This again, I don't expect you to read the x axis on this. This is from that previous table that I showed you of all the different methods for those adjustments. These are all different ways of adjusting that ET and how you can end up with different values. This is only for our site in Cloverdale. This is the closest site we have to here in Napa and I wanted to represent the the northern part of the state here.

And you can see that you end up with different estimates even using what is our gold standard depending on how you are adjusting according to that energy balance residual on there. But in general, they're all working pretty well to get towards that mean of of the red bar that they're going across it. So coming back to these thermal energy balance approaches, moving into sort of moving from the turbulence where we're measuring it directly with the ETI covariance systems. What we've also worked on and I should full disclosure here, Tom Shaplin, who apparently talked to your advisory group years ago, was my first PhD student. We work collaboratively with other scientists at UC Davis.

I'm on the patent for Thule Technologies, but as a federal employee, I have nothing to do with the company. My royalty checks are so small that that we don't even notice that they show up in the bank account. So full disclosure on that. I was involved in development of surface renewal as a commercial product but haven't been involved in the company since. So the idea that and and I think you're familiar with this but just to remind you with Tom is what Surface Renewal was trying to do was take a really expensive Eddy covariance system and try to get something out there that could measure this more effectively in a in a cheaper way.

And so the idea behind this is you have these air parcels which are represented by cubes here settle into a canopy, they heat up and they turn red and you get these these ramps of temperature increasing and then that air mass, its buoyancy changes and so it's gonna start floating and it gets replaced by another one. In the third image from the left, you have a cool air parcel coming in and ejecting that warmer air parcel and that happens over and over again. What Tom did, he's a really bright guy in math in his PhD was to figure out the signal. So the theoretical signal looks like these really clean ramps but the actual data looks like the bottom plot that I showed you there and he figured out where the signal was and where the noise was within this. And it eventually led to, the surface renewal part of this.

And so essentially going from a 10,000 or as much as a $100,000 equipment system with the ETI covariance depending on how you're measuring it to what you're all familiar with with Thule. So when I talk about surface renewal the rest of the time, it is the principles behind this of how of how this works and and some of the data that I'll show you. So we measured against the weighing lysimeter those original two grapes. We showed that surface renewal was working really well. We did it against water budgets with soil water budget as well too.

But then, you know, Tom left the lab, we, within the structure of GrapeX, actually looked at it relative to how it's done commercially. So in an ideal energy balance scenario, you're measuring net radiation sensible heat flux which is what Thule gives you, the ground heat flux and then you're calculating the ET. What they do in a commercial sense and the way to bring the cost down was to not measure net radiation and to model it and then to assume things about ground heat flux. So you're really using one component to estimate that LE from that. And so what the plot on the right hand side shows in the upper left, and sorry that's a little bit small, but this is the latent heat flux, so essentially that would be the ET.

And it shows that if you use the radiation from the tower and you use the ground heat flux measurements at the tower, you get a very nice one to one relationship. Surface renewal works really well when you measure everything. The rest of the plots, the right hand column is when you start to assume things about ground heat flux that it's zero on a daily basis which I could get into the theory if anyone has questions about that, but that's commonly done. And then when you model, so the bottom three sets of panels or three rows are when you start modeling net radiation and you can see that the data starts to spread and you start to get overestimation at the high ends of this if you're modeling net radiation. When you think of the modeling, the net radiation modeling that goes on throughout the state, it's a clear sky model.

It works really well for the Central Valley where we don't have clouds. I live in Davis and we don't have clouds from May all the way through October and it works very well there. For here with fog cover and other things, when you start modeling that radiation, you can start to diverge from from that value and it starts to creep in some uncertainty about that. That is full disclosure about I believe in surface renewal and proud of what Tom did, but also that depending on how you're measuring it, you can come up with different results in terms of how we actually use this data as as the standard here. So additional energy balance approaches that I wanted to talk about, we have since taken that that surface renewal.

We now use infrared radiometers to do this and this is part of what we're doing at the Oakville Station right now to measure the same types of things as what surface renewal is capable of doing and then having this feed into the model. And again, I can talk more about this at some other time, but we're looking to have these ground based sensors serving as anchors to go with the remote sensing to make sure that we're in the right ballpark for the types of measurements that we're getting in the estimates from that. So coming back to GrapeX, really what the ultimate goal of that was in the beginning was to ground truth these remote sensing methods and what those models are actually doing. So the Alexi Dyslexi one that's on the right hand side that's shown by the cartoon is essentially using the same thing. It's it's calculating an energy balance, calculating ET from an energy balance approach.

And so it is making some assumptions in there, but it is estimating sensible heat flux from the crop and it is, also using atmospheric temperatures and other things to map this. This is essentially the concept broadly that is used across all of the models that are in Open ET. There are different refinements of that and and different methods that they use slightly to get to that. But ultimately, it's dependent on the leaf area index, so how much leaf area is there to evaporate water and it's using the thermal signature of the land to estimate this using energy balance residual approaches. So we've measured all sorts of things.

We have some sites where we have a couple million dollars worth of equipment in it that we've done ad nauseam. This is a profile to better understand the atmospheric boundary layer and how those exchanges are going on. So we have done this over and above what you would normally do for evaluation of the system. As I mentioned, we did it in different trellising systems from a north to south gradient. So the one all the way on the upper left there of the large pixels that are right in the center would represent the region that we're in now in terms of what that looks like and across the season.

So this is some data from a 2019 paper from the original site that we worked at was in Lodi and this is showing how the observed ET, again with closure and unclosed conditions using the energy balance residual and under both situations with the dyslexia and Alexei model, it actually works pretty well. When you look at the graph on the bottom left that says site two with the red dots close to the one to one in terms of how the OpenET that this model that is embedded in OpenET is working. And then this is some of the unpublished data but I got permission from the author and collaborator on this to present this to you today of a new analysis that we've done over all of our data over a decade looking at how well this is working in the northern site, the center site and the southern site. So those are the scatter plots that are shown across the top and then under closed and unclosed conditions. And then the residuals, so this would be the difference between what we measure on the ground and what the open ET is measuring.

So how close are they going to be? When it's zero, those things are in equilibrium so they're showing the same thing. And you can see that there's some differences amongst those but in general, you see the mean for the open ET models across there. Most of those lie right along the zero line. So they're actually performing quite well.

There are situations, so if you look at the south plot in the upper right where you start to get this curvature of the line and it starts to skew off to the right where you have higher measured ET relative to what the open ET model is doing. So we have identified some situations and what's actually going on there, we believe is advection. So advection is when you have these big open grasslands that are next to a site. During the summer when there's no water in those grasslands and they're dried out, become an incredible heat source and when even standing beside this, you feel that heat moving towards you. We've actually measured the advection moving into both vineyards and orchard systems so the tower in the bottom right shows our advection tower capturing how much heat is moving off of that grassland and how much of it actually moves into the system.

And the data plot at the top actually shows the observed ET being higher than the model. So there's extra energy moving into the system that's causing additional evapotranspiration that the models are not picking up. So we are trying to account for this, recognizing the patchwork nature of that. How much of that is happening in Napa is a lot less. You don't see that curvature off in the northern plots that we have here in the same way.

But accounting for that, accounting for energy drainage of the hills here, cool air that moves down the hills and other things. There's other other types of things that will go on with the topography here in Napa Valley. And then this is just an example of of that same sort of advection of the ET and this is over multiple years from 2017 to 2025 in one of our sites. As you have these, the bottom plot there with the colors of yellow and oranges and reds show the drought monitor that is, from the University of Nebraska and we had the the big drought 2021, 2022 that goes up to 2023 there. And you can see in the very top plot, the blue line going much higher than the orange shows that we had high effective conditions.

So you had that grassland that was there, dries out, it becomes much hotter and a hotter heat source and it can start to skew your models at that point. So this is a plot to to, of Borreli, so this is up in Cloverdale where we've done these measurements. So this is to show that for when we've measured here in in this region, we have the small little wedge that is red there is the advective conditions. So most of the time that we're doing measurements in this region, we don't have these problems with the models. So in terms of what OpenET is seeing, it ends up being pretty realistic without these sorts of constraints.

And then this is my last slide that I'll show you here is also for this Cloverdale region. This is getting into the ET specifically for there. Across those three years, the plot on the left shows Eddy covariance in the black line. And then the Open ET model against that shows you the regression of those two. So a decent fit, but not exactly one to one but it's doing pretty well in terms of the model.

But really for the modeling that you're doing for hydrologic modeling, I think the third plot from the left is key. The Eddy covariance versus Open ET shows really good agreement between this data when you accumulate that over the season. So these things are lining up very well and you can see sort of that monthly comparison over on the right hand side of that. So we are feeling like the data actually works quite well here. There are some issues with the satellite data for when there is cloud cover.

You have latency issues with that of the return time of the satellites and how frequently that that you then do the data filling and we're working on that as well. And then this is the last plot that I'll show you here. This is surface renewal measurements at that same site and what can start happening when you're modeling net radiation there in that way and not actually measuring it directly and you can get much higher values from the surface renewal relative to the Eddy covariance in these conditions and we've seen that. And again that cumulative plot, the third from the left, really shows how much higher the surface real renewal can be at certain sites. So this goes back to those plots that I was showing you that when you measure everything, effectively on-site with each of the energy balance components, surface renewal seems to work very well.

But as you start to do some of these models in the assumptions, you can you can start to get a skew from that. So I will finish with that and happy to take any questions. And sorry if that felt like a lecture. Okay. Great.

Thank you. Any questions to start off with? Comments? Yeah. A lot of information.

Yeah, are just thinking. For the presentation. One thing and I don't know how much interaction or kind of understanding of how the different Open ET and Tule and other ET tools you know about how they are used in the Napa Valley and to inform the model. But I was curious to know based on your expertise what you thought about what is being done to try to better constrain ET in Napa Valley and if you had any specific recommendations.

I am starting to pay attention to it more, but I have not. Thule was adopted pretty widely here in Napa early on as in, a lot of ag technology comes to Napa first because people can afford to to pay for it and try it out and test it and things. And so it caught on here, effectively with with a lot of growers. But in in terms of doing watershed stuff here, our my work was more towards the Central Valley for a long time in terms of conservation, but we are moving efforts back up in into this region for for things like exactly what we're talking about today to make sure that we're actually getting the measurements correct.

And then I just want to make sure I understand the two last slides that you showed. Is that correct to kind of understand based on this data and this analysis? The open ET does a better job than the surface renewal at being closer to the AD covariance at least for the area you looked at.

Yes.

Is that a fair conclusion from?

Yes.

Okay.

And we're we're preparing we're, because of all this discussion that's going on, we're preparing, what's called a buyer beware paper and I've told Vicky and some other people about this of just being very transparent about explaining energy balance residuals, where do these measurements come from, how does closure work, how do how do you do adjustments to that data and we're preparing a manuscript for that right now that we're gonna have out and happy to share that with you. But this is some of that data that will be in that paper.

Thank you.

So and all I will say all of them have uncertainty. So every one of those measurements will have uncertainty whether it's the gold standard, whether it's a weighing lysimeter. A weighing lysimeter is not perfect either because you're constraining the root system especially relative to how old vineyards are here and how much soil volume that they would be able to access. And grapevines in in Napa Valley for the most part are gonna be more stressed than they are in the Central Valley. And so the Wang Lysimeter system, while people say, well, you're measuring it more directly than any other way, it doesn't really represent the rest of the vineyard effectively.

So all have uncertainty but from what we're seeing with Open ET, in this region in particular, those models are working well relative to to the EDDI covariance. This is again over the hill because it's in Cloverdale and how that represents in Napa. There are site specific aspects of this that we would consider but the data that is most closely related to the conditions here, it does look like the ET, the open ET models are working well. And I will say that I the dyslexialexia one within that is the model that we have most worked with, but the data I represented on those last two slides is the ensemble, so the compilation of all of those.

I understand that you guys are looking at different areas in the state and different trellis systems. Has there been any work done on rootstocks as a variable would be one. Then I might have missed it, but in permanent crops, the difference between the ground cover options as far as a cover crop or cultivation.

We have done some estimates of cover crop water use with and without and how the model is doing to pick that up. That is what we're doing at the Oakville station right now is setting up new experiments for doing exactly that and also because of climate resilience aspects of that of of what comes in in terms of ground temperatures depending on what the cover is and how you're managing that. So thinking about the water system holistically. We have measured to your rootstock question, I'm a plant physiologist and work on rootstocks quite a bit when I first got here. We used surface renewal in Oakville on a plot that had one ten r and one zero one fourteen as comparison.

And we found differences in in terms of ET from that. There is not much work out there in terms of comparing root stocks across that sort of scale though.

Yeah. I I imagine the two Thompson's potted vines were on Freedom or something along those lines.

They were on

rooted actually. Yeah. So Yep. Yeah. Thanks. Sure.

You mentioned that the vines in Napa were more stressed than those in the Central Valley. Could you explain that?

I think the the growing strategy here, tending to have smaller vines and and wanting to use water stress to improve quality of the fruit is is what I meant by that. So atmospheric drought is a bigger thing down in the Central Valley of how hot and dry the atmosphere is and the vapor pressure deficit you would get from that, but they're using a lot more water. So at some of those sites down there, they're aiming for 40 tons an acre. So you could imagine the canopy size that's needed to to produce that versus, one to four here is typical. So it's a really different sort of growing system and why we've done stuff across that, the gradient for that exact reason. Okay. That's kind

of what I was thinking about.

Yeah. Thank you for that, for clarifying that. How

heavily is the model relying on actual CMS data given that you you show pictures that ours is not always maintained properly?

Not at all, Yeah. The the dyslexia, Alexia is not is not using the SEMAs data for that. I I don't know for the the modeling that's going on here of how much the the SEMAs ETO and other things. I can't speak to that. Great.

We use the the simmestation data to to bias correct our remotely sensed reference evapotranspiration in the model and our sense, that was in 2020. So looking back now, we're we're kinda reevaluating and looking towards using some better remote sensing options that that won't require that. So

Thank you. How big a project would it be to get the CIMIS stations in order and functioning properly? And is that, you know, so why is it, why do we have this problem? Seems like a lot's depending on that data.

Yeah, think about it since I'm being recorded. Yes. It is absolutely possible and this is something that once once we realized what was happening at that station, it it has been fixed. And you can see that from from the imagery, Google Earth imagery even shows that to you. Why is that throughout the state?

Yeah. I I think that's a DWR question in terms of maintaining those sites and and things like that. But I did hear from Vicky that there was some discussion about potentially having another type of sima station somewhere here in the valley as well too. So there's certainly interest and I think the the modeling from that still holds true and is is very useful especially for knowing essentially potential evapotranspiration of what could be happening relative to what your crop is doing. And having that as a relative measure is really useful for understanding sort of stress conditions and some of those But in many ways, if we have ETA now with the models and if we trust those models, then the question becomes is how much do we need those SIEM stations?

And so I think that's why there has been some reluctance in terms of maintenance of those things. But I would let DWR people speak to that a bit more.

Yeah. I guess that was where my head was at during a lot of this conversation of we've been looking at trying to work with DWR and and finding a new suitable site in Napa and getting site access and permission and agreements to site a new station if possible? And if this Oakville station is being reevaluated and brought up to speed and being maintained, is there a point in pursuing another SIMA station? And it sounds like you're saying check with DWR, but probably is useful.

Yeah. I would pull in some of the biometeorology people that I know into that conversation. I'm happy to to to do that with some of the folks that I work with in terms of what their perspective would be on that.

And just to clarify, all the SEMA stations are operated by DWR, owned and operated by DWR. Is it DWR program?

It is a DWR program. Yeah. And I don't know the owning and operating part. I think there is some partnership depending on where it's located. So some of those are located on grower fields and they have pushed to put them in and they put the money on the table to do it. I think they have people on staff that check on them regularly. It depends on how much those individuals use that information in different places. So I know of a grower in the Central Coast that actually put in his own so that that they had it on-site because they didn't trust one from five miles away. And it's still part of the DWR network and It's still in there and people can access that data. Okay. Yeah. So I think that part of it is still governed through DWR. Yep.

Yeah. I think my understanding is that there's some upfront cost to install and then maintenance would be the landowner. I I think we offered to do it for whatever site we're hoping to get sited in Napa. And I don't know what the maintenance is. They make it seem like it's as simple as wiping down a solar panel every now and again. I'm sure there's a manual that has a lot more to it.

It's Gotta get rid

of the

bird poop.

Yeah. The bird poop.

Yeah. Probably the size of

a quarter.

That is the same thing we're dealing with with our towers all the time too, right, is the birds of prey love how tall we put these things, and so they just come to that. So it's it's all sensor maintenance and having people to be able to be there. But our activity at Oakville is ramping up. And so if that is something that that we're interested in that data and if it's something that we know that this group needs, we can certainly be the ones that take that on to make sure that thing is is cleaner. And our vineyard managers now doing that.

Do we have any other comments or questions from the TAG before we go to public comment?

All

right. Thank you very much.

Thank you

very much. Doctor. Macron. Do we have any public comment in the room?

Online?

We have one caller. David, you will have three minutes.

Thank you. I just wanted to thank Doctor. McElroy for an excellent presentation. Oh, by the way, yeah, sorry. My name is David Graves.

I think there's more utility to be had with calibrating our remote sensing. And I think Doctor. McElroy used a word that's really important in the wider context of the general plan update, which is to say biometeorology could be incredibly important in terms of calibrating our Modflow one water Napa Valley integrated hydrologic model. That involves more sensing in the native vegetation than in in in addition to vineyards. But another aspect of what's happening at the basin that may be important is looking at these self supplied pumper component that was discussed on Tuesday versus the fee structure.

We don't really have a way of I mean, they represent, you know, 18% of the total, yet we don't have a way of tracking how realistic that number is. But I think remote sensing, even if it's of landscapes not the same as vineyards, could be incredibly important. And I also wanna put in a pitch for expanding the G tags to include expertise from doctor McElrohn's sector just because it's really useful, and it would be really great to have somebody inside our project being able to supply expertise. That's obviously not a call that either the GTAC can make nor I can make nor anybody with the supervisors, aka the Groundwater Sustainability Agency board can make. But I think having a more robust spread of expertise like remote sensing biometeorology is incredibly important.

It needs to be considered. So Jameson and and Brendan and I would put that on on your plate to think about and see how you could advocate for that. Thank you.

Thank you.

No other callers.

Great. Moving on to item five d, we have another presentation from Doctor. Andrew Fisher and Lisa Lurie at Santa Cruz. Are they here or is it going to be oh, great.

Hello. And I I believe you wanted to share your PowerPoint directly if I'm correct. Yes.

Let's see.

See if we have permission for you to do that.

Okay. How is that? Can you see my screen okay?

Yep, we can see it.

Looks great. Great. All right, well good afternoon everyone. My name is Lisa Lurie. I'm the executive director with the Resource Conservation District of Santa Cruz County and I'm here with my colleague Doctor.

Andy Fisher from UCSC. We're really happy to be here with you today and really grateful for the invitation. And we're really here to come and speak with you about a model program that we have developed in the Poppro Valley Southern Santa Cruz County called the Recharge Net Metering Program or REM, is an effective example of incentivizing groundwater recharge on private lands throughout our basin. So we're really here today to share a bit about our experience, kind of the why behind this program, the how, and to talk with you all about kind of where you might see potential for this sort of program within your broader thinking of groundwater sustainability and answer any questions you might have. Alright.

So just to orient us to the Pajaro Valley here in Southern Santa Cruz County and Northern Monterey County, this our our our water supply in the Pajaro Valley, like all all of Santa Cruz County is entirely locally derived, locally dependent. And so the Pajaro Valley groundwater basin has long been recognized as a critically overdrafted basin. And as such, the Pajaro Valley Water Management Agency, who's a key partner in this effort, their general manager Brian Lockwood was unable to be here today. But the PV Water was formed back in 1984 and established as a local entity charged with halting seawater intrusion in the Pajaro Valley. The agency was really derived by local stakeholders coming together to define the goals and the needs for the agency and has really set the stage for groundwater sustainability in our area.

The Poppro Valley is largely agricultural and focused on specialty crops. Crops. The agency serves over 70,000 acres with 30,000 of those acres irrigated agriculture. So again, to kind of paint the picture, we're farming strawberries, cane berries, row crop vegetables. The scale of water production, water use in the valley is about 55,000 acre feet per year and the overdraft is estimated at about 12,000 acre feet.

So with the establishment of Peabody Water back in 1984, that really kick started the planning, local planning for halting seawater intrusion and groundwater sustainability. First with the development of a basin management plan, which outlined key strategies and has since been evolved into our groundwater sustainability plan with PV Water serving as the groundwater sustainability agency. That plan itself, in terms of the key strategies, relies very much so on conservation. 40% of the target is meant to be achieved through water conservation. Our RCD partners really closely with PV Water in that program.

There's also a number of large infrastructure projects for augmenting and delivering supply. And then Recharge has emerged as in part as a result of really community driven efforts. In about 2010, some of the really key and influential landowners in the Pajaro Valley came together recognizing that that groundwater sustainability was both influenced by local land use and the solutions to achieving sustainability needed to be locally driven. They came together in a dialogue really trying to define solutions that the community could support and be behind. Within those solutions, conservation of course being one of them, groundwater recharge really rose to the top with landowners identifying, you know, could we find opportunities on private lands where the land is suitable for groundwater recharge, where we could put our skin in the game and be matched with support from different agencies to be a part of the solution.

This key group of landowners together with leadership from the Resource Conservation District and Andy Fisher and his lab from UCSC started kind of developing this idea of, well, what would it take to really support and incentivize recharge on private lands? And how can we ensure that those actions are achieving measurable and desirable benefits for the basin. And so from those conversations, this concept of recharge net metering formed. Essentially, how can we take the concept of net metering applied in renewable energy sectors and bring it to the problem of groundwater sustainability? So this program is very much a collaborative between landowners, between the RCD as a conservation practitioner partner, between UCSC and the university resources there.

And then key to it has been the support and leadership of our GSA PV Water. So how does it work? Essentially what we have proven in the Poppro Valley is a system of supporting distributed stormwater collection and infiltration systems. So we'll go into a bit more detail about each of the steps of this process. But essentially, we evaluate suitability for groundwater recharge across the landscape and then at individual sites.

Recharge systems are then designed and installed on selected properties. And key to this is having willing and voluntary landowners in partnership with their lessees, with their growers who are stepping forward and interested in participating. The water is then captured, infiltrated, and measured. And we have developed a third party certification team, which is partnership of UCSC and the RCD, who are charged with doing the monitoring and evaluating of that recharge. Key to the success of the program has been establishing trust in the system for that evaluation so that the outcomes from the monitoring is then directly applied to the calculation of rebates for landowners off their water bills.

So making sure that upfront we're all in agreement with how we're evaluating the effectiveness then lead to those rebates is really key. So how it works in terms of our partnership, there's a few key stages throughout this process that are fulfilled through the RCD and UCSC and I'll step through each of these. So first in terms of planning, we worked closely with UCSC to do a first a basin wide evaluation and then eventually expanded that to the entirety of Santa Cruz County and Northern Monterey County to look at anticipated suitability for lands for recharge. So this was looking at everything from hydrology, geologic conditions, soil suitability, and also modeling anticipated runoff levels across the basin. And Andy can speak to some of the details of this if y'all are interested in kind of digging into the details.

From that regional suitability assessment, then as we're conducting outreach and working with landowners who are interested in seeing if their site is a good fit for Renum. We then do site specific evaluations using a number of different technologies. And once we have alignment and kind of the threshold that we're looking at for projects to have a cost benefit sufficient for investment for project implementation. We're looking for projects that have anticipated at least 100 acre feet per year of recharge as the scale that we're going at. The RCD works with the project team and with the landowner to then secure resources for project planning, including design and permitting.

And so far, we've been securing funding for that phase through a number of public grant programs, and also landowners themselves have been contributing to that phase. Permitting for these projects can include a whole host of different permits from county permits, California Department of Fish and Wildlife, in some cases Army Corps, and Regional Board to name a few. Here's just an example of kind of designs that would be for one of our basins and Andy is going to talk about a few of the two of the current basins to show you a bit more detail there. Once we move through the planning and permitting phase, then we work with the landowners on construction and oversight of those projects. These are large capital improvement projects.

In some cases, there's pre existing conditions or basins that we can augment at a lower cost to increase their recharge potential. In other cases, we're starting from scratch in designing and then implementing basins. And the design generally is capturing runoff from a larger watershed area and then through a series of first sediment retention and then infiltration basins achieving benefits for the groundwater basin itself. Along the way there's a lot of work around adaptive management of these systems and then the long term maintenance to ensure that they continue to function into the future. For the monitoring and reporting aspect of Renum, this is really, really key and what's unique about Renum and the incentive program that we've developed is that it really is tied to measurable performance of these systems.

And so we're evaluating water that is entering and then infiltrating into the system each water year. Andy is going to show you some pictures of the ongoing monitoring that we have. And then the rebate that we've developed together with PV Water is essentially looking at the net infiltration of these basins, recognizing that there's some level of evapotranspiration that's taking place, and then rebating 50% of the pumping fee that that landowner would otherwise pay for an acre foot of water. So they're receiving that rebate off of their water bill. So part of the enabling conditions for this program are that PV Water has been monitoring wells in the Valley for decades now and has a pumping fee that they apply to growers throughout the basin.

Here's a summary of the three projects that we have implemented to date in the ReNEM program. The Boca Riza Ranch was our first project implemented and this was augmenting a pre existing basin there. The target for this system was 100 acre feet of recharge per year and we're seeing that. The Storrs Vineyard was another system that we really brought into the program. The program was created after the basin was developed And this was a bit of a strategic project to have a demonstration within a part of our basin.

But we recognized that it wasn't quite going to hit our 100 acre foot target but had good demonstration values there. And then the Kelly Thompson Ranch, we got online in water year 2020. This is a much bigger system and so it's been achieving about 160 acre feet per year on average. And then we have another basin which is in design currently and looking to go to implement next year. Overall, the goals of our program are to achieve about 1,000 acre feet of recharge per year through these systems on private lands.

And so we're marching towards that. The value of the Recharge Net Metering Program is a bit of a like an insurance policy for the agency kind of above and beyond the other projects that are in the basin management plan. And so, so far we've been able to really demonstrate that having these systems in place, particularly having them ready to go when we have big water years like 2023, they really pay off and can supplement the agency's goals towards groundwater sustainability. I'm going to hand it over to Andy to talk in a bit more detail about some of the projects we have implemented as well as the monitoring system.

Thanks, Lisa. I hope folks can hear me okay. This slide just makes the point that there's many scales of managed recharge. We've selected a particular scale that focuses on storm water from hill slope areas and working lands. And really, you can think of this as being part of this continuum from low impact development often set up close to the source of runoff to much more highly engineered and also more productive regional spreading grounds

that

can get tens of thousands or over 100,000 acre feet a year into the ground. We're kind of targeting this in between space in part because we felt like it was a big opportunity and it could be done with modest effort. And that's really been the rationale behind it. Next slide, please. This is Boca Riza Ranch.

We started monitoring there 2012, and the recharge net metering program wasn't even a gleam in the eye at that point. We were just trying to figure out how does this work, how much water goes in, how do we measure it, Why are the landowners doing it? How you know, is it worth trying to build more of these? We just really wanted to understand it. This is a working ranch, rotating crops, a lot of berries, but also vegetable and other crops.

And it's around 170 acres of drained area. This varies because it's a working landscape. And that's one of the challenges. When you look at a map, you can estimate the drainage area, but you need to really go out in the field and talk to people and see how the ditches are configured and so forth. On this land, the runoff is routed through a very small sedimentation basin and then into about four acres of infiltration.

And as Lisa noted, we're hoping through this work to get about 100 acre feet a year into the ground with this project alone on average. Next slide, please. And here it is in operation. These are all most of these photos are taken sort of during the rainy season. The one on the upper right, you can tell it's during COVID.

We're all being safe in the field with our masks, recovering instruments. But as rain occurs on the landscape, water is routed just with gravity. And the key here is is trying to control the inflows so you can measure them and then trying to collect enough data that could be augmented with Cynis and other data and and come up with an estimate of how much goes in the ground. One of the other key characteristics of the program is that we and the landowners and the water agency all sign an agreement whereby they agree to accept our numbers ahead of time. So we know there's always uncertainties in the flows, but we agree to do the best we can, and everyone else agrees not to quibble and just accept our numbers.

Next slide, please. Just last week, we put out some new instruments at one of the sites that are wireless, which is really nice because running wires across these systems is a challenge with wildlife. The coyotes particularly like to eat the tubing and the cables. And so we've worked a lot in the last few years to figure out how to armor and strengthen these systems. This actually shows a sediment basin for detention at another site.

And then we've actually got two different systems running side by side right now to test how well it works. And next slide, please. This shows the infiltration system, and we've got a couple of pressure gauges to measure water level. And then the wireless system, we have to put a riser on that so that the antenna will poke up above the water level when the basin is full, and we'll have that data. It's telemeter right now in real time.

We get the we're collecting data every twenty minutes, and we have it telemeter about every every hour. We're also we use these systems to test additional technology. So we've been using heat as a tracer to measure infiltration. And we found that when we put 10 or 12 probes in a basin and we average those results, they match really well with our mass balance. So that's another way to measure infiltration as well. Next slide, please. And we do a mass balance. It's in some ways like the presentation you just saw in ET. We measure all the things that are easy to measure or easier to measure or estimate, and then we solve for infiltration. That's really the crux of it.

So it does mean that the errors in the different methods accumulate in the infiltration term. But as I noted, we've also been measuring infiltration using heat as a tracer, and we get very similar numbers. This just shows an example, a fairly typical water year, water year 'nineteen, where we subtract for the program, we subtract what we consider to be incidental infiltration that would have occurred anyway if the project weren't here, and then we report the net infiltration, and that forms the basis for the agency issuing the debate. Next slide, please. And now that we've been here long enough, it's pretty interesting to see what's going on.

This plot shows precipitation on the x axis versus the amount of runoff that was collected on the y. We have two different sets of units for SI units and for more traditional English units. You'll note there's a lot of variability year by year. And also, even in the same year, one amount of precipitation that you get that year can be quite different from the amount you get in another year. And in fact, there's kind of two trends here.

Lisa, if you'll advance this, you'll see two arrows coming up. There's kind of a lower level trend and then a much higher level trend. So, again, the same amount of rain, but a lot more runoff. And this has a lot to do with persistence, how closely spaced are intensity, how strong are the storms. And one key impact of climate change, over the last hundred and twenty years, we did the analysis for the region, and the mean annual rainfall hasn't changed much at all, but what's changed is the intensity.

More rain is falling during a smaller number of big events. And this is going up in the data, and it's also predicted by the models. So it's another thing to think about as you think about the future. Even if the rainfall stays the same, if more rain falls in an intense way, you're going to get more runoff unless you can hold some of that water back on the landscape and allow it to infiltrate into the ground. Next slide, please. This is that new site that Lisa mentioned. It's called Kelly Thompson Ranch. And this was really exciting because they called us. They called us on the phone and said, you know, we'd really like to do something. Will you come out and talk to us?

And we did, and we looked at their property, and this drains a much larger area. You've got rangeland in blue on the left and then cropland in in the black. And they had a parcel that wasn't producing a lot of of of crop. But when we did some studies and realized that that was a paleo channel, an an area that used to be a tributary to the Pajaro River, and therefore, were buried sediments that could receive water if we could open up the ground, if we could remove that finer topsoil. So we developed a project here and really took this from scratch.

It was a pretty exciting process. Next slide, please. This was the design. And in addition to designing the system, collaborating with the landowners and the engineers and others, of course, the permitting agencies, We also did an experiment here by adding carbon rich materials to the soil in an effort to improve water quality on the way in. That's something I'm happy to talk about a little bit more later if you have questions. Next slide, please. And here it is when it was just finished construction and the carbon amendments were being added. And then we put out our instruments and waited for the rain. Next slide, please. And that first year was a pretty good year.

The basin filled multiple times and it infiltrated pretty effectively. And we now have four years five years of data. I've got another year's worth that need to be processed here, but hopefully soon. Next slide, please. This shows the five years of data we have. 2023 was, of course, quite a wet year. We got around three fifty acre feet with one site. The basin is about the same size as at Boca Riza, but it just drains a larger area. It's interesting, though, at lower rainfall, it gets less runoff. And that's because it's such a large drainage area, it really has to wet up before you get significant runoff that is collected.

And this is water that returns to the Pajaro River ultimately. But during these big years, it's flowing into the river when that channel is full or even at flood. So the water we're putting in the ground here is not the last drops of water that are needed or the river or even for this paleo channel that's not even a channel anymore. This is excess water that would otherwise flow into the river and out into the bay when it doesn't provide much of an environmental benefit. Next slide, please. And on this, I'm going to pass back to Lisa.

Yeah, great. Switching then to thinking about the cost effectiveness of this program and kind of how to make the case for an incentive. We've been working with researchers up at UC Berkeley to do a cost benefit analysis of the Recharge Net Metering Program and then also with partners at The Nature Conservancy to be kind of looking forward to the future growth of the program and how that influences cost effectiveness. But essentially, what the numbers show in terms of the projects implemented to date and then the projects that we anticipate implementing in the near future is that the cost per unit of acre of water, the cost per acre foot of water recharge to the basin is significantly less than the next alternatives in the basin management plan, in the groundwater sustainability plan. And so for the agency, this is a very attractive element to add and to have included in their overall approach.

You know, the other infrastructural projects are essential for consistent water supply, but augmenting the program through supporting recharge net metering creates, you know, a very low cost per acre foot additional resource for the basin. So at its core, really what the program comes down to is having a really strong partnership between local landowners, between the Groundwater Sustainability Agency, in our case, Pauver Valley Water Management Agency, and the third party certifying and implementing partners. In our case, that's the Resource Conservation District in UC Santa Cruz. And at its core, essentially we're connecting solutions in terms of groundwater recharge projects to incentives that can be locally driven and then supported through also state and financial resources to achieve the desired results of groundwater recharge and sustainability. But these elements are adaptable, right, in terms of who is playing these roles, in terms of the types of projects that are supported, and in terms of the types of incentives that could be driving recharge.

So we're looking ahead to the future and what that expansion and adaptation of this program could look like. As Andy mentioned, the systems we've implemented to date have focused on this model of distributed stormwater collection through a series of recharged basins. But there's all sorts of different practices that could be supported and incentivized. From flood MAR, looking at recharge potential, augmenting it within levy setbacks, looking to incentivize recharge within built environments, and then other more cultural practices that can be incorporated into agricultural production like cover cropping and rotational cover cropping to be further augmenting the infiltration and recharge benefit across the landscape. So just to summarize, what we have the problems that we've been looking to solve in the Pajaro Valley through this program that are, you know, fairly universal across different basins is really looking at how can we be supporting and promoting and bringing to scale actions across the landscape that really engage the communities in proactive and a collaborative partnership way that really can look at better evaluating the suitability of our lands for recharge and focusing our efforts and our investments there through regional and site specific evaluations.

We've been able to move from a lot of unknowns around what are the costs of these projects and relative to their benefits to having real clear documentation of those costs and benefits, and then really working to develop a program that can tailored and adaptive to local conditions and needs. So in terms of where we're heading, we are working now to bring this program to scale within the Pajaro Valley. It has moved from a pilot project, pilot program within the PV water Agency to a sustained program. And ultimately, again, working towards this 1,000 acre foot goal, which we anticipate being from probably 10 projects. But we're also now looking to support adaptation of this program in other basins.

We've received a lot of interest, lot of calls like the call we received from Vicki from other basins who are interested in learning more and really thinking about how might this be relevant and adapted to their particular basin's needs. So we're really happy to be focusing time on reaching out to other basins, providing information, and really having this type of discussion in hopes that this model can be adapted and benefit groundwater sustainability more globally across the state. This is just a timeline where we are now in the program, but I think really the take home is we're here as a partner and as a thought partner really to you all and to other basins going forward and evaluating the applicability of this program. And then we're also working to build resources and do fundraising to help with that seed funding and support for other basins as well. So that's an area that we'd be happy to follow-up with you all on if this is something that's of interest to you.

I think with that we will wrap it up just with a quick summary slide here of the program and the benefits that we've seen in the Pajaro Valley. And I think really for me what it comes down to is that this is a program that really has been reliant on strong community participation and leadership. And so really key in that is having those champions within the community who are interested in supporting its advancement. I think with that, we will open it up for questions.

Thank you. Definitely a major topic of interest. I had a few questions. The first is related to the site suitability work that you guys do. And I think it was like slide six. It shows the surface factors. It's kind of a major part of the work that you guys do. Can you talk more about what that looked like for the basin that you guys did the work in and if there were any more intrusive studies that were needed to be done?

Shall I shall I take that one?

Sure. Great.

So we started a project about ten years ago, with funding from the State Coastal Conservancy. It was part of a climate adaptation grant, and it was to gather a bunch of data coverages and do a whole bunch of data massaging and merging in order to create a series of maps like this. And I'll just note for the Pajaro Valley, we have a new version of this map, which is part of a study that links in runoff generation so that we can look at the suitability, but also look at how much runoff potential there is. And with any luck, that's going to get submitted tomorrow. And as soon as it's submitted and in review, I'm happy to share a preprint that talks more about the methods in detail.

But briefly, we went out to both public, federal, state and all sources in order to acquire data like soil maps, regional geologic bedrock maps, take a digital elevation model that's publicly available and then do some corrections on it, remove artifacts and smooth it out. So we collect different kinds of data for the subsurface. Part of what was a little bit unique about this work is many MAR suitability studies don't include the subsurface. So for example, the SAGD index, the so called groundwater banking index, is really based on soils and land use. And one of the big issues, though, is whether there's space and a pathway into appropriate subsurface storage.

So the way we handled that in this case was we adapted data sets that had been developed for a regional groundwater model. And this was really helpful because that provided us with architecture, properties, you know, the thicknesses of different layers, the presence or absence of clays and so forth. And in one of the early studies about ten years ago, we took the results of suitability and then we could add hypothetical recharge projects and rerun the regional model to see what effect they might have over time. So by integrating the work that had already been done with modeling along with a bunch of data coverages, I think we were able to leverage just a lot of earlier work, you know, really more than a decade of earlier work that had already been done. There's a whole literature on this kind of approach.

It's called multi criteria decision analysis. And there's hundreds of MCDA papers on charge suitability. Different folks use different data sets. A lot of it just depends on what you have access to. But a lot of the work really goes into finding the data, getting it registered, checking the provenance, fixing errors and artifacts. And then once everything is reconciled, actually merging the data sets into GIS isn't too much work.

Thank you for elaborating on that. I'll ask one more question and give everyone else a chance. Just curious about any any work that was done or is being done with the state regarding, the capturing of the surface water that is put into these reservoirs or basins, what that looks like?

Sorry, I'm not I'm not quite sure what you're asking. Are are you wondering if the state is involved in the projects or?

I guess I understood that the the basins are filled with surface water capture. Is that correct?

They're they're they're filled with storm water collected storm water.

Got it. Is the

We're partnering with with state agencies. We have right now, these projects are being supported by Department of Water Resources and Department of Conservation through the multi benefit land repurposing program and through the IRWM program are two of the programs currently supporting the work. And then we've also had support from the California Coastal Conservancy in project design and implementation as well.

Thank you. Other questions, comments?

If I could follow-up on Albert's first question about the site selection. So the two examples that we or two of the examples we saw, Boca Riza and Kelly Thompson. So those were both places where you had runoff from foothills coming down across presumably alluvial fans and then into this lower area where you could capture it and infiltrate. And in the case of the Kelly Thompson, you had this wonderful paleo channel that you could use with coarser sediments. How common do you think that pattern would be across the landscape?

Is this what we should be looking for to get all the elements to line up for a successful project?

Yeah. Is it okay if I take this one, Lisa?

Yeah, yeah. And I was thinking to kind of go from the it's the regional suitability then to the site specific suitability.

That's right.

And it is a bit of getting all the stars to align for sure.

Yeah, it really is. And I'll also just say that this has been part of our challenge is these opportunities sometimes come up for so called shovel ready projects. But a lot of time, what we need is to look at five properties or eight properties to find the one where we get the right combination. The other thing is that although we're definitely moving more towards a mode of being deductive in collecting the data and then finding sites and then looking, In fact, as the program began, we kind of did it backwards, which was we looked for people who were interested and then we looked at their properties. Because at the end of the day, we need partners who are excited about doing this in order for projects to really be possible.

Yes, in fact, both of the sites, Boca Riza as well, there had been a preexisting basin. It wasn't fully engineered the way it is now. And it had been set up because an earlier grower had wanted to avoid having runoff go on to a neighbor's property. So they had set up this basin in naturally occurring swale or a quasi naturally occurring swale. Well, that's also a paleo channel. So in fact, they both are. And the first one at Boca Risa works even better. It's really interesting. It's about five to seven feet higher on the edge of the valley. So it's at a slightly higher elevation.

It's also a bit farther from the river. And those channel sediments, we've now investigated with electrical tools and with this direct push rig. And the buried paleo channel is about 10 feet thicker below Boca Risa as well. So you're absolutely right. The key in our mind, because we're trying to use a small area of land to generate a relatively large benefit, it's super important to find the right spots.

Now, my colleague Graham Fogg, you know, kind of like to say flood it all and let nature sort it out. You know, if you have enough water and you have enough land, might not need to be quite as picky. And I think that's sort of true at the limit. But I do think particularly early on, it's important to find the places that look like they're going to work the best. Because everybody's putting in effort, and the landowners have skin in the game as well.

And especially if these are working lands and they're productive, really don't want to be taking prime farmland out of production if we can avoid it. We're trying to find the right locations where not only do the conditions align, but it's consistent with what the landowners want. By the way, another kind of landowner that we're working with now are land trusts. And in some cases, they'll acquire property, and they may want to farm part of it, but they might want to do other activities on another part. An ecosystem restoration, enhancing groundwater recharge ultimately is a restoration of system services that have been lost over time because of development and shifts in the climate.

So if you imagine these landscapes a hundred years ago or two hundred years ago, there was a lot more water soaking into the ground. We have changed that. So part of the the goal of these projects is to restore a fraction of that hydrologic system service, and that could be done with a small area with really good conditions. It could also be done with a larger area with moderate conditions where you're also going to get, for example, habitat benefits or improvements to water quality because we're increasing the retention time and we're reducing the export of, say, sediment and nutrients. But at the end of the day, it's like you said, you need to find places that are the right places.

We don't want to go out and just throw projects willy nilly across the landscape because it's going to use a lot of energy and effort, and we're not going to be able to generate as much benefit or be able to document. That's been important as well is really measuring the improvement.

No, no. Yeah. I think to that point, we've found that just the importance of investing the time and the resources in doing the site suitability assessment is really critical because you can often find that what might look like a really great site from the regional assessment once you get into the details of it is not or vice versa. So just factoring that into the process.

It's very exciting. I'm wondering in terms of being able to make an assessment over a larger area and identify potentially suitable sites, I imagine you could use geophysics and topography to identify some paleo channels and if you were to be able to do that on a large scale and at least have an initial set of potential sites that you could then zoom in on, find out if the landowners might be willing and you could do further tests?

That's right in general, I would say. However, we have aerial surveys over this, and and none of them detect these channels. They're too small. The footprint of these paleochannels is below the resolution of the aerial electromagnetic data. Now in the Central Valley, there's been a lot of interest in finding these incised valley fill deposits. Those are in general, like quite large. I'd say even within those, you need to find the right spot. So even if you're even if you do find a really big feature, you're going to need to go to the farm and do the local work. The other really good information is from the growers. They know what parts of their property infiltrate quickly.

So, you know, it's a little bit of detective work. I think the geophysics is helpful. I think the soil maps are helpful. But as just two other examples, we're working at a site now. We have this project Lisa mentioned. When we first went out there, we were pretty excited because the topsoils are incredibly sandy, coarse grained, well sorted. These are dune sands that probably migrated up over terraces millennia ago. However, when you get about 10 feet down, you hit terrace deposits. So when you look at the surface soil, it looks wonderful. But it turned out we had to be very careful where we picked the project site to find buried deposits that are at a very small scale, you know, a couple of acres that have the right properties.

And then at Kelly Thompson, it was the opposite. The surface looked terrible, but the paleo channel was below them. So I think the regional geophysical data is great, but if you just rely on that, I think you're going to miss a lot and potentially be misled as well in some places.

Thanks.

Can you talk a bit about between where you are now with those three sites and aiming for 10 plus sites, where do you see the main challenges? Is it on finding sites, finding willing landowners, securing funding, all of the above?

Yeah, great question. So a few challenges that we're actively overcoming to move forward. One has been really working to shift our approach from more of the opportunistic project by project, seeking of resources, to really creating and resourcing a programmatic approach. So we work to develop a sustainable business plan, develop to scout out our staffing capacity needs, and to start bringing in resources for that. So really looking to increase our dedicated staffing as kind of a step one.

And then really a lot of the kind of getting us to the next suite of projects is increasing targeted outreach to landowners and growers throughout the basin and particularly in areas that seem well suited and then dedicating resources for the suitability analysis to identify and move the next suite of projects forward. Once we have projects identified, the process for seeking and securing funding for implementation is pretty straightforward. There's a lot of interest in supporting the shovel ready projects, but it's getting to that shovel readiness and getting through the work of site assessment and planning, that's really critical. So for us, seeking that programmatic support for that work has been a really high priority. And we have traction in that and success there.

So feeling optimistic at our ability to take this and continue growing it. Another piece in our next phase is really working with the agency and looking at, you know, we've gone from a pilot phase to demonstrating success. And where do we go from here in terms of our continued partnership and our ability to leverage resources and really extend the support for the additional project implementation. And then something we're hearing from growers and from the landowners who have participated so far is the incentive is great for bringing people to the table and for those who have, as Andy mentioned, like sites that are already under producing or they're looking for, you know, they're coming in with a strong interest in supporting the sustainability of the basin. But where can we look to grow those incentives to get to that kind of next tier of landowners or growers for whom it might be a bigger opportunity cost for them to participate?

So those are some of the questions we're looking to answer.

I also had a question about the maintenance of those infiltration basins. It's a big deal to ensure that they will continue working overtime. Who is responsible for maintaining the basin? Is that the landowner or is that something that the RCD is helping with?

Yeah. So the RCD and Andy provide advice and guidance, but the responsibility for the maintenance activities is part of the agreement with the landowner. And in fact, that's how the rebate was established and kind of scoped, was to make the rebate sufficient enough that it would offset those operations and maintenance costs. And Andy, you want to speak some more to the nature of the maintenance?

Yes. Usually, it's a matter of scraping away some debris. Many of the inlets have screens or barriers that help to hold back, you know, sticks and random trash and so forth that might collect. And then the basins themselves, once they dry out, they need the the top layer of accumulated sediment needs to be scraped away. And we ask the landowners to disc after they scrape.

And every couple of years, we suggest they do a deep rip with like a three foot tool to really open up the soil and restore its infiltration capacity. And it's interesting. One year in one of the basins, the grower did not do that, and the water came in the next year and immediately perched on top of the sediment from the previous year. Like we have a beautiful test of nonperformance. And then the next year, they scraped and they disced and they ripped and disced and everything came right back.

So part of the way the program is set up, because the rebate is directly tied to performance, that gives an incentive for the landowners to maintain the systems. Also, because these are growers, they know how to do it. They're very efficient. They have the staff and the equipment, and they can do it at a relatively low cost. If you had the agency do it, for example, it would be a much more complicated and expensive process.

But growers are able to move earth and scrape and spread that around and so forth just as part of their incidental operations. And as Lisa said, this was what sparked the whole program to begin with, was we looked at that first sight and just thought, why would people take this on if they're going to have a cost every year to maintain it? And while there may be a long term benefit, you know, that's pretty off in the distance. And can we just make them whole for the costs that they take on when they do the maintenance? And that was really the motivation behind the rebate, Bridget.

Great. And I have another question on kind of when you are looking at sites, are you also evaluating the fate of the recharge water as part of evaluating the site in terms of how close you are from the river, for example, and maybe some of the recharge water may not really replenish the basin. I'm wondering if that's also taken into account.

Well, it's a good question. We've written proposals to do tracer studies that have not been funded. You know, the key here is we try to get the water in below the level of the river. We try to get the water in in places where water levels have been drawn down in the basin. Actually proving the fate of that water is quite challenging.

In a lot of tracer studies, people monitor many, many wells and never see any tracer at all. The details of the pathways are difficult to determine. But, you know, I think the key is to find the right locations where that is the most obvious place where the water is going to go. If you if you try to do this like in a river channel channel or right next to the channel, I think you'd have a problem. So a lot of natural recharge occurs around basin edges, and that's also the logical place to put these projects because that's where you collect a lot of runoff from the foothills.

And I think you just have to look at the site and use sort of hydrologic principles to decide where the right places are. One could attempt fingerprint that water or, you know, trace the water, but that's a really it's done academically, but those are expensive studies and they're quite hard to repeat. So I'd say, you know, if that becomes an issue, it can be done. But to sort of make it a boundary step that you have to get past in order to implement this, I think, would really be prohibitive. I don't think it's strictly necessary in many places.

Great. Thanks.

If I could follow-up on the previous question about the maintenance. What you described reminds me very much of what LA County does in their debris basins with their spreading grounds. Is that a fair analogy?

I believe it is. I can't claim to know in detail what they do, but when I go to recharge meetings or talk to other practitioners, what we do sound is quite similar to what others do. But it obviously varies with the specifics of what they're dealing with. But, yes, in general, this is always required in any recharging system. Yeah. Just about, you know, other than direct injection of of potable water or something like that, you're always gonna have to deal with and to some degree sediment. It might not be sediment that flowed in, but it could be sediment that's resuspended and then deposited again.

Yeah, and of course that has implications for the potential for multiple use of these sites is that you can't really have even a football field or something there because you've got a disc it after each big year and deposits, right? It's pretty much you're pretty much restricted to the one use.

Well, that's how we've done it. As Lisa noted, you know, I think there's a lot of potential to adapt this to other conditions. If there were an appropriate multiuse area, that would be a conversation worth having.

Okay. Thanks.

I had a quick question on you mentioned cost to the landowner. And I'm just curious, since some of it is grant funded, how much are these properties that are being asked to put up for installing and maintaining these?

Well, currently we are securing grant funding for the bulk of the project design, permitting, We have had landowners contribute to some of the design costs providing a match. But that is the bulk that we're funding through the state or federal funding. What the landowners are primarily contributing at this point is the operations and maintenance, which is offset through the rebate. And then really, it's the value of the land itself that they are contributing to the systems. And so in some cases, that is land that was already out of production or planned to be taken out of production.

But that's where, as we're looking to scale up and continue implementing more projects, we anticipate that there's more and more costs to the landowner that are more the cost of the land and the opportunity costs of foregoing production if they're setting aside land that is currently farmed.

Thank you.

Hi, Lisa. I have one question for you. These rebates on pumping fees sound, I'm sure that would be super enticing to our growers because our Growers Sustainability Agency just passed a resolution two days ago to enact fees starting in a year from now. So I was curious, what are your pumping fees there?

Yeah, the pumping fees are, I can pull up the exact numbers, it's about $350 per acre. We have a delivered water zone where growers receive recycled and treated water. So the fees are a bit higher there. But throughout the rest of the basin, it's about $350 And right now, the rebate is set at 50% of that cost per acre foot.

That's interesting because that's just a little back of the envelope. And for a typical parcel in the Napa Valley Sub basin, which is nine acres, and assuming an application rate of like 0.3 acre feet per acre, which is kind of on the low side, that would make the if it was your rates, it would be $945 According to the rates our GSA just passed, that would be about $900 So I just wanted to put that out there for comparison. Any time we're talking about numbers and money, people want to know, are we more or less? So thank you for that info.

And I'll say those and this is a good question for PV water. Those rates are set, I think, every five years, and they escalate. So we're coming up at the towards the end of the current rate cycle. And right now, they're starting the process of the next rate setting.

Thank you.

So as one example, for 100 acre feet per year, which is kind of our threshold, you know, to kind of justify the effort, we're hoping to get 100 acre feet per project per year. And given the recent cost of water, it's around $15,000 that the participant would receive. So it's significant, and they like getting that rebate. Of course, it's not as high when it's dry, and it might be higher when it's wet. But that's about what the 100 acre foot per year target or threshold would get.

And by the way, the other key point there is the agency is issuing the rebate and at least some of that water that's going into the ground can be served again. So unlike energy net metering, which costs the electrical utilities money and freaks them out, recharge net metering as it's being applied in the Pajaro Valley can be revenue positive for the agency.

Thank

you.

We will now move to public comment. Do we have any in the room?

Chris Malin, executive director of iCare. As soon as SGMA passed, these projects started coming up for recharge. But the disenfranchised communities really came forward with big concerns because, there's people who get their drinking water from the ground. And, there's a big question about ag runoff percolating into the groundwater and polluting the groundwater. The studies show that it takes about ten years for those pollutants like nitrates to get to the groundwater, but once they get there, they permanently pollute it.

You can never recover it. You can never recover the water quality of an aquifer that's been polluted from ag runoff storage that percolates down into the ground. And this versus other types of recharge projects where it is not ag runoff. So under the ground, you don't have the benthic macroinvertebrates, you don't have the plants to filter the water. It's a closed system without the immense biosphere that is on the surface that helps filter freshwaters that flow through the landscape.

So this comes with great risk, and I noticed the water board is not a partner on this. So I'm wondering about the permitting. I'm wondering if, you're doing baseline data monitoring of the groundwater, and your projects, to see if there's pollution occurring, which it will eventually occur, but it takes a while. And, I would just ask that, you also present that information to the TAG in Napa County because I know there's a lot of research going on at the state level, at the water, resources control board level. There are scientists studying this in the state of California because it is a concern.

And I would like to see you, you know, talk about this and what you know about it and how you're looking out for the public trust so that our groundwater doesn't get polluted On a person's property, they're percolating it into the ground. But when it gets down there, it gets into the aquifer. So it's everybody's water. And we don't want these projects that could pollute our drinking water in a you know, being threatened by a pollution plume under the ground because it seeps and flows under the ground. So I would like to see that addressed.

Thank you.

Opportunity to provide some information?

Yeah, if it's okay, we just didn't show that today. We're actually doing quite a bit of work on that, but in the interest of time, we just didn't get into that. We have shown year after year with our annual reports and with peer reviewed research, the water we're adding is better than the ambient groundwater in terms of water quality. And by adding bioavailable carbon in the form of wood chips and other materials to the base of the basins, we can get the water even better in quality on its way in. So you're absolutely right.

It's a concern, and that's one of the factors we look at when we look at the sites. So any place that's generating highly contaminated runoff would not be suitable for a project of this kind, without a doubt. So anyway, we can follow-up, and I'm happy to send papers if you want to see the research that we've been doing as part of this program.

Yeah, I really appreciate the comments and share those concerns. Like Andy said, that's absolutely part of the decision making around site suitability and making sure that the quality of water that would be collected is better than the ambient groundwater quality. And also to add, the Regional Board through the three nineteen program supported Andy showed in one of the pictures the various trials that we've done in the Kelly Thompson Basin, putting different substrate in the basin. That was funded in part through the Regional Water Board and enabled us to really look at monitoring water quality going in and infiltrating through the different medium for nutrient and pesticide reduction through those various treatments. So points are really well taken and absolutely part of the consideration.

Thank you. Any other comments in the room before we check online? Online?

David, you will have three minutes.

Thank you very much. David Graves again. I, I've had an email exchange with doctor Fisher, and I as a a slug alumnus of UC Santa Cruz, I'm I'm very proud of the work that is being done by the hydrology unit, and this is this has been as the previous one was, this is a great presentation, and I think speaks volumes about the ways in which our technical advisory group could be enhanced by additional areas of expertise. Again, not my call and not the tag itself's call, but I just wanna thank Vicky for apparently, Vicky Kressinger is the source of bringing the group here today. Couple of things about the I had a question about how big is the area of the Pajaro Valley Water Management Agency, but I also wanted to say that its groundwater plan was adopted as an alternative plan because as noted early in the presentation that the authority started, I believe, 1984, and it's one of only, think, well, less than 10 fewer than 10 basins that had a plan that was adopted as an alternative plan because the work has been done thank you for that.

The the work has been done for a long time. There's a serious threat, for example, of seawater intrusion, which gets everybody's attention in a high value agriculture zone like Pajaro Valley. So there's a lot of, for example, recycled water use, as was mentioned earlier by miss Laurie. One question I had was the extent to which it's been appropriate to look at the impact of these infiltration efforts on groundwater dependent ecosystems and surface water groundwater interaction. Thank you.

In response to the first question, I just put up here the intro slide for PV water. So the PV water region, it's about a 70,000 acre valley.

And you're correct that PV Water had been doing basin management planning for decades. And coincidentally, they were sort of at the last stages of an update right when Sigma was becoming a law. And so they were able to repurpose their existing planning documents as a BMP alternative. That's correct. And it didn't come easily.

I'll say they've been through a lot. You know, they've really struggled with gaining consensus and coming up with a long term plan. But they ended up, because of all that work, being being in a good place once Sigma came about. It's interesting, though, in their plan, they're not required to consider much about GDEs because water levels were already below levels in many parts of the basin that supported base flow. And so in other words, because sigma doesn't require restoration, it only requires that you stop the imbalance, Essentially, because that connection had already been broken, it's not really part of their plan.

That said, if they're ever able to bring water levels back up, they will ultimately reconnect with some of those systems. The other point is that it's a layered aquifer system there. The one they primarily draw from is somewhat deeper. And the shallow alluvial system, you know, that does contribute to water that's added there will work its way through the shallow layers over time. So, you know, there are ecosystem benefits, I think, that are generated by projects like this.

Because the amount we're adding per project is modest, it's hard to see it in the whole basin. You know, the whole overdraft is as shown here around 12,000 acre feet. At the build out, we're hoping to bring the program to a thousand. And I think at that point, then over time, you may see some of that benefit, like raising water levels and reconnecting streams.

Thank you.

We're actually in the middle of another study along the Pajaro River looking at that surface water groundwater interaction and the effects of, including the effects of drawdown of the regional groundwater. But we're we're a couple years away from having that ready.

Great. Thank you very much. We're running up against time here.

We have one more caller.

One more caller. Thank you.

Brian, you will have three minutes.

And just a reminder that the the public comment is just that, just a comment. We don't necessarily need full responses to all the comments. Thank you.

Hi. Yeah. Brian Ron. Excuse me. Soil scientist in Anglin. In your previous slide, it showed some resistivity data. It looked like you have an instrument that was going across the soil surface. We used resistivity data to soil map quite a bit, and some of the resistivity instruments are very good at identifying texture and skeletal soils, rocky things. And I'm interested in the instruments that you use as opposed to and the depth at which you're looking. And that slide, it's hard to tell.

Section? Do you know if that's a cross section or that's or or is that looking at the surface of the soil? Correct. That's it. That's all.

Thank you. And, yeah, feel free to respond as appropriate, but we are running up against time.

Andy, you want to give a

quick response? Yeah. Ran a bunch of T TEMP surveys the last two years, and we're struggling with the interpretation because although it's commonly interpreted based on texture, there's actually five or six factors that impact resistivity, including saturation, which is highly variable in layers, can go saturated, unsaturated, saturated, unsaturated, and it plays havoc with the electrical data. So we're we're working on that right now. It it does help, but it's not a panacea.

You cannot turn the electrical data directly into lithology with confidence in this area. It's just there's too many factors that are kind of overlapping. We're hoping to develop a good path for that to help with that.

And this is a cross section visual here.

Thank you. Do we have any other comment, Linda?

No other callers.

Great. I want to make sure we have plenty of time for our last presentation. Worked through the break a little bit, so maybe we can reduce it to a five minute break and stretch for a minute. Do you guys feel like you have enough time? Yeah.

03:50.

Thank you.

Thank you, Lisa. Thank you, Andy. Thank you very

Alright. Welcome back, everyone. Duncan McEwen with ERA and Nick Newcomb with LSCE are ready to give us a presentation on GPR implementation and managed aquifer recharge.

Awesome. Off we go. Thank you, Chair Philip Eliot and members of the TAG, Duncan McHugh with ERA. So we are going to cover updates on GPR implementation. So just a quick recap, the water conservation work plan and groundwater pumping reduction work plan, the GPR, are those couple of management actions in the GSP.

I'm going talk a little bit about the extended replant and vineyard removals concept that we've talked about previously, and then we'll show you some numbers on what's, you know, some estimates on what's come out and just touch briefly on market conditions. And then we're going to spend most of the time talking about items three, four, five. So project one in the GSP is managed aquifer recharge. We've had this item to look at what we were calling like a recharge feasibility study. We use that term still.

I think it's a little premature because there's not like a project. It's more like kind of an investigation into recharge opportunities. So we'll talk about that recharge investigation or recharge feasibility study work. Nick's gonna talk through some of the work on modeling and water rights. We've been in touch with folks and had some good meetings, you know, some of the real practical issues with with implementing recharge.

And I'll talk through some of the scenarios that we're looking at for how this could work, which we've talked about at previous at previous tag meetings. So that's the game plan. This shouldn't be new. You've seen this. I mean, just everything with GPR, these are kind of the five guiding principles that that we've been using, I think, pretty successfully for the last year and a half or so, whatever it's been that we've been working on implementation steps.

And then here in graphical form is what I was just describing to you verbally. So you've got kind of input from different folks starting in the leftmost column, the management actions one and two, the water conservation work plan and GPR work plan. We're going to talk through today that light blue column three, some work that we're getting going on aquifer recharge. And then we've talked about expanding recycled water use. I mean, that feature is in a couple of the the work plans.

And obviously, these things are all, you know, interrelated. There's a bunch of different elements that we're working on, and we'll continue to bring updates to you all and get feedback as we're as we're working on those. Alright. So this extended vineyard replant program concept, which we've we've talked about, I think we brought it, sometime earlier this year to you all. But the idea would be that if you've got minions that are coming out, can you offer some type of incentive to keep them out a little bit longer?

And then the follow-up question is like, well, is there other opportunities for that ground where you could also increase recharge, you know, increase infiltration into the groundwater? And we'll talk through some examples for how this could relate to the recharge scenarios that we're looking at. In fact, we've got a a whole recharge scenario that is exactly that that's exactly that concept. And then, you know, the big considerations are obviously where that would occur. So Nick will talk about water groundwater modeling that will be done, you know, is not done, but will be done because, you want to get best bang for your buck and benefits for the groundwater system.

And then I'll talk a little bit here about market conditions and what's been driving some land idling that's already out. So I've shown this picture before, just, you know, kind of we've got GIS data for the the sub basin and the field level, and you've got points of diversion. So you can start to kinda and I'll show you some examples for scenarios for recharge or extending vineyard replanting, you know, the age of the vineyards, you know, where these are located, can start to think about, like conceptually, not picking specific fields or anything, but just conceptually within the basin, you know, where are there opportunities for these types of programs. So that's what we're working on right now. So vineyard removals.

This year, we've put together an estimate to look at how much land is out just through the 2025 year. So that's not including land that was removed previously, like in '23 or '24 and is still sitting idle. So it's kind of a conservative low estimate looking across the valley. You know, you you all know as well as we do. I mean, we went back, looked through the data, just looked at, you know, looked at where prices are in real terms for major grape varieties up here, where input costs are in real terms.

I mean, the short answer is costs are up, prices are down, margins are down, and it's tough conditions for the has been tough conditions for the the grape industry across the state. So, you know, what what are the opportunities? You know, what are the options to adjust to that? Well, you know, maintaining current operations, replanning potentially on a shorter time line. Right?

So this gets to this idea of are there ways to incentivize that, keep land out a little bit longer. Switching crops, not a big thing in this basin or this valley, but across the state and other areas that's happened. Grape Growers has put out a number of things about mothballing vineyards, just kind of keeping them on minimum maintenance just to kind of limp along through poor market conditions and then obviously exiting the industry. So we were interested to know how much land has come out and where across the valley. We've looked through a few different data sources.

I mean, the simplest thing is just Google Earth images looking at where land is, and you can see, you know, all the trawlasing system piled up and when stuff comes out. But then also looking at ET data with Open ET, the assessor data, and what their replants are, and then put that together to come up with some initial estimates. So it looks like across the valley, there's about a little over 900 acres that have come out in 2025. Again, that's not including land that was pulled in the last few years that's still sitting idle. And then some of that land has gone back in as of the last images that we looked at, which was September of of this So it's about 72 acres.

So whatever that net is, 800 and something. And then the graph on the map on the left shows you kind of in a heat map format where, you know, where those are by AVA across the valley. So how does this relate to to two things? One, extending replant concept, land coming out, you know, market conditions a little bit tough. What can you do to incentivize that to stay out a little bit longer and get some water savings?

And then that relates to re charge opportunities potentially on on some of that ground. So for recharge opportunities, how does it relate? So we've got this recharge investigation that we're working on. As I mentioned before, we kind of refer to it as a feasibility study. And it's looking at opportunities for increasing groundwater recharge.

We want to look at kind of technical, economic, financial considerations. The presentations that we just heard before us, think, are nice. They set up some of the things that we've talked about at TAG meetings with you all previously, and and I'll circle back to again today. So here's just a rough kinda outline for what is going into this report that we're working on, general overview of what these concepts are. We've got four recharge scenarios that we're calling them.

You can think of them as different alternatives. I'll talk through those today. We'd like feedback on those. Those are that's really, I think, what's interesting, like what what works, what's practical, what can we get implemented. A good chunk on technical and legal considerations, like what would you have to do under each of these scenarios, what water rights do you need, what's the process for getting those. Nick is going to talk a little bit more about that. As I mentioned, we've spent some time talking to folks over the last handful of weeks. I think I've learned a lot on those issues. And then just economic feasibility, what does this cost? What does it look like?

What are the what would incentives need to look like to get folks to participate? And then financial considerations, what are opportunities for cost recovery. We just heard about the recharge net metering concept. So I think some of those ideas can apply for some of the project scenario alternatives that we'll talk about today. So we've I think we mentioned that at a at a prior tag meeting, and it's something that we'll continue to to think about.

You know, how do you kinda get this to, you know, be be financed and and continue to work going forward? So I think I already covered this. I mean, we're we're working on kind of initiating all of these pieces. We've done some initial mapping, outlined the scenarios, got some spatial inputs that will go into the groundwater modeling, and then Nick will be working on the groundwater modeling some of the water right and legal considerations. Next. Okay. So what do these scenarios look like? There's a lot on the tables here. Let's just kind of step through them one by one. So we've got four scenarios that we're looking at.

Those are in the columns. And then if you go down through the rows, we've changed names a few times, so I might mix them up while I'm talking about them. But first scenario is extending plant recharge. That's just what we're talking about. You know, keep land out a little bit longer.

From an economic or cost perspective, the way I think about differentiating across these four scenarios is like the duration of the project and then the capital costs costs that are going into that. Like is it light earthwork or like a dedicated basin that's going to be there and keep ag land out of production? Those are two very different things with very different costs. So extending replant would be on land that, let's say, is is out, has already been pulled, right, and has not yet been replanted. Keeping that land out a little bit longer to and then figuring out ways to get water onto that land to increase infiltration.

So shorter term duration, maybe those are like one to three, one to five year type agreements you could think of. And then pretty light capital costs, just like don't do a whole bunch, just maybe burn up a little bit, hold water on the land longer. And then we'll talk about the kind of two primary water right pathways, working within existing rights or getting a permit for temporary underground storage. I won't steal Nick's thunder on that. And then, you know, who would administer that type of program?

Well, I mean, the GSA is involved largely, but, I mean, that could also be done by individuals. And there is a pathway for for acquiring water rights to to do that as well. Okay. Second scenario is direct on farm recharge. So kind of the you know, where you've where you're doing flood MAR or recharge basins.

So it could be on, like, working ag land. You know, we met with folks at who did we meet with? CSWA and I think a few others. I mean, there's a lot of issues with holding water on working vineyard ground and concerns with, you know, crop quality and keeping the roots wet that long. So some of the other ideas that have been floated are like, well, you know, kind of just during rainfall events, getting more water on the land, right, just kind of working with the natural system to get a little bit more water on on working ag land to increase infiltration.

So I think there are ways to do more of the flood MAR concept within this scenario that aren't just remove the crop, you know, and have a dedicated recharge basin, which is more capital intensive. And if you're not farming that ground, you know, everywhere, this is it's it's valuable land in the Napa Valley. I mean, like, that that's, those projects are probably more difficult to think of. Third scenario is like an in lieu project or a pumping reduction recharge scenario where you're using existing surface water rights where you have the ability to store in a pond or other location where you can, instead of pumping groundwater during the season, use your diverted surface water for irrigation and reduce your groundwater pumping. So that will be working within existing rights, pretty limited capital costs, more of a short term project duration.

But what that requires is the capacity to do that within existing rights. And there's a whole bunch of work that we're still working with individual landowners to understand a little bit better what the contours of that scenario could look like. And then the fourth scenario is, I think, kind of a combination of the others where you've got land that's coming out on a more permanent basis. It's targeted areas in the valley where groundwater modeling, let's say, shows you're going to get best bang for your buck. Maybe it's areas that are a little more marginal and like these could be more of the kind of capital projects, really like we just heard from the PV folks, you know, where it's, you know, a lower lying area that's got issues and you could, you know, dedicate it to recharge and get some other co benefits or multi benefit opportunities.

So those are the four scenarios. Spatially, how do those look? Know, because there needs to be some groundwater modeling done to figure out what these look like, at least conceptually. We've done some preliminary spatial screening, and I'll just step through them quickly for the four scenarios. So for extending vineyard replant, so you've got basically two criteria.

There's a point of diversion, POD, on the parcel, and then we're just it's a rough cut taking some of the older vines that are out there. And you recognize that you've got some that fall outside of the window that would you know, you're not gonna get, those aren't gonna be pulled and replanted. But, as an initial cut, just looking at some of the older vines that would, all else equal, be more likely to be replanted in the near future. So that's around 1,500 acres and then the heat map on the right shows how those break down spatially by AVA. Second scenario is a coarser screening.

To do on farm recharge, you just need a point you need a way to get surface water onto the land. So we've just looked at any parcel that has a point of diversion in the database that we have, and that's about 3,600 acres. And then again, you can see the heat map on the right and where those are located. And then the in lieu scenario or the pumping reduction scenario has a point of diversion on the parcel. And then we've also done mapping of the existing ponds or reservoirs across the valley, so the parcel needs to have both of those two elements.

So the ability to take water and then store that water for later use for this in lieu type operation. And that's about 2,300 acres across the valley. And then the fourth scenario is a stricter criteria, so you need to have a point of diversion, some of the older vines, so you're looking just as a rough cut at like water more land more likely to come out of production in the near future, and then a 1,500 foot buffer within significant streams. It's just a proxy for areas that you're likely to be closer to the waterways and generate some of the co benefits that I was describing earlier. So those are the four scenarios that we're working on.

That's those spatial inputs go into the groundwater modeling, and then we're working on the water right considerations as well. Nick's gonna talk through those two pieces.

Yeah. Thanks. So kinda different from the PD example, a lot of this would be contingent on on diverting water from a significant streams or other streams in Napa Valley. So we thought it'd be worthwhile to look into what is the the kind of water rights framework for for setting up those diversions look like. So just a few kind of big picture considerations is that, you know, you can't exist in, you can't augment an existing water rate.

So if you have a water rate for direct diversion for irrigation, you couldn't add on another water rate, for recharge within that same you can add another use to that water rate. Thinking about managed aquifer recharge, in terms of a water rate, recharge in and of itself isn't beneficial use. So the way we think about it is temporary underground storage of water for a later beneficial use. And then then that would be a new water right in most cases because most of the existing water rights are for for irrigation or frost protection or heat protection. So a pumping reduction type type of a a thing where you're storing more water, so you'd be diverting more water for irrigation, that would be a new water right, and those can be pretty challenging to get in the Napa Valley.

We'll talk more about that in a second. So the type of the water right, you know, whether you're doing a a water right for direct diversion for irrigation or frost protection, you know, that's kinda one bucket. And then the other bucket would be, a water rate, for temporary underground storage, so groundwater recharge for, again, some future use. So, yeah, talking about the the first type, which is the direct diversion for irrigation, securing or a new or augmented water right for direct diversion for irrigation is is difficult, it'd be time consuming, and pretty expensive. And it's Napa Valley falls in the the North Coast in stream flow policy area, and so it's especially difficult to try and get a new water right on one of these streams that are already appropriated already have kind of environmental concerns and other pressures on them.

The other kind of key thing is that these water rights are are held by individual landowners where a recharge type permit is usually held by, you know, some public agency like a GSA, county acting as a GSA or something like that. So for the direct diversion for irrigation, you know, the kind of the most feasible pathway seeing as a new water right is gonna be challenging to get is to to take advantage of existing water rights that aren't being totally utilized. So you have a water right for a 100 units and you tend to only use 60. You know, there's opportunity to divert more water and reduce your groundwater pumping. And then you could also change, how the existing ones are utilized.

So maybe you're diverting from a certain point of year storing and using that diverted water. If you could change, you know, maybe the timing or the amounts of when that occurs, there could be some some benefits for stream flow and and and reduction in groundwater pumping. So then the other type of permit would be a permit for recharge. So the first type would fall in, I think, scenario three, which is the the pumping reduction in in in lieu recharge, where this type would be a managed aquifer recharge type permit for a recharge basin, over irrigation, or something like that. So these are temporary permits, and they're actually not as challenging to get, especially if you're in a a watershed or a groundwater sub basin that has a drought proclamation, which Napa County has.

So there's actually a streamlined streamlined process for securing these permits, and the water board is actually kind of, you know, kind of promoting these, as a way of getting water. Again, it's it's for temporary underground storage. Recharge in itself is not a beneficial use, so you'd have to identify an a beneficial use for that stored water, which could be an existing use. So that could be pumping for irrigation or domestic needs, municipal. Again, you wouldn't be increasing the amount of water that your ground they're pumping.

You just have identified an existing use where that water that you recharge will get used. And that's a a pretty important distinction in in in how you set up these permits. A beneficial use could also be like an increase in low flow, so an in stream benefit, also considered a beneficial use. So, how you structure the permit, can be kinda there's there's some leeway in how you do it so that, you know, kind of things line up right and you're able to account for the water. One of the the key things, is you have to demonstrate water availability.

They don't want you diverting water when, you know, there's not enough water in the stream, to satisfy existing uses or other in stream considerations. And, again, so Napa Napa Valley Watershed is subject to that North Coast in stream flow policy, and they actually will figure out the water availability for you. So they'll tell you, you know, here's your permit, here's when you can divert, and here's how much you divert. And it's usually gonna line up with when flows are really high. So you you have a, you know, a flood concern or, in other streamlined permit situations, you'd be able to take 20% of the flow when the stream is at its ninetieth percentile.

But there's different considerations for if you're in the the North Coast in stream flow policy. Both those, the streamlined process and that North Coast in stream flow policy are actually linked in the PowerPoint. So if you wanna take a look at them, I think you should be able to do that. So that that kinda covers the water rights part. And I wanna get into modeling.

It's kinda starting with this aquifer recharge. So we have our existing model, and it's actually already being used by the state water board And they're modeling, looking at at at how they're what they're gonna do with water rights going forward. So we have a model that has every significant stream in the sub basin, and so we can use it to to kinda test feasibility. So, you know, Duncan might give us a list of parcels where, you know, this might be feasible. We can use the model to to, you know, show, like, what kind of recharge rates could we could could be maintained there, what type of impacts, whether it be to the the water table or vineyards?

And get a sense of, you know, how much water can go where. And then you can use the model kind of on the front end before you get these water rights to see what the benefits might be on SMCs and low flows in the Napa River and other, significant streams. And then you can use the model, to support, the water rights permit for recharge, so you can demonstrate a beneficial use. So if if you identify the use as in stream benefits, you'd be able to use the model and say, hey, we recharge this water and here's the benefit to the stream, which would be pretty challenging to do kinda without some sort of physical model. And then you also have identified the other beneficial use of groundwater pumping.

So we have an estimate of how much groundwater is being pumped every year. And all that kinda supports a water accounting plan that is required for any water. Right? So being able to demonstrate that that water that we stored temporarily underground is being used. And then modeling for the pumping reductions, and again, would be taking advantage of existing rights that are maybe underutilized or or could be optimized in how they're using being used.

Again, you know, for this water rights framework, the the groundwater model we developed for the GSP is being used by the water board, in their decision decision making support model, to better evaluate flows, and evaluate water rights. The existing model can maybe be used to show when, you know, since we have it's integrated and we have all the surface water flowing through it, we might be able to use it to identify periods where there's there's extra flow, and you could maybe divert at a different time and and and how that might affect, you know, how the pumping might occur since we know what the demand in the pumping. We have estimates of what the demand in the pumping are. And then kind of on the preliminary modeling side, we can use it to simulate the net increase in the version in on form starter. So we can actually plug in, you know, maybe some alternative strategies, where we're increasing the amount that's divert diverted and stored and and how that might affect pumping.

And then also look at it within the existing water rights, how the timing, could be optimized or the amounts we're taking out, could impact the low flows, which we're kinda after, improving. And then lastly, we can look at you know, we look at low flows, and then the SMC. So if we change, you know, in these existing water rights, if we're diverting more water, we're changing the timing, how would that affect the low flows, and the SMCs? So different data sources and information are being used to develop, these projects or management actions. So I think it's a discussion question which we can get back to.

You know, if you have any questions, insights, or considerations to improve and refine the development of this work. And I think I'll get into the next steps. Let

me kinda

that was maybe one, you know, question to consider. But so the the next steps are are to start evaluating evaluating water rights, especially in the pumping reduction framework. You know, maybe identify where water rights aren't being used all the way, and there's opportunities maybe to work around the edges to improve how they're being used to reduce groundwater pumping and increase those low flows. Getting into some of this preliminary modeling. It was discussed to see, you know, if we do these types of projects, what type of benefits could we see, you know, maybe playing around with where they're done so we can improve our understanding of where these projects might be most effective.

And then lastly is to, you know, consider partnerships, with landowners where, you know, recharge projects, the modeling suggests, and the water is there. You know, setting up those partnerships with specific landowners. For the application process, they want you to have a pretty good sense of where you're gonna be diverting water from and how much, before they even consider it. And then they'll determine the water availability based on those specific PODs and and how much water you're considering. So all that needs to be figured out with a model, and you have those partnerships, you know, semi good commitment from the landowner that a project is gonna go forward on their on their parcel, before you go to the waterboard.

So yep. And that's that's the last slide. So

Thank you. I had a couple things starting with the water rights considerations, kind of the core of this. So the the previous presentation we had, it seemed like they weren't running into an obstacle regarding the state. However, they weren't diverting from the mainstream. They were capturing surface water before it went into the mainstream.

So I was just curious if all the information that was presented today is interpretation of current regulations or if there was any collaboration with the state to understand how this could work in order to comply with the the GSA requirements.

So we we were focused on just the direct diversion aspect, not the capturing runoff. For our water rights assessment, I'm actually not a 100% positive that the water board would be involved if you're capturing runoff.

I mean, in my experience, it's all the same. It's surface water, and and it seems strange to me that there wouldn't be some requirement to allow for bypass going back to required flows needed to divert. But if it Working down there, maybe they're and she says they said that they were a partner. Maybe we reach out and and and ask. But but, also, you brought up the North Coast in stream flow policy, so maybe they're not subject to that and pretty so, and maybe that's maybe that's our hurdle here.

I I don't know.

Yeah. I mean, we were focused The the division we were talking to in the in the water board was looking specifically at direct diversions from streams. And I'm not I'm not sure how the the framework works. I think for capturing, like you said, capturing runoff, same kind of thing. And it seems like, you know, forming a partnership with the water board would be, you know, getting them on board for these types of projects might kinda maybe smooth that out going forward and and kinda figure out a pathway that's gonna work for those types of projects.

Thank you. Any other questions or comments from the TAG or staff?

You mentioned one of the slides you mentioned streamline processing under the temporary underground storage, managed off grid recharge. What is the streamline processing that

So in that, for permits for temporary underground storage, the state is trying to promote more recharge And so rather than going through the the traditional water rights permit application process, you know, they have a streamlined pathway now to try and promote these types of projects. In Napa, which is subject to that North Coast in stream flow policy, there's some additional caveats in that they'll tell you how much water is available. But long story short, if you submit an application for this type of permit in April, you'd be able to divert water that next winter. So it's not, you know, a decades long process that a a traditional water right would entail. The costs are very reasonable.

You can do a five year permit, and the costs are very reasonable. So it's just streamlined in the sense that they make it easier and they make it cheaper to do, and it's much quicker.

With regards to the land following idea, the Napa RCd would be interested on partnering up with some of the farmers who decide to do this to evaluate soil health before, during, and after. This is something that hasn't really been researched. And I am personally curious if done right, what kind of improvements in soil health we might see so that you end up with a veneer that is starting wood soils that can potentially retain water or move water more efficiently? Question mark. So if we do this and farmers are interested, I would be interested on doing some studies to determine if there's any differences between replanting right away or waiting a few years, doing sustainable farming practices in between.

Is there any thought on trying to measure what's getting to the aquifer or getting down kind of like they were doing in the Recharge project?

I think it's the I mean, that's part of what Nick's groundwater modeling. I think there's two well, there's two things there. There's this like, if you if you're gonna do kind of project by project like they were talking about, you know, at what level, and how do you set that up. And I think it kind of depends on which one of these recharge scenarios you're thinking about. And then from a sub basin perspective, think that was what Nick was speaking to with the groundwater modeling that needs to be done. You should be doing something that's getting a, you know, a meaningful benefit for

That we can we can bank. And we can bank against it.

Right. Right. So yeah.

On the replant and kind of extending the timing before replanting, are there any evaluation or consideration about what kind of incentive would kind of delay the replant? Or are we counting on only not having to pay the new fee those fields are not replanted?

Yes. I don't think the fee is high enough to get you there. So we have we have done we have we have done some analysis. We've got a lot of numbers on that. I I have not I don't think we've come here and kinda run those out. The minutes so I've got under a few different scenarios. It depends on what you're doing with the land while it's out. There's questions about, like, you know, soil quality. Like, what what are you are you gonna throw a cover crop on there? What's what's that require?

But so we've got some ranges of what an annual or a two year or a three year idle period would look like. Those things are really sensitive to two things. One, what you're doing with the land when it's out, and two, the price of of grapes that you're putting in there because that's the opportunity cost to keeping your land out longer. But we have done that, and we've also done just some rough calculations with OpenET that tie back to that the fouling maps just to, like, you know, how much water are we really talking about. So I I don't have all those pieces put together in a coherent way in my head right now, but we we we've we have been working on that and do have some ideas.

Yeah. I think eventually that'd be interesting to see kind of the the the cause that that will that will be per conserved, like, acre full of water as compared to doing some active recharge, like Mhmm. Somewhere somewhere else.

Any

other questions or comments from TAG or staff? Any public comment in the room?

Raffi with EGS. Just two quick comments. Firstly, I didn't hear any consideration of direct well injection as a storage rather than infiltration. Is that something that's not possible or wouldn't be allowed under water rights current water rights conditions? There are injection wells in the sub basin, the North end of the sub basin.

They've been operating for five or ten years. They're injecting used geothermal fluids that have had the heat extracted from it. So they're injecting back into the geothermal system, and that's they're all permitted through CalGEM. The other point that just want to bring up was that given the status of our economy at the moment, it is true that the vineyard business is not particularly good at the moment. But one should consider that it's also likely to turn around or it could turn around at any time and basically recharge plans on availability of land like that seems like a little risky.

Thanks very much.

Thank you. Do we have any other comments in the room? How about online?

We have one caller. David, you will have three minutes.

Thank you. I have a couple questions. Sorry there's a phone call I'm not going to answer in the background. Sorry about the distraction. So let's imagine this is sort of a thought experiment. I think it was Miguel who mentioned dry farming research progress on the dry farming understanding. Let's imagine a thought experiment. You have, say, 50 acres of a fallowed vineyard. What's the water balance difference between that and a 50 acre dry farm vineyard? So you got sort of in effect, you got three scenarios.

You got fallow, dry farm, and irrigated. So what what's what's the difference in the water balance of those sites? I I think that's an interesting question. On the flow regime, you know, we have we put water from drain tile back into ultimately, into the river. Is let's say, you wanna take water out, say, a mile upstream of where it's going back.

You don't own the the place where the water is going back in, but you wanna take water out upstream. Is that a scenario that's just gives the water rights folks too much of a of a headache, or is that

just

not I mean, because you're you're dealing with stream flow. It's just in a very different way than what people normally think about it. And let's see. The third question is about the this is maybe for Nick about the integrated hydrologic model. It drills down into the question I asked earlier about the biometeorology of water that's that's transpired by native vegetation in the watershed as a whole versus the detailed look at say crop evapotranspiration.

And as usual, I'll take my answer off the air. Thank you.

Thank you. Do we have any other online callers?

No other callers. Alright.

Thank you, Duncan and Nick. Appreciate it. Now we're gonna wrap it up. Jamison?

Get ready for 2026. These are always the moments when I have like these, like end of year, like, what changes do we want to make for, you know, the big picture kind of thoughts. So we're going to continue that discussion. Anyway, thank you to the TAG members for your work this year and of course to our guest presenters, our regular presenters, our technical team, everybody thank you. The public who stayed through the whole thing and still have interesting comments and points to make. So hope everybody has great holidays. Any last comments from any of you before we adjourn? No. Okay. Great.

Meeting adjourned. Thank you.

Thank you.