Water Resources Podcast - Karen Guz
[00:00:22] Bridget Scanlon: I'm pleased to invite Karen Guz to the Water Resources Podcast. Karen is the Vice President of Conservation at San Antonio Water System, SAWS, and serves on many state and national water committees, including the Technical Education Committee at the American Water Works Association, and also chairs the Water Conservation Advisory Council for the Texas Water Development Board.
Thank you so much, Karen for joining me today.
[00:00:51] Karen Guz: Thanks for having me!
[00:00:53] Bridget Scanlon: I think today Karen focuses primarily on conservation, but we're probably going to have a bit of a broader discussion on water demand projections relative to supplies and emphasizing droughts and the importance of conservation. SAWS and San Antonio are really unique in their, initially in the mid nineties, their heavy reliance on the Edwards Aquifer groundwater focus, whereas when we look at other cities like Dallas and Houston, they mostly rely on surface water. Austin too, where I'm from.
Heavy reliance on ground water, serving about 2 million people in San Antonio. And I really appreciate all the effort that you guys put into publishing the water plans and they're fantastic. So, the recent water plans indicated that SAWS used 71.5 billion gallons. That's about 218,000 acre feet in 2024. Karen, maybe you can provide some background on SAWS and how it has evolved over the past decades and diversified its portfolio.
[00:01:57] Karen Guz: Our annual production's a little higher than that, in acre feet, but it was in 2024. A key thing about San Antonio is that, about three decades ago, the very first water plan came up for San Antonio. We were facing the reality of limits of how much we could take from the Edwards Aquifer.
Things were rapidly evolving. There were lawsuits over endangered species, and so city planners were smart and realized San Antonio's going to have to become a front runner in water planning. We are going to have to diversify. We're going to have to develop recycled water resource, and we're going to need to view conservation as a supply. So that first plan, that I believe is in 1993, suggested we needed to do all those things- set per capita reduction targets. All of that has just continued to get more sophisticated. We have successfully gotten to a point where we were a hundred percent Edwards aquifer. And then last year about 60% of the potable water that was served to customers came from the Edwards and 40% from other supplies. A huge evolution in how we manage water for our customers.
[00:03:09] Bridget Scanlon: And of course, in San Antonio, you've seen a big increase in population since the mid nineties to now, and currently serving 2 million people. That's a real challenge, I'm sure.
[00:03:19] Karen Guz: A lot of Texas is having really robust population growth. The whole I 35 corridor and our population growth has been impressive in the past five years. It surpassed what we'd expected in our last water plan. It's a good illustration of why these plans need to be updated frequently, because you take best available data and then things change.
We have robust population growth. We're expecting that to continue, and of course that means you have to look hard at how much more water will we need? How much can that be offset by conservation? So it's a relatively complex analysis to answer the question. If we try to look in the near term and the far term. Will we have enough water given the conditions that we expect, including drought, including population growth, including the reality of reduced water supply, some of our water supplies being curtailed.
[00:04:16] Bridget Scanlon: Karen, you have helped me recently in this project that we are doing for the Texas Water Development Board. Where we are looking at the reliability of their population growth estimates, and their water demand projections. Many utilities and the state look at projected population growth, and then gallons per capita per day, GPCD to estimate water demand.
When we were talking to Austin Water recently, they suggested that they were not strictly following that approach because they have some big users like Samsung using 2.2 billion gallons a year. UT Austin, I'm ashamed to say, using 700,000 gallons a year. But I guess Samsung recycles half of that water.
But still how would you describe what is the best approach, and how can you try to develop these projections?
[00:05:06] Karen Guz: I think Austin and San Antonio are ultimately getting to a similar place of a more nuanced understanding of where our water's going and how much we're going to need. We do use total per capita as a big metric in our utility. It's easy to understand, it's easy to report out on, and it includes all of the water put into production, including water losses.
So it's a really useful metric to track and a critical one, but we need to break it down to be able to show very clearly. Let's break out that total GPCD. How much of it was non-revenue water, how much was single family, multifamily, industrial, regular commercial landscape irrigation? All of those groups that we can track in a detailed way in terms of number of accounts and usage per account, in our modeling for demand, we do that. We forecast out all of those in terms of the number of accounts we expect to have and the usage per account. But because things can change, you have to really look closely, not just at the total GPCD, but at that breakdown every year to check, were our assumptions reasonably correct?
Did something significant change? Did we suddenly get an influx of new industrial customers who changed the total GPCD. We need to understand that. So I think Austin and San Antonio are looking at a similar need for detailed understanding, but maybe going at it a little differently to get to the same place.
[00:06:36] Bridget Scanlon: I was listening to NPR yesterday and they were talking about data centers in Georgia and their need for the land and water and things like that. And I was just Googling and looking at San Antonio. I mean, there was a map of data centers. They listed about 50 in the vicinity of San Antonio.
And then I saw another thing indicating Denver Vantage Data Center, 430,000 square feet being proposed and looking for a permit in San Antonio. Do you see increasing data centers being something that you will have to pay attention to in the near future?
[00:07:10] Karen Guz: We have to pay attention to everything. We have the ability right now to break out our commercial accounts by North American Industrial Codes, N-A-I-C-S codes, so we can pull up what relative use is by different types of commercial industrial customers, including data centers. As of today- I'm sorry, I'm not going to remember off the top of my head how many accounts we have that are data centers. Their volume, if I were to recall that exact figure would sound really high- but you have to remember, we produce in a winter day, 225 million gallons a day. And in the hottest summer days, sometimes over 300 million gallons a day. The data centers have not yet reached a point where they're even a huge percent of our commercial usage.
But that doesn't mean it's not something we would pay attention to. My impression is that a lot of the data centers are located outside the SAWS service area. So they may be in the San Antonio vicinity, but outside the SAWS service area and providing water a different way through a different water provider or their own wells.
My impression is also that this gets them access to cheaper land and other things as well. We may get more in our service area. Certainly, whatever water they're using is important, whether it's SAWS water or adjacent wells that are coming from the same source.
So it's certainly a trend worth watching.
[00:08:38] Bridget Scanlon: Even though I mentioned early on that you know, in the mid nineties you were almost completely reliant on Edwards aquifer, which is groundwater. Edwards is a karst aquifer type system, so it has a lot of the similarities to surface water systems. It responds rapidly to drought but then it also recovers.
So some people are very impressed that the news reports the water level in J 17 every evening, so people have a feel for the conditions of the aquifer during drought. In your water plan then you mentioned that you consider a hybrid synthetic drought that considers the fifties drought and more recent 2011 to 2014 drought.
How did you come up with doing that hybrid, nine year drought?
It's kind of like how much insurance do you want to buy?
[00:09:25] Karen Guz: That's a very good way to look at it. It's a lot debate frankly, between a lot of people who are very intensely involved in the water planning and operations to say how harsh of a scenario should we plan for? I've been at SAWS for 25 years and I remember way back when we were first planning for the nine-year copying the drought of record. This is well before 2011.
I remember there were people in the room saying, "Oh, that'll never happen again. We're not going to have a drought that bad." And they were shot down and we kept planning for the drought of the fifties, by the way. And then 2011 happened across the whole state and it came on faster and harder than the drought of the fifties.
I think nobody is saying that anymore. And now we're in a drought that this is the sixth year of it. And we, on a biweekly basis, are comparing it to the drought of the fifties. We've had rainfall deficits somewhat similar to what happened over the prolonged period, and our aquifer levels are slightly higher than they were at this same point in drought in the 1950s which speaks well of the regional water management.
We have so many more people and industries using that water, and yet in the sixth year of drought, our aquifer levels are not as low as they were in the sixth year of the 1950s drought. It's a bad drought. This is, I would say, the worst since the 1950s in duration and intensity. But water management really matters because it has not been a crisis remotely in San Antonio.
It's something we manage, we work very hard at. I'm amazed really at how well it's going, considering the severity and length.
[00:11:11] Bridget Scanlon: Anytime I hear about a drought, I pop up the US drought monitor data. And look at the state or different regions. Looking at the state US drought monitor, the time series, how bad is it now relative to the past? In the state drought monitor, you can see 2011 was horrendous.
And then-
[00:11:30] Karen Guz: Across the state. Yeah.
[00:11:31] Bridget Scanlon: Right. And lasted until about 2015, one of the wettest years we had on record. You know, you had the Wimberley floods in the May and all of that sort of thing, just north of San Antonio. But when you look at the county level drought, the US drought monitor for Bexar County, you can see the impacts of these recent years in drought.
[00:11:50] Karen Guz: And I appreciate that somebody else is noticing it other than those of us in San Antonio. I have worded it to people that Bexar County, our county, has been just particularly unlucky in the last six years. When we look every week at that US drought monitor, you see this just red bullseye either over Bexar County or just to the west and north of us, which is our recharge zone.
So it's just our friends in Austin, your area, you've gotten significantly more rain over that six year period than we have. But that's classic San Antonio. We are in a part of Texas where we can get those tremendous rain sometimes or be influenced more by the west dry Texas and have these prolonged dry periods.
[00:12:35] Bridget Scanlon: I recently interviewed John Nielsen Gammon, and how can we predict these long-term droughts, and how can we predict when we're going to get out of one? And he said it's very difficult because, as you said, Austin has had more rain.
They filled the reservoirs, the Highland Lakes-
[00:12:52] Karen Guz: But they did not fill the Edwards. We had a lot of opportunity to nerd out over recharge zone and where the rain falls. Understandably after those droughts, we had people asking,
"Well, isn't the drought over?" And so we got the opportunity to talk about watersheds and where rain falls and where does it go. The rain fell in areas where it really went to various reservoirs, like the Highland Lakes.
We had some rain over our recharge zone, but not remotely enough to break the long-term 50-inch deficit of water over a six year period. Our aquifer went up a bit, but we've had rain events that hit in the sweet spot and had the aquifer go up 10 feet or more in a few days. That did not happen because the rainfall in our recharge zone was unimpressive, relatively speaking.
[00:13:44] Bridget Scanlon: It's great to be able to see those data J 17 Comal Springs and to look at the impact of these different rain events and see if it's translating to aquifer recharge and response. Getting back to gallons per capita per day, you have come a long way and it's extremely impressive. So I was looking at some reports and they mentioned early eighties, like 225 gallons per capita per day. Then '92, 154. Then the most recent five-year average, 116. That's like a 50% decrease. You're projecting that it will go down to maybe 87 GPCD by 2075.
Can you describe some of the main controlling factors on this GPCD and how you are working with that, trying to improve it?
You know, you mentioned you emphasized conservation, and I think that's the least expensive way of water supply.
[00:14:41] Karen Guz: It is.
[00:14:41] Bridget Scanlon: I often think of managing water as like a bank account. You manage your inputs and outputs and you store and your transport and all of these things. Reducing your demand is probably one of the least expensive.
Maybe you can describe the GPCD for us.
[00:14:57] Karen Guz: I want to put it in perspective a little bit, and since SAWS was created when our GPCD was 154, down to 114 last year. If we were today at our population levels today, still using 154 gallons per person per day, we would need another 90,000 acre feet a year. Which, we brought in a huge project Vista Ridge years ago. We would need two Vista Ridge projects and we would need them immediately. So it's arguably true that conservation has been the biggest source of water supply since SAWS was created, in terms of making more water available to new people.
Now, the strategies we use to achieve that are education. Getting people to care about water and understand it and think they can influence things about it in a positive way. Incentives to get people to make permanent changes. And then regulation is really important. We call it reasonable regulation. We find things that makes sense and are impactful and cost effective and don't interfere with quality of life. The specific things we do in those three areas have changed over the years.
Early years, we were all about getting rid of high flow fixtures. Toilets, faucets, aerators, all kinds of things. Restaurant free rent, spray valves. We declared victory over those at a certain point, we did hundreds of thousands of toilet change valves and had to say, "Okay, we've achieved that. We need to move on." Today we recognize that all conservation is important, but we've achieved a fairly low indoor per capita of in the forties, on average, for indoor single family. It's going to gradually reduce more, but the importance of helping people have landscapes and their homes and businesses that they don't feel they need to water a lot when it gets hot and dry. The strategic importance of that can't be understated. The variability in GPCD is a very expensive problem. We really put a lot of emphasis on that.
The other thing that is going to be really important going forward is being even more data-driven than ever before. Using new tools that we have, for example, find customers who have problems. That their electronic meter shows something has suddenly changed, so we can get with them quickly before they get a bill, and save that water that's being wasted.
Finding outliers among each kind of customer on a regular basis, and again, getting with them quickly to offer help. So we're going to continue on that landscape outdoor water use pattern, and we're going to be mining available data analytics that we just didn't even have five years ago.
[00:17:50] Bridget Scanlon: That's amazing. We don't water our lawn, basically, we have weeds.
[00:17:54] Karen Guz: Well, you could have resilient plants! One of the things that makes me cringe, that I'm going to take the opportunity to say. Is that we talk about resilient water saving landscapes. I try not to use what I call the X word, Xeriscape, is spelled XERI and no one knows how to say it. I cringe every time I hear someone say, I have a zeriscape. You'd be so happy with me, there's nothing but rocks.
And I cringe because, if you want all rocks, I don't want to be the taste police. Have all rocks, if that's what you want. Knock yourself out. But it won't be as easy to take care of as you think. It's going to have weeds in it. It's going to hold heat.
We promote living landscapes that have very resilient plant material that have other benefits to the ecosystem we live in. In this drought, it is helping reinforce that as people get tired of trying to manage grass in high heat areas. We see it going away in parking lot islands. We see it going away in high reflected heat areas, and home landscapes, and people, even more than ever making different choices.
[00:19:00] Bridget Scanlon: It is fantastic that you've gotten the indoor water use down to the forties GPCD gallons per capita per day. That's amazing.
[00:19:07] Karen Guz: New homes in Texas have had high efficiency toilets for quite some time. We mandated EPA water sense standard fixtures in 2007. So we've made a lot of strides. We do have a challenge that's unique with our hard water from groundwater. A lot of people choose water softeners and we're going to have to work to discourage that.
Those cause environmental problems that salt goes into our ecosystems. And then also it increases the indoor use by about 12% when you have one of those. We are working hard to, we're going to be even more and discouraging that. The indoor usage, I think generally, especially with the new meters, is going to keep going down as people identify leaks and then repair them quickly and understand their usage patterns.
What really can make the residential GPCD so variable is whether or not people water a lot outside, that can be 70% of their water use.
[00:20:04] Bridget Scanlon: When I was talking to Newsha Ajami in California a while back, they indicated in some of their reports that the new homes had less water use than the older homes. But when I look at some of the graphs that you have, when you look at the water use by the age of the home it seemed like you were showing an increase in water use with newer homes.
[00:20:25] Karen Guz: It's not a perfect relationship because the peak of newer home use came actually in homes built in the 1990s. So back in the fifties, sixties, seventies, eighties, homes never came with automatic irrigation. Only a few estate kind of homes came with that. And then around the late nineties, early two thousands really, then we started seeing automatic irrigation going in.
And we had some very big gated community properties, established larger lot sizes, and now those irrigation systems are quite old and probably need to be replaced or retired. Those homes actually use the most water. They have big lots in an aging irrigation system that was put in when standards weren't then what they are today. But still, brand new homes, if they have automatic irrigation, will use more water than those homes built in the earlier decades.
So it's old and new is a relative term. And we've replaced so many toilets that those older homes don't have that anymore. They're equivalent on indoor usually to new homes. It's an interesting pattern where I point out to people, new homes are especially likely to have that water softener.
They are more likely to have a pool and they're more likely certainly to have an irrigation system. And those optional things that automate uses of water really drive up the usage patterns of single-family homes.
[00:21:59] Bridget Scanlon: I'm glad that our homeowner’s association is not too stringent on landscaping like that. What role do you think homeowners’ associations have on water use or requiring homeowners to have?
[00:22:13] Karen Guz: I'm really glad you brought it up because things have improved a great deal on that front. An interesting thing people don't generally realize is that homeowner associations have bylaws. Deed restrictions in their rules that were established often by the developer who used some boilerplate, HOA list of bylaws and rules.
And those are very hard to change. You need some huge percentage of homeowners to vote to change them. So you may have this old weird requirement in there that grass has to be kept green and replaced if it's dead. You had some HOAs where all they needed was one or two people really raising a ruckus and saying, this is in the rules. You have to enforce it.
The HOAs would feel compelled to send out what we were calling nastygrams, saying you have to have green grass or you have to replace your grass during a drought. San Antonio passed a local law, years ago, that you may not insist on grass nor may you require someone to water it. This supersedes anything in your bylaws of the HOA.
Now, the state of Texas passed something similar. They specifically said, you can't demand that someone replace grass during drought and you have to give them till, I think 60 days after the drought ends. The effect that we have seen when we talk to HOAs is a lot of them seem, frankly relieved. We've talked to a lot of the leadership and they're saying, oh, thank God we can stop talking about that.
It's because the laws now make it clear you can't enforce this old thing that's illogical in your bylaws. So we've had really good conversations in this drought with HOAs to say, let's help you determine how you give people instruction about how to take care of their water saver landscape. It's different than grass. So we can help you, because they don't want a weedy mess.
And so we get that. They still want to have aesthetic standards and we get that. I feel that with this change in law, the water utilities have a great opportunity to have a positive partnership with HOAs.
[00:24:16] Bridget Scanlon: Well, I had no idea. That's absolutely fantastic.
[00:24:19] Karen Guz: It's just great news. We invited HOAs to come meet with us last year and we offered them a deal. We bribed them. We said, guys, they're always short money, so how about if we'll pay you a nominal amount. If you will share messages from SAWS in the drought. And we will work together to promote landscape changes and we'll even list on our programs. Here's a link to this HOA, so you understand if you have to turn in a plan to them or whatever. And we had 70 HOA leaders show up to talk to us. The meetings we had were very positive.
[00:24:54] Bridget Scanlon: That's amazing. So, another thing Karen, that we chatted about in the past, I think you mentioned that you talked to Robert Mace. If it's a wet year and we have a lot of water, why not use it? And we don't have any restrictions and why not do it?
But, my feeling is then it's very difficult for those households to ratchet back then during a drought. I know we have drought regulations and different levels of drought, but when I walk in the morning, I see some people watering every day.
[00:25:22] Karen Guz: I think that's not allowed in Austin. Hopefully somebody starts enforcing on that. There's a system to warn them and get them to stop that. But you have to meet people somewhat where they are. And there are a lot of people who have said that they think San Antonio's ready to have year-round rules that no more than once a week should you run your irrigation.
And then, you have other conversations where people find that just illogical overreach. if it's raining a lot and the aquifer's high, why can't I pick when I water? Why are you forcing me to do it on Friday which I hate. I want to be able to do it on Tuesday, whatever. I think there's a nuance of reading the room and figuring out when is it a reasonable regulation and when is your community thinking you're taking it too far?
Because if you don't get most people on board, you can't regulate them into compliance. They have to mostly agree with you. So our tack in San Antonio so far, and this could change, has been you may not waste water. That's always illegal. You may not ever water in the middle of the day. That's always illegal.
But the rare times when we are not in drought restrictions in the summer, which frankly a lot of times we are, you can choose your day water. We're going to always advise you to water no more than once a week. Just for the sake of your water bill. Why would you want to spend the money if you don't have to?
And a lot of people follow that advice. And then when we go into drought periods, we mean it. I don't think there is any other utility I've ever talked to that consistently does the level of enforcement we do in San Antonio. We warn people based on seeing that they're violating with the AMI data and we have 25 part-time people driving around all hours of the day and night catching them.
We'll have thousands of violations. Most people don't violate twice. So violations really work. It's not pleasant, it's not fun, but it works. Okay, we'll let you choose your watering day when we're not in drought. But boy, when we are in drought, we really mean it.
[00:27:22] Bridget Scanlon: That's great to have such enforcement because, I think that's very difficult. Being reliant on groundwater and the ups and downs with wet and dry cycles, you have done a lot to diversify your portfolio, which reduces risk. And I'm so impressed. And I really enjoy reading the water management plan where you describe all of these different sources and the transparency and you know how much water is coming from what sources.
Maybe you can describe a little bit about how that has evolved, how you have developed these different sources and how that makes you more resilient.
[00:27:55] Karen Guz: San Antonio arguably has what has been described as one of the most complex water systems in the United States. We have over 150 wells from the Edwards all over the place, so just that's complicated. We have these 15 different projects from, I think it's eight different water sources. I just want to give some credit to our operators, the people who make the system work. We make it sound simple when we say, "ah, we're just going to bring back water from aquifer storage and recovery. We're going to turn up brackish desalination. We have a little bit of Canyon Lake water. We got a little bit of Trinity water. We've got Carrizo water from these places."
We make it sound so simple to turn those on, but someone has to continually manage the integration of those supplies. Make sure the chemistry is what it needs to be and that the whole system keeps working. The amazing part of it is that a few times we've had something go wrong.
So although it's complicated, if something goes wrong, we can flip. And again, I'm going to make this sound easy. The operators are amazing. We've had a crisis happen at our H2Oaks facility, which is where ASR brackish, desal, and some of our Carrizo comes from. We had a lightning strike hit. A couple years ago, and that went down. Customers never realized because they managed to divert to other supplies.
Another time, they had a leak in the line for Vista Ridge and needed to shut that down for some repairs. Again, customers never knew. It is an amazing system we've got. It's not easy. Those supplies are all expensive projects. They're all capital projects. There's always somebody who's objecting, I think, to every water supply project that you want to do.
In our future plans, it's interesting that we're building on the success we already have. Knowing that we can expand brackish desalination in South Bexar County going into a different aquifer we built the first plant so that it could be doubled in capacity. That's something in our future plans. We can increase the amount of water we can bring back and forth from underground storage in the Carrizo. We call that aquifer storage and recovery.
So we have some really good options going forward because of our experience with these projects.
[00:30:18] Bridget Scanlon: That's interesting, and Karen, when you said that you managed the chemical compatibility and everything. Because I think in Tucson, Arizona, when they started take bringing in Colorado River Water, everybody was going around wearing orange shirts.
[00:30:32] Karen Guz: Yes. That's one of the things that irritates people. It's not dangerous, but you can have iron precipitation. Then when you're washing your clothes, you get orange spots or orange clothes. Our people in resource protection are wonderful chemists when it comes to helping prevent that annoying problem or more serious problems.
You don't want the pipes to descale. That's what happened in Michigan years ago. They brought in water that the ability to descale calcium from pipes and then lead started leaching in. Although we don't think we really have a lead problem in San Antonio, we don't want pipes to be impacted when we change the chemistry.
[00:31:13] Bridget Scanlon: Right, The Flint, Michigan case. Looking at the most recent water management plan, I think, about 50% was from the Edwards 160,000 acre feet. And then, to manage the wet and dry cycles, then storing water is fantastic. When you built your aquifer storage and recovery system that was amazing.
When you could get more water from the Edwards and you didn't need it, then you transported water to the Aquifer Storage and Recovery System and stored it then, and then you could bring that out during drought years. So I think in 2024, that accounted for about 8%. ASR accounted for 8%, and so you're storing it in a porous medium, like the Carrizo.
You also manage wastewater and treated wastewater. It was about 17% of your water I was really impressed with how much treated wastewater is used for your energy system, CPS energy. It is all recycled wastewater. That's amazing. And then you've got regional, porous, medium Carrizo-Wilcox, and then you have Vista Ridge bringing water from the Carrizo Wilcox with a long pipeline. Everybody is very interested in recycling water more and more.
The portfolio of options that you have reduce your risk then of water shortage. It's almost like managing an electricity supply because, in electricity, supply needs to meet demand instantaneously. The way you are able to flip switches and your operators are so able to manage all of these different systems, that is amazing.
[00:32:42] Karen Guz: it is amazing. The recyclable water system was one of the very first things that SAWS started working on in the early nineties when it was formed. And honestly, SAWS was formed as an entity, from what was previously different water agencies, in order to facilitate bringing together wastewater, water, and recycled water work. In order to facilitate working together to do a recycled water system.
And so are fortunate that came together. And we're fortunate that several of these supplies like the Vista Ridge, which is Carrizo, brackish desalination, and other Carrizo projects have been so successful.
I think aquifer storage and recovery is one of the coolest things, because we don't always use all of our permitted water in a year. I explain it to people that there's no rollover minutes. We have a certain amount we can use of Edwards in a year, and if we approach the end of the year and we haven't used all of it, we're allowed to use for the year we store it.
Interestingly, even in this year, we are on track to have a lower per capita than last year. We have managed to bring back so many non-Edward supplies that it looks like we might be able to store at the very end of the year. That's an amazing thing to be at the end of this year of drought and say, oh, we may have another 5,000 acre feet we didn't use. Let's put it into aquifer storage and recovery. Let's bank it.
Like you said, it's like a savings account. Let's put that water in the savings account. 'Cause it doesn't look like this drought is ending. It looks like it's going to go on at least next year.
[00:34:22] Bridget Scanlon: So that's fantastic. And then the fact that you manage the wastewater also, I think you've got about three main wastewater treatment plants and so that offers an opportunity then. And you have been using the recycled water for CPS energy, and that's the main electrical utility in San Antonio.
You have the potential to expand and you have the purple pipe water also.
[00:34:44] Karen Guz: There is. Now, an interesting piece of trivia for you is that conservation in early years was not taken into account by the first planners of the recycled water system. To their credit, conservation was fairly new back then. We were starting all these new initiatives and no one really knew conservation would work so well.
And the effect of it for decades was that if you look at a graphic of the volume of effluent we treat, it didn't go up for 20 years. Even though our population kept growing and growing. And the reason that was happening was that conservation was decreasing the per capita use so much that we were treating less effluent.
Now, we are starting to see with population growth, that volume of effluent go up. We've also gotten some more certainty in how we can have a permit to put some in the river. And make sure that it stays in the river and makes it all the way to the bays and estuaries. We use water for environmental flows.
Which is sometimes it's the only flow south of San Antonio down to the bay. We use it for power for our sister utility, CPS Energy. They use it in their cooling lakes. They also need potable, by the way, to turn the turbines. They can't get away from all potable use. And then we sell a lot to direct use customers through the purple pipe system.
There's more we can sell. We try to go for big volume customers. That's the most efficient way to use it. We don't send it to the neighborhoods, to water lawns. That's discretionary on and off use. We want to use it for big customers that are driving our economy or for big community resources.
We're building a new arboretum in San Antonio, and the arboretum was intentionally located in a place where they can use recycled water.
[00:36:32] Bridget Scanlon: The Texas Commission on Environmental Quality, TCEQ, is now developing new regulations to use treated municipal wastewater for aquifer storage and recovery. Having those regulations that a possibility is another opportunity to expand the use of recycled water.
I wonder, right now your wastewater treatment plants are treated to tertiary standard. What would be required to treat it for aquifer storage and recovery?
[00:37:01] Karen Guz: I'm afraid I don't know the answer to that question. We treat our wastewater to a fairly high level. I don't know what the regulations are looking like for, if you want to store it in ASR and pull it back out and drink it. That's an interesting question. I have not heard conversations about drinking the affluent at this point in San Antonio.
And I want to point out to anybody listening, it's not as icky as you think it is. I got a chance to be in Namibia years ago. They have the world's largest effluent to potable treatment plants. I got to see it. I drank the water. That's like a huge percentage of the water in the largest city there, Windhoek that they use.
So it's very doable, very clean water, but it's also expensive. A lot of times I think they're essentially running it through a reverse osmosis. If you're going to RO it, you might as well drink it. I haven't heard conversations about that in San Antonio. I'm hearing more building on the successes we've already had. Like expanding brackish desalination and the aquifer storage and recovery is our next things.
It's not to say we'll never get to that other point, but in the near term, I think we're sticking with tried and true.
[00:38:09] Bridget Scanlon: Yeah, I was reading about the Namibia Windhoek, and I was familiar with what they had been doing for decades. And I think they were listed as a sister city to San Antonio too.
[00:38:19] Karen Guz: They are. And that was how I ended up being in Windhoek because of that Sister City relationship it's fascinating. To them, we look washed with water.
[00:38:31] Bridget Scanlon: Right. Right.
You mentioned to me in the past Bruk Berhanu, who is now working with the Pacific Institute. I know the Pacific Institute has a nice report on the potential for using stormwater in urban areas. And Texas ranks top on the availability of stormwater because of the rainfall, and the degree of urbanization, and everything.
In that report, they mentioned maybe 50 to a hundred thousand acre feet a year in the San Antonio area could be potentially accessible.
Any thoughts on stormwater?
[00:39:04] Karen Guz: Well, I think stormwater, it's an interesting analysis they did, by the way. I really appreciate the great work of the Pacific Institute. I often have people say, "Well, I saw that rainwater flow by my house. And I'm so upset we couldn't grab it." I'm sympathetic, I hear them. However, it's much more complicated to collect all of that storm water than they think it's going to be because it's so dispersed and you need a very large storage area to capture our feast or famine, rain events.
I think almost half of our water fell in four rain events this year so far. We have very unreliable rain. We do not get reliable rain events. So that means you need huge storage, and then how are you going to clean it? So it is not as simple as saying, like "Just put it in the recycled water pipes."
No. That would degrade the quality. You would have to treat it. Storm water can have a lot of oils and other things, contaminants it picks up. It needs treatment. I'm not trying to poo-poo the idea, I'm just pointing out it is not simple. I also remind people that we have an incredible stormwater capture if the rain just falls in the right place, in the form of the Edwards Aquifer.
There have been aquifer recharge enhancement features that the Edwards Aquifer Authority has developed to help direct more rainfalls into areas of high recharge. I also think that the style of landscaping has to change in the future. We need to do more of what I think of as organic rain water harvesting. Design your landscape in a way that it directs the water to slow sink in, so you're storing it right there in the soil.
I agree there's a lot more potential for managing water better that just falls from the sky.
[00:40:50] Bridget Scanlon: We here at the Bureau have been looking at high magnitude flows and so have colleagues in University of California Davis. And in some years, there's enough greater than the 95th percentile stream flow in Texas, than how much we use in a year.
But as you say, the logistics-
[00:41:08] Karen Guz: where are you going to put it? And that is not a simple question. Some well-intentioned person once mentioned something about a new stormwater collection project being at one of our most beloved, oldest parks in the US, Brackenidge Park. And is that going to be a big water supply project?
And I said, wait a minute. I've never heard of anybody destroying Brackenridge Park for a reservoir. What are you saying? And all he meant is that there's going to be a rain garden there. I said, oh, okay. That's more to me, a conservation measure than it is a water supply project.
[00:41:40] Bridget Scanlon: Karen as SAWS and as San Antonio has evolved, increasing the population now to 2 million and projected to, I think three and a half million by 2075 or something like that, having this portfolio of options then for water, you have also water markets, which I find really impressive.
I was talking to Todd Votteler recently, the water markets the SAWS has and the relationship with, agricultural irrigators, so you can purchase water from them during drought years. The Vispo Voluntary Irrigation Suspension Program, all extremely impressive.
so developing this portfolio, it increases the cost of water and you benefited from having very low cost, very low baseline cost because you didn't have to treat the Edwards water. Then that puts an emphasis on trying to accurately project demand because you don't want to have too much supplies because you have to pay for these, but then you don't want to be caught short.
[00:42:37] Karen Guz: It's a very tricky business to be in that if Mother Nature starts supplying people stop using that discretionary water. If it doesn't rain for 30 days or more, people really want more of it. you really take a tack of doing both of mitigating how much that per capita shifts in the dry year.
We can't stop it from going down in a wet year because people just stop watering. It rains a lot in the summer like it did in 2021. Our GPCD was 111. That was because we had nice timed rain in the summer. We can't stop that. That's 'cause it's going to happen 'cause people are smart. But we try to mitigate how much it goes up.
When it gets hot and dry. And we do that with regulations and education and incentives. Then we know, okay, it's just going to go up a little bit when it's hot and dry sometimes, and we're going to have more people. The combination of modeling all that tells us when the next supply project needs to come on and how big it has to be.
[00:43:37] Bridget Scanlon: That's impressive also with your planning. You have short term, medium term, and long-term planning. And then you revisit that planning every five years.
[00:43:45] Karen Guz: Because things change. You have to make assumptions of how many people will have and how much water they'll use, and obviously the population changed a lot. That's a great example of why we need to update everything about every five years because water supply projects, take a long time.
They don't get accomplished one year to the next. It is very important that you know in advance, and one of the things conservation does is give you more time before you need that capital project.
[00:44:13] Bridget Scanlon: I know no city wants to face what Cape Town faced many years ago. With Cape Town Day Zero and all of that sort of thing. So having this portfolio of options, surface water, ground water, storage, all sorts of things, water markets really reduce your risk and helps you avoid those sorts of situations.
Thank you so much for the talking with me today, Karen. I really appreciate it. Karen Guz is the Vice President of conservation at the San Antonio Water System, and good luck with the all of the future plans.
[00:44:46] Karen Guz: Thank you, Bridget. Appreciate you having me.
