Chris Higgins: It's a phenomenon. It's like a natural phenomenon.
Don Hood: It's a "Femininomenon"
*laughter*
Chris Higgins: Do be do be do de … Phenomenon.
Clay Sellers: Got questions about the Brazos? No more unknown. Ever wonder where that water comes from or where it goes? We're Unpacking the Brazos River.
Charlie L. Shugart: Okay. Quick pop quiz. I'm about to ask a question that sounds like total trivia night bait, but I promise it matters. Who do you think is actually using the most water each year in the Brazos River Authority's water supply? If you just muttered under your breath, “Big corporations,” or “People watering their lawns in July,” I mean valid.
And if your honest reaction to that is a giant shrug because you have absolutely no clue where your water even comes from, no judgment here. I didn't come out of the womb ready to present a dissertation on the impact we have on the future of our water supply. I had to learn this stuff from scratch too. Water supply in Texas has been all over the news lately, so let me give you a quick scope of the area the BRA covers because it's not just what's along the Brazos River. We're talking about the North Bosque River, Leon, Navasota, Salt Fork, and several others, which means, of course, we're not just talking about Waco or Granbury.
76 counties fall within the Brazos River Basin. Some of those are entirely in the basin while others are like just barely. So, who or what is using most of our water? I'm Charlie Shugart, and this is Unpacking the Brazos River. Returning to the pod to help us conquer this question is Chris Higgins, BRA lead hydrologist.
Thanks for coming back, Chris.
Chris Higgins: Oh yeah, glad to be here.
Charlie L. Shugart: We appreciate it. And joining us for the first time is Don Hood, a hydrologist here at the BRA. Welcome to the pod.
Don Hood: Thanks for having me.
Charlie L. Shugart: Absolutely. So, since this is your first time on the podcast, tell everyone a little bit about your time here with the organization.
Don Hood: Yeah, I've been here just a little shy of a year. Kind of like you alluded to, I did not walk into this job knowing everything about the Brazos Basin and everything that was in it. But what's funny is I remember a person that I now know as Peyton, who's been on the podcast before, he came to Baylor when I worked there and presented on BRA activities, and I attended that presentation, and I thought, “Oh, that's pretty cool,” and didn't think about it again for a few more years after that, and here I am.
Charlie L. Shugart: I love that. It's amazing. Before we get too far into this, can you guys just explain what a hydrologist is? I mean, we know well, some of us know that hydro comes from the Greek word water. That's kind of like as far as my brain takes me.
What do you do as a hydrologist?
Chris Higgins: You want to give it a whack, and then I can tag along.
Don Hood: Sure. Yeah. I mean, yeah, like you said, hydro, water, ology, study of, we study water for our purposes. We are maybe studying is the right word, the wrong word. We're paying attention to the water in the Brazos Basin and mostly keeping track of it. Where is it going? Where is it coming from? And what are we going to do with it?
Chris Higgins: It's like a lot of professions, like a chiropractor. Some chiropractors do acupuncture. Some of them, like, crack your back. Some of them do all this stuff, you know. Engineering's the same way.
All different types of engineering you can get into. Hydrology is the same way. Some people really focus on sustainability and environmental flows, some water quality, you got groundwater, surface water hydrology. There are all different types of aspects of hydrology, so it's a very broad overarching profession. A lot of what we do is water supply management, and flood management of our reservoirs is kind of how the hydrologists here at the BRA function.
We analyze all kinds of hydrologic data that's tied to our reservoirs, you're looking at evap inflows and or, you know, we're looking at forecasting. We work real closely with, you know, the National Weather Service and the West Gulf River Forecast Center and the USGS, the United States Geological Survey, the Army Corps of Engineers, and the hydrologists, you know, at those different agencies, state and federal agencies, in sharing data, gathering data, analyzing data, and every day is different. That's kind of, you know, a broad explanation of, you know, just hydrology.
Charlie L. Shugart: No, I appreciate it. Maybe we could do a future podcast episode talking more about the job itself, you know? Sounds like it would be a good spin-off.
Chris Higgins: Yeah.
Charlie L. Shugart: Okay, so let's move from what you said a little bit about tracking water. You guys track the BRA's water supply usage. But before you tell me how, tell me what makes up that system.
Chris Higgins: So, our BRA water supply system is our 11 water supply reservoirs. Three of them are owned by BRA, the other eight are Army Corps of Engineers that the BRA has water rights and water supply contracts with the Corps to be able to store and use that water for water supply purposes. And we also have East Williamson County pipeline. We have the water treatment system, and then we have the West Central Brazos raw water pipeline that transfers water from Lake Georgetown to Lake Stillhouse Hollow, and that pretty much comprises the BRA system.
Don Hood: Other way … It goes from Stillhouse Hollow to Georgetown.
Chris Higgins: Oh, oh, it goes from Stillhouse Hollow to Lake Georgetown. Sorry. It's all surface water, no groundwater at this point.
Charlie L. Shugart: Talk to me about how you track that. I mean, how do you track water across the basin?
Don Hood: It's tempting to think of it like, yeah, we know how much water is flowing through any part of the basin at any given time, and the truth is that we really don't. We have points in places where we know how much water is flowing, so at all of our dams and at all of the Army Corps' dams, we have a sense of how much water is being released. There are stream gages along the main stem and along all the tributaries, or not all the tributaries, but many of the big tributaries, that give us a measurement of how much is flowing there. But there's a lot of places where we don't know, un-gaged sections where we don't know how much is coming down the river until it passes a point where we can observe it. We're limited in where we're able to track and know exactly what's going on, but we have experience and knowledge that help us fill in the gaps.
And so, if you have a gage here in Waco, another one at Highbank, which is a little downstream, and the next one, if I'm not mistaken, is Bryan, and, you know, six inches of rain falls between Waco and Bryan, we can't see it yet. We know it's coming.
Charlie L. Shugart: Right.
Don Hood: Because we know that the water fell and all that, but we can't just pick a point in the river and know how much is there. It has to get to somewhere where we already have a station observing. So, that's what we're watching in terms of tracking flow, and that's where the information for the accounting plan and knowing what's going in, what's coming out, who's pumping what, etcetera. That's where all that information ultimately comes from.
Chris Higgins: It's a very important part of, like, our job. For instance, our three reservoirs, which are Possum Kingdom, Lake Granbury, Lake Limestone, all the components of that reservoir. So, you got evap, you got water use, you got releases, you have leakage through the dam, you have environmental flow releases. You also have inflows, but inflows are very hard to measure. And so, you have to track all these other components, which are somewhat easier to assess.
Like when someone pulls water out of a reservoir, they report it, and we know that volume.
Charlie L. Shugart: So, when people are pulling water out of the reservoir, and you said, we know how much they're pulling, are they telling you? Like how do you keep kind of track of if somebody's pulling like a bunch of water or somebody's pulling a little water?
Don Hood: So, when it comes to the reservoirs, I guess this is true everywhere, but when people pump water in Texas with the rules of the TCEQ, the Texas Commission on Environmental Quality, if you're pumping water out of a river, you need to have a TCEQ-certified meter. Probably of all the pieces of information we have, water pumped by or diverted by our users is probably the most precise. And it's a pretty small amount in the scale of the whole system, right? And so those are pretty accurate. And so when you look at a reservoir, like Lake Granbury, like whichever one you like, if we know how much is being pumped out, which we don't usually know the day of, it's all kind of calculated in the days after, you know how much came out from pumping, you know how much came out from being released, and then you can start to figure out what came out via evaporation and what may have come in.
Granbury, for example, you have from every little tributary, from everyone's lawn who has lakefront property, and from the main stem of the Brazos coming right down.
Chris Higgins: But we actually measure evap though.
Don Hood: Yes.
Chris Higgins: That's another measured component.
Don Hood: I'm a very technical, data-oriented person. Our way that we measure evap is the best way to do it. It's a little less reliable than compared to the pumping of a meter on a pump.
Charlie L. Shugart: Right.
Don Hood: It's just a matter of data quality and data accuracy because evap's a very difficult thing to measure.
Charlie L. Shugart: How do you measure evaporation?
Chris Higgins: It seems like a daunting task because when you're looking at an 8,000-acre reservoir or a 15,000-acre reservoir and you know you have these little molecules of this thing happening where the water is going from a liquid state to a gaseous state and going up in their atmosphere along the surface of this reservoir - How do you measure how much water is leaving there? You could look at how quickly the surface elevation is or the change in surface elevation over a specific period of time. But the problem with that is you have other things causing that reservoir to drop other than evap, like water use and like releases out of the reservoir. So, if you measure all those components, you can kind of get a good idea of the evap, but the other big component is inflow, and that's a big component. Even though it's kind of more difficult. It's easier to measure releases and water use than it is evap.
But you have to measure evap because, in order to solve for one of those, one of them has to be known. You can't solve for two unknowns. What we do is we use a pan evap. It's a Class A standard. It's about the size of this table.
It's a four-foot-diameter metal pan, and I don't know how high they are, but they're standard. It's a specific measurement. I want to say they're probably maybe a foot and a half, and we have a weather station at each of our three reservoirs, and each of the three reservoirs has a pan evap. What we do is we take a point at a certain point in that pan. Usually, we do like 8:00 to 8:00, so 8 a.m. to 8 a.m. the next day. And we look at the change in elevation of that pan. And then we translate that to lake evap because the pan- unfortunately, the pan is going to have different thermodynamics, and the heat storage is going to be different because it's on land. The pan's going to get hotter, it's going to evap quicker, so we apply a coefficient to it to get as close to an estimate of lake evaporation as we can.
Charlie L. Shugart: That's a really cool way to do that.
Chris Higgins: There are other ways of doing it.
Don Hood: Yeah, a lot of the tools, a lot of the, I say geology in general and hydrology, a lot of the measurement tools we have are startlingly simple. A lot of stream gages, the most reliable, infallible gage we have for lake elevation is a stick. It is a piece of the dam or something that has markings on it. And it can't move because it's just attached to the dam.
Charlie L. Shugart: Yeah.
Don Hood: So, someone goes and looks at that and says, we are at nine ninety-seven point whatever, and we know that that's certainly true because, you know, that piece of concrete or whatever it's attached to hasn't moved in almost a hundred years.
Charlie L. Shugart: I love that. That's amazing.
Don Hood: And so, the pan is like that. It is it's a standard instrument that's widely used, and you just, you can measure how much comes out of it because it's a very controlled object and you have to, it takes some data to develop that association from the pan to the lake, but we have plenty of data and so now that we've built that association, we can just look at the pan and say an inch came out of that, and we can turn to the lake and say, Okay, was, you know, whatever the correlation would be, half an inch, three quarters of an inch, something like that.
Chris Higgins: The way we describe it is the way we do it, it's an empirical method, but like there's all different types of, like the modified Penman and different calculations where you take data like humidity and wind speed and temperature and solar radiation and other data and you plug them into a formula to get a good representation of the evaporation that's coming out the lake.
Charlie L. Shugart: All the factors you just mentioned are those things that affect the evaporation rate?
Don Hood: Generally, humidity and dryness, how sunny it is, the overall temperature, in addition to how much direct sunlight you're getting, and the wind speed. When it's really windy, you're going to see more evaporation.
Charlie L. Shugart: That's interesting.
Don Hood: Yeah. You're refreshing the air that's touching the water surface.
Charlie L. Shugart: Yeah.
Don Hood: So, you can whisk away that humid air and put some nice dry air there to pick up new water.
Charlie L. Shugart: Interesting. Okay.
Chris Higgins: Well, just think about, like, why do you use a blow dryer? Like, how long would it take your hair to dry if you just put heat on it and you weren't blow drying it?
Charlie L. Shugart: Yeah.
Chris Higgins: You'd just have hot, wet hair if you didn't have the fan.
Don Hood: Just a couple of weeks ago, we had a data quality assurance process, so all of the data for evaporation and inflow and all these other things that we track at our reservoirs get manually approved by one of our technical water services people every week. And I was looking over that data, and I saw that at Possum Kingdom, the evaporation rate doubled one day. And I was looking at other weather data in the area, and I thought, the temperature's the same. You know, it's not that we didn't have rain and then no rain, whatever. And I just sent our staff up there a quick message that said, “Hey, just want to check to make sure this is accurate.” And they said, “Yeah, the wind was blowing like 20 miles an hour.” So, same temperature, same solar insulation, same all that. You crank that wind up, and you can see some serious changes in evaporation.
Charlie L. Shugart: That's very interesting.
Chris Higgins: Yep.
Charlie L. Shugart: I have a few more questions about evaporation, but before we keep going down that trail, when you guys are talking about all the water that you track, how much water are we talking about?
Chris Higgins: Yeah. I mean, if you're talking about stored water, it's roughly about 2,000,000 acre-feet combined at all 11 reservoirs.
Don Hood: I did some math on this beforehand because 2,000,000 acre-feet. I mean, a lot of people are not familiar with an acre-foot. It's a very self-explanatory unit.
Charlie L. Shugart: Tell everybody.
Don Hood: It's one acre of land covered in one foot of water. As much as that's a huge amount and hard to comprehend, it is sort of easy to visualize. So, 2,000,000 acre-feet, if anyone listening is from Houston, that is enough to cover the area inside of Beltway 8 in Houston, which is, you know, kind of the quote-unquote city before you get to more suburban parts in six feet of water.
Charlie L. Shugart: Wow.
Don Hood: So, it covers basically the whole city of Houston in six feet of water. That's about 2,000,000 acre-feet. It's a good bit of water.
Charlie L. Shugart: Yeah. It's a good bit of water. So, what you guys are tracking and accounting for customers that are using, and you mentioned that the water that's from the reservoirs, so are we tracking any water that's being taken out of the rivers or tributaries?
Chris Higgins: There's going to be, I guess, two components of people using water downstream. They're either water right holders, or they have a contract with the Brazos River Authority, with us. If you're a water right holder, any water use downstream, you have to coordinate with the watermaster to be able to use that water, to get permission to use that water, and then subsequently to report how much water you used based on what Don was talking about with the meter readings. If you're a BRA customer, it's the same thing except for, that component of water use has to be reported through the Brazos River Authority. So, we're constantly coordinating with our customers up and down the river that have straws up and down, you know, downstream of our reservoirs.
Charlie L. Shugart: What's constantly?
Chris Higgins: Constantly is multiple times a day with multiple customers. Downstream is a little more involved. The reporting is a little bit more involved than our lakeside because what water you use, when you're located along a river, the water that you actually pull from that river impacts the diverter downstream of you and all the diverters downstream of them. So, you have to monitor it a lot closer to make sure that we're operating in accordance with state law, with ‘first in time, first in right,’ the priority doctrine. The reporting is basically weekly for downstream, it's monthly for lakeside.
The other big major difference is we have to know what the estimated diversions over the following week are going to be for downstream diversions.
Don Hood: Yet another episode on water rights. I don't know if there's been one yet, but there's plenty out there.
Charlie L. Shugart: So, every day, the different customers who are on the streams themselves are calling up to the BRA and saying this is how much water I'm using and will project to use the following week?
Chris Higgins: Well, yeah. It's not every day. It's just that we have multiple customers, so we're getting multiple phone calls a day.
Charlie L. Shugart: That makes sense. Yeah.
Don Hood: So, in theory, every week, they are saying, if you're downstream, “This is what I'm going to pump every day next week, and this is everything I pumped in the past seven days.”
Charlie L. Shugart: Okay.
Don Hood: But there are certain customers that have changing needs, and so they are reporting a little more frequently to adjust that prediction and say, “Actually, we're going to tweak that a little bit.” And there are some customers, you know, that put in one, you know, not one DOI (Declaration of Intent) but every week they're just pumping the same amount, they're just cruising there, you know.
Charlie L. Shugart: What would make one customer have larger variations than another?
Chris Higgins: Maybe they're planting corn or some sort of row crop. You know, if it rains then they may not need to divert from the river to irrigate because it got irrigated naturally.
Charlie L. Shugart: Yeah.
Chris Higgins: And so, they may call and say, “Hey. We had this estimate in, but it rained. We want to change that. We're not going to divert for the next two or three days,” or something. The coordination is different every time.
Don Hood: You know, in some cases, the kind of theoretical pipeline from river to whatever they're doing with it is very short. Like irrigation. They're pumping it and putting it right on their crops. But in some cases, customers are refilling reservoirs or refilling their own storage that they’re using a water right or a contract with us to fill that storage. These could be cooling ponds. These could be whatever else. They don't necessarily need to change it every day. They're just going to pump a certain amount for a couple weeks to fill their own reservoir back up or whatever storage they have back up and cut it off. And then they're going to wait a while.
Charlie L. Shugart: Okay. So, when you are saying customers, you mentioned agriculture, and then we mentioned people who live along the lake themselves. What else makes up the customers of the BRA?
Chris Higgins: It's basically lakeside customers and downstream customers.
Don Hood: You know, the four basic categories are municipal, generally cities, irrigation, farmers, but also individuals in watering their lawns and things. We have mining and industrial, and industrial's a pretty broad category, but they are also some very big users of ours are industrial. Power plants are considered industrial. We have a lot of big power plant users, you know, chemical refineries and things like that. They use a good bit of water, and some of it they buy from us.
Chris Higgins: We have the four categories Don just covered. We have downstream and lakeside. We also have what you call short term/long term. We have some users that come in, mining operations are a good example of that, because they may be only operating in one spot for a short period of time and then they move to the next spot.
And so, it's a shorter-term product we sell on a year-to-year basis. We call it our interruptible water supply system. And then we have our longer-term customers.
Charlie L. Shugart: Like a city who's not moving locations.
Don Hood: Yeah.
Charlie L. Shugart: Only providing water there.
Chris Higgins: And they have to have a reliable supply for planning purposes. So, yep.
Charlie L. Shugart: Are there things that happen and you're like, “Okay. Today it's going to be extra difficult in terms of tracking all of this information.”
Don Hood: Hmmm
Chris Higgins: Well, I wouldn't say … I don't know. It's a good question. The difficulties a lot times come into, like, travel times for our downstream customers because if it's dry, we have to make, you know, water supply releases from a particular reservoir. And, again, that's another whole other podcast on how we make all those decisions on which reservoir to release and how much and all that. But we do have to account for travel times and channel losses.
And so, if a customer needs 100 acre-feet or 100 cfs (cubic feet per second), we have to release a little bit extra on top of that to account for the channel losses from the point of release to the point of diversion along the river. And we also have to account for that in the reporting and when they can start diverting. Because if they start diverting before the water supply release gets there, they could be diverting natural run-of-river water that belongs to a senior water right downstream, and they're essentially taking someone else's water. So it's not that it's difficult, it's something that we do frequently that we have to do, but when you're talking about the flow of water, there's so many things that change travel times with, you know, just how wet or dry it is, how wet the channel is.
Charlie L. Shugart: You're going to have to break that down for me. What, how, okay, if a river or tributary is wet versus dry, how does that affect the travel?
Chris Higgins: Well, let's look at bookends because it's easier to analyze things from bookends. Think of if the reservoir channel is completely dry. There's no water in it. You can go down there and ride a four-wheeler and do donuts or whatever. Whatever you want to do.
And then you release water. There are all kinds of holes and crevices, and the bank is thirsty, and the trees are thirsty. When you start releasing water, all that water is going to be absorbed into the bank, filling those holes. It's going to propagate down the river slowly, a lot slower. It's having to satisfy all these natural needs within the channel and then the channel morphology.
Now, let's picture the other bookend. The reservoir is completely full, and it's flowing like crazy. You put water on top of that; it's just going to slide on down. It's not filling holes. The trees are already satisfied.
The bank is saturated. You're not losing any of that water. That water is like on a slide.
Charlie L. Shugart: Yeah.
Don Hood: I mean, I think everyone's experienced this, especially living in Texas. The first rain after a drought just gets sucked right into the ground. None of it even goes down your yard into the street, right? But after three weeks of rain, it barely rains, and suddenly everything's flowing. It's on a different scale, but it's the same problem and the same principle. The ground, the trees, anything else, if it has a gap, a crevice, whatever, it's going to suck up water.
Chris Higgins: And then seasonal too, like, say you're in the wintertime, and the vegetation is dormant, you don't have that component sucking water out of the river. When you're in spring and summer, you have to contend with, you know, the vegetation sucking up more water.
Charlie L. Shugert: Yeah.
Chris Higgins: And then it's hotter and drier in the summer, so you're going to lose more to evap than in the winter. You’ve got shorter days, cooler temperatures, you're going to lose less to evap, less vegetation uptake.
Charlie L. Shugart: This sounds like a very intense amount of math.
Chris Higgins: Well, yeah.
Don Hood: It's not too bad on the math so much as the paying attention to all those things. Just thinking about them. I was going to answer your earlier question with, ‘What makes it difficult or when is it tricky.” Even only having been here, I've been here through almost one solar cycle.
I've been through all seasons now. So far, it seems to me that kind of when spring going to break time and when is summer going to break time are tricky because when it's starting to be February, March, you got people that want to plant their crops, they want to do things, and they're kind of looking at their watch going, “If it doesn't rain this week, we're going to maybe need some water.” And then kind of the other end of the problem, August, September, it's hot. It's probably dry at this point. And people are wondering, “When is it going to start cooling off? When are going to get that first cool front?” And that's when you are sitting there going, we could release some water. You know, there maybe we need to release some water. How long is it going to take to get there? Is it going to rain while it tries to get there? Those are tricky times.
Chris Higgins: Yep.
Charlie L. Shugart: It seems like Mother Nature, for instance, just has a real big impact on kind of what all of that, I mean, looks like in terms of how you guys are tracking information and how much people are using and how much is in the lakes and …
Don Hood: And that's why a lot of it is … there is math. There's plenty of math. But it's an area where there's a lot of value and experience. I would trust a farmer who has worked on the same section of river, with the same weather, the same climate, and everything, for the past thirty years of their life almost as much as I trust a model, because that person has that on-the-ground experience that's really critical for this kind of thing.
Charlie L. Shugart: Yeah. So, we mentioned a whole bunch of the different customers that we have. How many are we talking about?
Don Hood: About 200.
Chris Higgins: It's going to be a little less than that, but, yeah, you can round it up. Yeah. When you add in the interruptible, it's going to be a little over 200.
Don Hood: It gets a little tricky to count because, you know, we have customers that come and go, like you were saying about construction projects. You know, they buy some water in 2023 and then they don't buy water from us again for a couple of years. And some of those, we don't see them as customers necessarily, but we sell to municipalities, and so they have lots of customers that are kind of, they’re not interacting with us necessarily, but by extension, we're giving a lot of water to a lot of different people.
Chris Higgins: I would caveat that and say that there's almost 200, so there's about a 175 or so, give or take, a few long-term customers. The interruptible customer - it's more of a moving goalpost. It changes from year to year, but that number stays pretty consistent from year to year.
Charlie L. Shugart: So, at this point in time, could we get more customers?
Chris Higgins: We don't currently have any additional water to sell. So, the answer is no. Our contractual agreements and our water sale policy does allow for the resell of long-term water. So, we could potentially get a third party that buys water that's essentially a new customer that's buying water through another one of our customers. But no, no new long-term contracts currently until we bring more supplies online, which is in the cards. It's in the future with the Whitney Lake reallocation and the construction of Lake Allen … I mean, Allens Creek Reservoir. I don't know how many times I've almost called Allens Creek Reservoir …
Don Hood: Are we not going to call it Lake Allen Creek?
*laughter*
Charlie L. Shugart: You did, I think, the first time you called it that.
Chris Higgins: Yeah, Lake Allen Henry. Because it used to be one of our reservoirs. BRA had four reservoirs, and we sold it to the city of Lubbock. And so that's why it's always, like, in my mind when I'm talking about Allens Creek.
Charlie L. Shugart: Okay. So, what you're saying essentially is all the water that we have is already allocated, already dedicated to the different customers that you guys have mentioned, the agriculture, the industry, the mining, and the municipal?
Chris Higgins: Yes. Yes. We're fully allocated currently.
Charlie L. Shugart: So, it's not like we're selling water on, like, a day-to-day basis.
Chris Higgins: No. No. Our water salespeople aren’t like, they're not selling computers. It's a different product.
Don Hood: And truth be told, so Chris mentioned the short term, which we also call interruptible water. I think that's an important part of our sales and business because there are people - it fills a certain niche for people who need water, but that is, in some ways, small potatoes compared to the long term. The long-term sales are the bulk of our water supply, and just in terms of volume being sold, and interruptible is a more bite-sized piece for more bite-sized applications.
Charlie L. Shugart: Could you explain to people what gives us the right to sell that water to people?
Chris Higgins: There's a big misconception that the BRA makes out like a bandit when it rains. The amount of water that we have available to sell doesn't change based on whether it's wet or dry.
Charlie L. Shugart: Oh, so if it rains a bunch, we don't just have more water?
Chris Higgins: Yeah, we don't necessarily. Now, maybe the interruptible product, but like Don said, that's kind of smaller potatoes, and it is based on climate, but we can cut those off at any time when it gets dry. And we can explain that, but let's explain how we come to our long-term component of water sales, where that water comes from.
Don Hood: So, the most basic question, who told BRA, here’s some water, go sell it. The state of Texas. And this was done in the, I'm not a historian, in the 20s, when we built some of our earlier, or we're working on building some of the reservoirs, and you know, it's been ongoing since.
Chris Higgins: Well, PK was the first reservoir. And that was the late thirties.
Don Hood: But it was a process to get there and there was the Brazos, what was it called? The Brazos River Improvement District, I think, is what the first name was. I've been trying to read the history books.
But there was a group of people that came together of their own accord to try and improve the Brazos River for purposes of like trade and navigation, and that kind of had some fits and starts and ups and downs, but eventually that group that was commissioned, was given a commission by the State of Texas to improve the Brazos Basin for broad purposes, but that has kind of coalesced into mostly a water supply commission, and so that was a broad commission given to what would become the Brazos River Authority. In pursuit of that, you know, in the past, almost hundred years, we have built three reservoirs. We have acquired access to all the water in many of these Army Corps reservoirs, and ultimately, what gives us the right is that we have water rights from the state of Texas to store water in these reservoirs, to transport that water down the river, to then let people divert wherever they are. As to how, you know, I don't I'm not a water rights lawyer. We were given the commission, then we asked for the water right, and we got it.
Charlie L. Shugart: Yeah.
Chris Higgins: So that’s what gives us the legal ability to divert.
Don Hood: Yeah, the water right is the legal permission.
Chris Higgins: But the hydrologic amount available … just because the state gives us a water right and says, ‘You have the right to use up to this amount every year from this reservoir,” that doesn't necessarily mean that we're going to do that because we need to be comfortable that we can sell that water on a firm yield basis from one year to the next. So, we do hydrologic analysis to see how much water we can actually sell. Now we're not going to sell more than that water right.
That's why what we were talking about earlier in this podcast about tracking water and gathering that information daily on evap and water use and inflow calculations. That's why that's a big component of why all that's very critical and very important to be able to effectively and efficiently manage the Brazos Basin. We have to have that information to be able to put into our models and do a firm yield analysis on our reservoirs to see how much water we can sell given the worst drought on record. So, we look at a long period of hydrology, what we call the drought of record, or you'll hear it called the critical period. There are other names for it. What we're saying is we're going to sell you this water. We're going to give you a contract. We're saying that based on the hydrology, unless there is a drought worse than we've ever seen, this water is firm. We're guaranteeing this much water for this year, and that's what we're comfortable with as an organization, as hydrologists, in selling based on that. So, we sell water based on a firm yield basis.
Charlie L. Shugart: So, the state says, “You have X amount of water.” And then you guys review the historical data of weather and water and determine that figure, and then that water is disseminated to the different customers you guys have mentioned. Did I simplify that enough?
Don Hood: Yeah, and I think it's important to realize that firm yield, which is that magic word that Chris is talking about, it's something that is a calculated number, and it has to do with, of course, you know, the features of the reservoir itself and the hydrologic history that we know of, and there are limitations of that. We don't have climate data going back as far as we would like. We just have it back to whenever we started observing. Right? We don't have it back to the 1200s like we might desire.
But that's a number you have to derive and calculate and come to. And so, it can change. We can do more analysis with new data, with new technologies, with new techniques, and find out that it, you know, has increased or decreased a little bit, you know, whatever. So, this is, it's a dynamic thing. Yeah, we sell what we're comfortable with on that firm yield basis, and all of this is very conservative in terms of making sure that we can supply what we promise to supply.
Charlie L. Shugart: Yeah.
Chris Higgins: Mhmm.
Charlie L. Shugart: Yeah. And so that's why you made the comment about some people think if it rains a bunch, we can sell more. We can't.
Chris Higgins: Yeah.
Charlie L. Shugart: Yeah. Okay. Cool. I think I got. I think I'm there. I think I got it.
So, when you're talking about all that water, how much water are we talking about? Because the number you gave earlier was for the lakes, right?
Chris Higgins: Mmhmm.
Charlie L. Shugart: Okay, so how much water do we have permitted to us?
Chris Higgins: You're on the order of like a million-acre feet, but we don't sell that much because we're not comfortable selling that much.
Charlie L. Shugart: Because at some point in history, there was a really bad drought, and you are revolving the information around that.
Chris Higgins: Yeah, we study it and model it and do the firm yield analysis, and what we have sold right now under contract, the amount of water that we have under contract right now is about 750,000 acre-feet, give or take a few. We're currently not going to sell any more than that. That's kind of where we're sitting.
Charlie L. Shugart: Yeah. The idea is to never get to the point where we can't meet what we said we would provide people.
Chris Higgins: Yeah.
Don Hood: Correct.
Chris Higgins: A lot of customers have water under contract for basically insurance for extreme drought conditions or for future demand growth. It won't be needed, you know, for another decade or two or three or sometime out in the future.
Don Hood: I want to point out, too, that the critical period, the drought of record, whatever you want to call it, you know, it's not some horrific day in the past that has already happened, and it was all this terrible drought one particular year. Every reservoir, as we pay attention to them, has its own drought of record. Now, a lot of them are the same because there are big, terrible droughts. But I believe the drought of 2011 was the drought of record for at least a few reservoirs.
Chris Higgins: Yeah, for our mainstem system.
Don Hood: This isn't ancient history. 2011 was, you know, fifteen years ago. A lot of our operations are poised around every day is the beginning of the next drought of record, and we need to keep operating like that's going to happen.
Charlie L. Shugart: Yeah.
Chris Higgins: Lake Proctor, its drought of record is in the early 2000s. I think Limestone has one that's different, but most of the rest of the reservoirs in the BRA water supply system are still tied to the 1950s drought. When we talk about drought of records or critical periods, you know, they span multiple years. Procter's, I think, you know, two plus years, the 2011 drought for PK, Granbury and Whitney was 2011 to 2015. It actually started at the end of 2010 to about May 2015.
Charlie L. Shugart: It's a long time.
Chris Higgins: What else have you got, Charlie?
Charlie L. Shugart: So, if we looked at a pie chart of these customers, the municipal, agricultural, industry, and mining, what's that look like?
Chris Higgins: Like a pie?
Charlie L. Shugart: Yeah. What would be the largest group? How's that how's that divided?
Don Hood: It's about
Charlie L. Shugart: What did I say?
Chris Higgins: It looks like a pie.
*laughter*
Don Hood: It's about half industrial and half municipal. That’s the bulk of it. That's the pie. There are two big slices, industrial and municipal.
Charlie L. Shugart: Okay.
Don Hood: And you know, both of those are 45%, 48%, something like that. And then, 4%-5% is irrigation, and then just a little bit, 1% or 2% is mining. So, really, that's the breakdown. And it varies year to year. You know, rainy year can have less irrigation, but that's it's usually something like that, plus or minus a couple percent.
Chris Higgins: Yeah. I haven't heard it recently, but there was kind of a misconception among the public that mining operations and these fracking operations were sucking up all of our water. If you look at the total amount of water use allocated to mining use from one year to the next, it's usually, like, .04%. It's just such a small amount of water that's actually being used for these fracking operations. So, it's not draining our lakes. It's almost negligible; it’s such a small amount.
Charlie L. Shugart: I think now is a good time to remind people that the Brazos River Authority does not own all the water in the Brazos River Basin, that there are other people who have their own water rights.
Chris Higgins: Yes. Yeah, there are other substantial water rights other than the BRA. We do have the biggest piece of pie - talking about pie chart. If you put it on a pie chart, the Brazos River Authority is going have the largest amount of water rights.
Charlie L. Shugart: I imagine that's probably tied to the fact that we built three lakes, though.
Chris Higgins: Well, and then we have the water rights to the other eight Corps reservoirs, so yeah.
Don Hood: But Chris mentioned the priority doctrine, the first in …
Chris Higgins: First in time, first in right.
Don Hood: Yeah. So, it's not, you know, we don't get to be the big bad bully of the Brazos Basin. That would be a good, like, team name, though.
*laughter*
Don Hood: We do not have the oldest priority date water right in the basin. There's one in the lower basin from 1926, which precedes any of the ones we have.
Charlie L. Shugart: Wow.
Don Hood: And there are plenty that are younger, or earlier, or later in priority date than us. The priority date puts you in line in a certain order, and we all have to abide by that.
Charlie L. Shugart: Okay. We've taken the long route to get here.
Chris Higgins: *sinking* Take the long road home. Sorry.
Don Hood: You'll get copyright struck if you sing too long a song.
*laughter*
Charlie L. Shugart: Who, where does the largest percentage of the water that we have go?
Chris Higgins: The most losses from water, when you look at everything, all the components of water leaving the basin, what are those components? You got water users, you got evap, and then if you're talking about a specific reservoir, you have releases, leakage. When you look at all the different components of water losses in the water supply system, evap is the number one user.
Charlie L. Shugart: Over everything.
Chris Higgins: Yes. Yep. Well …
Don Hood: So, you said, you said …
Chris Higgins: Evaporation really isn't a user. It's a phenomenon. It's like a natural phenomenon.
Don Hood: It's a “Femininomenon.”
*laugher*
Chris Higgins: *singing* Do be do be do de … Phenomenon.
Don Hood: Now, I will say, because I got asked this question a couple of weeks ago, this is maybe cheating. A lot of water just goes into the Gulf of Mexico. There's a lot of water just flowing past Freeport and going into the Gulf, and it's over a million in most years. Million-acre feet that is. But yeah, in terms of users, you know, if it goes into the Gulf of Mexico, it's gone to us, it doesn't really matter for us. But evaporation is between 400,000 and 500,000 acre-feet per year. And that's the price of storing, having all this water ready because it doesn't just sit there and do nothing. It does sit there and evaporate, so we have to pay rent, kind of, with our water.
Charlie L. Shugart: I think that's an incredible thing that people will hear. I mean, that's …
Chris Higgins: Yeah.
Charlie L. Shugart: … to have that kind of an impact on the system like that is …
Chris Higgins: Yeah. And if you don't believe us, just fill like a five-gallon bucket of water and put it on your front porch, like in the sun preferably, and just go check it out after a couple of days. After a week, you're probably, you know, in a bucket, you're probably going to see it's going to be half a foot low.
Don Hood: Our reservoirs are not I don't have a good mental sense necessarily of the aspect ratio, but they're not particularly deep. I mean, they're deep, but they're also very wide. These are largely dammed up riverbeds. Every reservoir in the basin is a dammed up riverbed.
And so, they are not big, deep holes in the ground like you might be thinking in your head. They're deeper in the middle where it used to just be a flowing river, but they're pretty shallow out towards the edges because that's just flood plain valley and things like that that we've now flooded with reservoir. So, if you think about evaporation, right, you think about pouring, fill a bowl with water and fill a kiddie pool with the same amount of water, that kiddie pool's going to disappear a lot quicker because of the shape, because of how wide and shallow it is. I don't know if that's an appropriately extreme example, but our reservoirs might be closer to kiddie pools than buckets in terms of how deep versus how wide they are. So, they evaporate a good bit.
Charlie L. Shugart: Yeah, no, I mean that makes sense.
Chris Higgins: It does depend on the reservoir. They evaporate at different rates based on the geomorphology of the reservoir itself, like Don was saying, and how deep and shallow it is. Lake Somerville has a large surface area, and it's shallow. It's less efficient when it comes to evaporation. PK is a very deep lake, like almost in a canyon.
It's going to be much more efficient when it comes to evaporation. And the way it stores heat and releases that heat in the form of evaporation, it's much more efficient. So, it changes from one reservoir to the next.
Charlie L. Shugart: So with that number that you're talking about, like, what's that compared to something else? Like, put it in perspective for me. If X amount is lost to evaporation each year …
Chris Higgins: Oh, the total amount of actual customer water use?
Charlie L. Shugart: Yeah.
Chris Higgins: Oh, yeah. The most we've ever used is about 487,000 acre-feet in 2011. Typically, on any given year, it's going to be between 250,000 and 350,000 depending on how wet or dry it is.
Don Hood: Use on your driest year gets close to evaporation on a pretty wet year. I don't know off the top of my head the total evaporation in 2011, but I would bet it was high. Because, you know, when you're in a drought, it's hot and dry, you're going to get more evaporation.
Charie L. Shugart: Yeah.
Chris Higgins: If you've been in a prolonged drought and all of our reservoirs have been low for a long period of time, you're actually going to see less volume evaporated out because you have less surface area.
Don Hood: That's a good point.
Chris Higgins: Picture this. So, if you like, when we get into the dog days of summer, like, basically, we're in now. So, if July was just hot and dry, we would lose probably 14 inches… so a little over a foot of water.
Charlie L. Shugart: 14 inches over a month. 14 inches in one month at PK to evaporation? That's crazy.
Chris Higgins: Yeah. That's not accounting for rainfall that may occur or anything like that. It's just pure evaporation. So, in the dog days of summer, you're looking at a little over a foot a month is what I've seen over the years. Just think if your reservoir is half full, it is kind of like, a lot of times, it's kind of like a funnel. So, the lower it is, the less surface area you get.
So, you may lose the same amount, a foot a month, but that's over less surface area. So, the volume is going to be less. It's just another way to look at it. So, you would think, oh, man. It's so dry, so hot for so long. Why was there less evap? Well, because our reservoirs were lower. So, just a little tidbit of information.
Charlie L. Shugart: Yeah. No. I like it.
Chris Higgins: Yep. Oh, it's manomenon, not phenomena.
Don Hood: The song?
Chris Higgins: Yeah. Do be do be do de … Phenomenon. Yeah. Not phenomena. Manomenon.
*laughter*
Charlie L. Shugart: I thought you did it that way on purpose.
Chris Higgins: Maybe I did.
Charlie L. Shugart: Okay. So, you guys …
Don Hood: This is every day.
Charlie L. Shugart: Okay. So, you guys have this wide range of different numbers that you're tracking, evaporation, use, inflows, releases. Is there anywhere that anyone listening at home could just look at that information?
Chris Higgins: It's all available. We develop a product every year that just basically summarizes the year, and those are all on our website. It's our water use and accounting summary.
Charlie L. Shugart: Okay.
Chriss Higgins: And it has all that information. It has all of our water use data, where it was used, the location of use, who used it, and how much they used, of course. And then you have our reservoir component, and it basically gives all that information that we've kind of talked about, with how much water was released, environmental uses, for water supply uses, leakage, and then the evap component and inflow, the inflow calculation. All of the reservoir data and everything is all summarized in that report that's available online.
Charlie L. Shugart: Yeah. Anyone can take a look at it if you love numbers.
Chris Higgins: Oh, yeah.
Don Hood: There's a lot of numbers.
Charlie L. Shugart: How long have we been putting that together?
Chris Higgins: Since 2014.
Charlie L. Shugart: Okay. Okay. Okay. So, we've several years' worth of cool data out there. Yeah. Did we forget anything you think is important for people to know or that we didn't touch on?
Chris Higgins: But there's really nothing. Did you think of something?
Don Hood: I'll say I'll just say one thing that this was impressive to me when I started to learn what was going on in the basin and the numbers of it all, but I think it's relevant to, maybe more relevant to, you know, the general public of the Brazos Basin is, you know, how big and important our flood releases are and can be because this is the scale that I cannot say that I comprehended. So, I'm looking at one of our summaries right now. So, this is an example of what you can pull off a summary. This is from 2025. And if you look at, I'm going to pick Lake Granbury. In 2025, as we measure it, a little short of 900,000 acre-feet flowed into Lake Granbury. And almost 800,000 was let out as a flood release. So, when we get these serious storms in our basin, 800,000 acre-feet is more than we lost to evaporation, and it's more than we sold to customers in the whole year, and that was off of just the storms and the rains that we had. And so, there's a sort of bonkers scale to all of this, like, we can store 2,000,000 acre-feet in the whole basin, and one year of decent storms, and almost half of that flowed out of Lake Granbury. And so, the scale of that is sort of surprising and impressive, and it's all sorts of things.
Chris Higgins: The other takeaway to that, Don, though, is it goes to show that inflows or rainfall or rainfall runoff into our reservoirs is the biggest driver in reservoir elevation. It's not water use or evap, it's the lack of inflows. So, the evap's always going to happen. The water use is why those reservoirs are there, that's got to happen. Those aren't going to change.
And they're going to fluctuate, you know, depending on the climate for any given year. They're going to fluctuate sub-annually. Half the year may be wet, and then they just turn the faucet off, and then someone just turns the oven all the way up, and the rest of the year is hot. We've had plenty of years like that. It's the tale of two halves and they're going to fluctuate based on that.
They're always going to happen, and they're going to fluctuate to a certain degree. If you don't get the inflows, your reservoirs are going to go down. If you get the inflows, your reservoirs are going to go up. So, the biggest driver by far is rainfall and associated rainfall runoff into our reservoirs.
Charlie L. Shugart: Yeah. Things we don't have any control over.
Chris Higgins: Yeah.
Don Hood: Mmhmm.
Charlie L. Shugart: Well then, Chris, Don, I appreciate you guys coming and answering all of my questions and breaking it down so I can understand and others. I thought this was very helpful.
Chris Higgins: Oh, yeah.
Don Hood: I'm glad.
Chris Higgins: Well, I'm glad we were able to help out. We're here for any other questions, and, yeah, enjoyed it.
Charlie L. Shugart: Alright. For everyone listening, thanks for vibing with us today on Unpacking the Brazos River. Drink some water, stay curious, and don't forget to hit subscribe button on your way out.