How The Western U.S. Could Rebuild Its Water Infrastructure

17:25 minutes

looking out over a parking lot that's partially flooded with plant debris scattered across it with palm trees and buildings in the background. a lone person in reflective weather gear picks up debris
The aftermath of a rainy bomb cyclone in Santa Cruz, CA in January 2023. Credit: Shutterstock

In early January, California was inundated with record-breaking rainfall. The state was battered by back-to-back storms, which caused severe flooding and power outages.

But could there be a silver lining in those storm clouds? Given the historic drought conditions plaguing the western U.S., a way to collect or divert rainwater to use when the dry season hits is especially appealing. However, potential solutions are not within easy reach. 

Ira talks about the limitations and opportunities of storing and diverting rainwater with Dr. Andrew Fisher, hydrogeologist and professor of earth and planetary sciences at the University of California, Santa Cruz. 

Later, Ira is joined by Dr. Sharon Megdal, director of the University of Arizona’s Resources Research Center, to talk about the drivers of the water crisis and some of the policy solutions being floated to solve the problem. 

Segment Guests

Andrew Fisher

Dr. Andrew Fisher is a professor of Earth and Planetary Sciences at the University of California, Santa Cruz in Santa Cruz, California.

Sharon Megdal

Dr. Sharon Megdal is Director of the Water Resources Research Center at the University of Arizona in Tucson, Arizona.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Do you remember back a few weeks ago when California was inundated with record breaking rainfall, the state being battered back to back with storms causing severe flooding and power outages? You know, I kept thinking maybe there’s a silver lining in these storm clouds.

I mean, finding a way to collect or divert the rainwater to use when the dry season hits, especially given the historic drought conditions plaguing the West, well, how tough could that be? I wanted to know. So joining me now to talk about the limitations and opportunities of storing and diverting rainwater is my guest, Dr. Andrew Fisher, a hydrogeologist professor of Earth and Planetary Sciences at UC Santa Cruz based in Santa Cruz, California. Dr. Fisher, welcome to Science Friday.

ANDREW FISHER: Thank you. I’m very happy to be here.

IRA FLATOW: Let’s set some base data here. Start off by giving me a brief California drought up. Have these back-to-back storms in early January replenished the state’s water supply in some meaningful way?

ANDREW FISHER: Not yet. We talk about water in California in the west in terms of water years, and our water year begins October 1st. And that way, a full year encompasses a single rainy season, which, for us, is mostly in the winter and early spring. And we started out with a relatively wet water year this year.

And we got those amazing storms, a number of atmospheric rivers. It was so much water in some cases, it caused flooding and landslides and problems. But then, we haven’t had any rain since then. If we don’t get more rain this season, we’re going to end up with a sort of average to even slightly dry year in many parts of the state.

IRA FLATOW: Well, given just how much rain there was last month, it seemed logical to just collect this rainwater and save it for later. But I guess logic and ease are not on the same page here.

ANDREW FISHER: That’s right. There is quite a bit of effort that is going into collecting water from these big events. And so some of it was collected and stored. The big challenge is where and when and how quickly that water arrived. It’s quite a challenge when you have large flows and streams and rivers and just sheets of water flowing off the land. It’s a challenge to collect that water fast enough and get it to a place where there’s space where you can get it stored for later.

IRA FLATOW: Well, let’s talk about it. You mentioned we could talk about how we could store it. Give us some ABC’s on that.

ANDREW FISHER: Absolutely. Within California and much of the West, there’s really three forms of freshwater storage that I’d say are the most important in terms of the volume of water. Number one is our snow pack. And that’s the seasonal precipitation that falls as snow, mostly at higher elevations. And historically, this is a really important part of water supplies in the West. The snow melts in the spring and summer, and it provides really important flows during those times.

If we look in California, this is one of the biggest forms of storage that we have. And yet what we’re seeing right now and what we see in the climate model predictions is that by 2100, a lot of that snow pack may be gone. The next really important form of storage is water and reservoirs behind dams, and it’s a lot of water.

But most of the good dam sites have been built. In addition, when a reservoir behind a dam fills after a big rain event, we’re not able to hold all of that water because we need to make room in the reservoir for the next storm. So there are very careful rules that dam operators have to apply in order to release water and make space. And if the landscape is already wet and the rivers are already full, then a lot of that released water does just flow out into the ocean ultimately.

And the final primary storage form is groundwater. And as many people have probably heard, there are many aquifers around the state that have been depleted or partly depleted in recent years. Especially during the drought, we rely heavily on groundwater.

And the one silver lining, I think, we could say when we deplete groundwater is, we are making space for more storage. However, it’s a challenge to get this excess water to those places fast enough, get it into the ground quickly enough in the places where there is room, and also pay attention to things like water quality, which is really important when we add water to aquifers.

IRA FLATOW: And is it as simple as directing the water over the area where you think the aquifer is and letting it percolate down? Is that how you basically just recharge it, or is it more complicated than that?

ANDREW FISHER: There’s a number of different methods. And they can range from inundating quite large areas and letting the water find its way. Even if the most recharge is only occurring through a tiny fraction of the landscape, if you’re able to inundate a large enough area, the water will find its way. But that could be problematic in some areas. Not every area has accessible land that could be used like that. And if there are crops being grown, not all crops are tolerant to repeated or extensive inundation.

Another approach is to try to select the areas that are especially suitable– the right soils, the right conditions. There’s an issue of infrastructure. We’ve got to get that water from the place where it’s running off to the place where it can infiltrate. And then we do have to look at the water quality. Even if the water going in and the water in the aquifer are both pretty good, sometimes when you mix waters of different chemistries, you can end up creating problems.

Sometimes there are, say, chemicals on the landscape, maybe pesticides that were used many years ago, maybe fertilizers that are currently being applied, we need to pay attention to that because the water we apply to the landscape can wash those materials into the ground.

IRA FLATOW: Hm. Now when you flood an area to recharge the aquifer, does it stay there in that one spot? I mean, can you paint me a picture of what the aquifer looks like underground and how the water travels through them? Because I’m really geeky. I want to know. This is really getting into the weeds, so to speak.

ANDREW FISHER: Oh, this is such an important question. One of my colleagues, Graham Fogg, who works at UC Davis, I’ve heard him say multiple times, most of the aquifer is not an aquifer. And what he means by that is we think of aquifers in a simple fashion, as just being a layer cake of different materials. As an aside, when I was a little kid, I used to imagine groundwater was like frothing cataracts of rivers that flowed through the ground.

But it’s not. It’s mostly water moving through little cracks and spaces between grains of sand, or cracks in granite or other rocks. And if you think about what an aquifer looks like, imagine the shape of your hand. It’s not necessarily a simple shape like a cylinder or like a shoebox.

It might be this weird amoeboid shape that goes a greater distance in one direction, less in another, and then within the aquifer, there are pathways. There are channels, like the veins and capillaries in your fingers, that might carry 95% of the water. So the rest of the aquifer might be sort of dead space or space where there’s water, but it’s moving very slowly.

IRA FLATOW: What about wastewater? Can that be filtered enough to return to the aquifer and to be drinkable?

ANDREW FISHER: It absolutely can. One of the examples here in California that’s been doing it for quite a long time is in Orange County in Southern California. What they actually do is most of the water that they recycle, in fact, they don’t deliver it directly to customers. They put it into aquifers. And the idea is that the additional time, the additional distance the water travels, the aquifer can provide an additional level of filtering and safety.

But there are challenges. Recycling is relatively energy intensive, like desalinization. The cost of that water compared to, say, collection of water from major rivers or water from storm runoff, it’s quite a bit higher. And there are technological developments that are improving the ease of water purification. But it’s nevertheless, it remains today a relatively expensive approach, and therefore, much more applicable to urban areas because urban water users tend to pay more for their water anyway, compared to, say, agricultural or rural water users.

IRA FLATOW: Given all the caveats that you’ve talked about and all the exciting possibilities, how big of a role do these methods we’ve just discussed to preserve groundwater play in preventing or staving off drought in California?

ANDREW FISHER: In terms of groundwater, it can play a significant role. In some basins, groundwater is the primary water supply. However, when we look statewide, I’d say the groundwater part is maybe a 10% to a 30% solution over time. It’s not going to be the entire solution. So there’s going to need to be a portfolio of solutions. But if we can bring to the table some options for also improving supply, for creating incentives for people to change what they’re doing so that they see a reason to engage and collaborate, that’s how we’re going to solve the problem.

IRA FLATOW: Dr. Fisher, you’ve answered lots of my questions. I want to thank you for taking time to be with us today.

ANDREW FISHER: You’re welcome. It was a pleasure.

IRA FLATOW: Dr. Andrew Fisher, hydrogeologist and professor of Earth and Planetary Sciences, University of California, Santa Cruz, based, of course, in Santa Cruz, California. Let’s continue discussing the role of rainwater collection in shoring up California’s water reserves because despite all that rain, the state’s water future is also largely dependent on cooperation with other states. Southern California gets a lot of its water from the Colorado River.

And so California is part of an agreement with six other states and tribal nations to share this precious resource and just recently California refused to sign on to a proposal to cut back on the amount of water they use. Joining me now to help make sense of what this latest squabble means for the West’s water future and discuss some of the other policy solutions on the table is my guest, Dr. Sharon Megdal, director of the University of Arizona’s Water Resources Research Center in Tucson. Welcome to Science Friday.

SHARON MEGDAL: Thank you so much for having me.

IRA FLATOW: Nice to have you. What are the ramifications if California doesn’t come to an agreement with the six other states– Arizona, Colorado, Nevada, New Mexico, Utah, Wyoming– on cutting back its water usage?

SHARON MEGDAL: The situation out here in the Colorado River basin is really quite complex. And over the years, there has been a history of the states and Mexico and tribal nations working on these issues. But what we’re facing right now is extreme shortage of the Colorado River water flows. And we’re in unprecedented territories in terms of what’s being asked of water users.

We’re talking about big cutbacks. The seven states haven’t come to an agreement. We hope that we can get to an agreement so that the federal government doesn’t impose its solutions on the states. But if the states don’t come to agreement, it is the responsibility of the federal government to figure this out.

IRA FLATOW: Because there’s a lot at stake in that agreement, right, with the amount of water usage.

SHARON MEGDAL: Yes, there’s much at stake here. And the fact of the matter is we’re talking about agriculture, which uses a large portion of the water across the entire basin. And we’re talking, by the way, about water that 40 million people depend upon in some way.

It supports agriculture. It supports communities. It supports industry. It supports the environment. And so when there’s less water to go around, there’s a question of who experiences the cuts and how much. There are solutions, though, Ira. We can spend a lot of time talking about the problems, but we should talk about the solutions.

IRA FLATOW: Yes, let’s get into them. Give me an idea of some of the solutions.

SHARON MEGDAL: All right, so I’ll give you a quick list, but they’re not simple. We can conserve water. We can use less. We can be more efficient in our use. That sometimes can be the low hanging fruit. We’ve done it when we can. We can do more. But that’s not enough to get us to where we need to be.

We can reuse water. We can take very highly treated wastewater and reuse it. We already do for turf irrigation. We can augment our water supplies through sometimes I call it manufactured water, desalinated water, where we take water that otherwise is not usable and make it usable through technology and treatment. We can move water from one place to another. There are places where it’s plentiful and available and not being used.

IRA FLATOW: They’ve been talking about moving water from where you have floods to where you have droughts. Is that feasible to do that?

SHARON MEGDAL: The question of moving water depends upon where you’re taking it from and where you’re moving it to. And one of the options that’s getting a lot of attention these days in discussions is what about taking floodwater from the Mississippi, from the Midwest, and moving it to Southern Arizona or places in the Southwest that are dry? The idea is to come up with something where you don’t have losers. A lot of times, moving water involves losers. You’re taking my water that we need in our area and moving it to somewhere else.

But if you’re taking somebody else’s flood water, that could benefit them, the source of the water, and it could benefit those to where you move it. This is a long-term, very complicated option that not that many years ago, people just rolled their eyes and said, don’t even talk about it. Now it’s getting serious discussion. Arizona and other areas in the West are still growing. We can build in less water use in how we design our buildings, our communities, how much you have lawns and swimming pools. And that, I think, is where there’s a lot of opportunity as we grow, just building less water use.

IRA FLATOW: This is Science Friday from WNYC Studios. These are great ideas, but won’t it take a huge investment of infrastructure funding?

SHARON MEGDAL: Well, the question about who pays and how much is a very important question. Sometimes the challenge is of the decision-making, not the engineering, and it’s not even necessarily the money. It’s the people’s acceptance, people seeing the necessity, the value in undertaking some of these things. But by all means, the question of cost is a very significant one, for example, with desalination, people say, why should we desalinate? It is the most expensive option available, and we should reuse.

What I say to that is we have to have a portfolio, a collection of options. Look at what we can do short-term, medium-term, long-term. And people need to know the facts and need to know that, yes, this will cost more water, but business as usual is not really an option for us.

We can’t use water like we have if we expect to grow, and there’s less water available due to climate change, due to a ridification, it’s sometimes called, due to long-term drought. The river is just not producing as much water. And we have to get into balance with what it’s producing, along with all the other supplies that are available, including groundwater.

IRA FLATOW: Well, you mentioned it’s going to take a combination of solutions. Are you feeling optimistic that we, as you point out, that we are up to the challenge here?

SHARON MEGDAL: I have sometimes been criticized for sounding optimistic. I am optimistic that we can come up with solutions. And I believe we must be optimistic collectively because if we only focus on the problems and are pessimistic, I don’t think we’re going to have the mindset that we need to bring all of the people that it will take, and it will take the engineers and the economists and the water managers and the public to figure this all out.

And if we’re not optimistic that we can come together and come up with solutions, I don’t think we will come up with a pathway forward that the public can agree upon. This is hard work. And this is all-hands-on-deck kind of stuff right now.

IRA FLATOW: Mm-hmm, and we hope they’re all listening because we have been talking about this for years now. Dr. Megdal, thank you for taking time to be with us today.

SHARON MEGDAL: Thank you for having me on the show.

IRA FLATOW: Dr. Sharon Megdal, director of the University of Arizona’s Water Resources Research Center based in Tucson, Arizona.

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