Talkin' Crap

From River to Tap: How Iowa Turns Water into Drinking Water

• Dan Andersen • Episode 24

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This month on Talkin' Crap, Dan Andersen sits down with Christina Murphy, General Manager of West Des Moines Water Works, to discuss how urban drinking water is treated, monitored, and delivered safely to the public.

They also explore the shared challenges faced by both agriculture and water utilities, from nutrient management to water quality pressures, and discuss collaborative steps to improve water quality. 

Dan Andersen:

Hello, and welcome to Talkin' Crap, a podcast by Iowa State University Extension and Outreach. This institution is an equal opportunity provider for the full non discrimination statement or accommodation inquiries, go to www.extension.ia state.edu/legal. In this podcast, we discuss insights into the science, technology and best practices surrounding manure management. Our objectives are to build awareness about the challenges farmers and the broader agricultural industry face around manure and to demonstrate solutions and areas of innovation.

Dan Andersen:

Hello, and welcome back to another episode of Talkin' Crap. This one is From River to Tap: How Iowa Turns Water into Drinking Water. When we talk about drinking water in Iowa, most of the time it's invisible. You turn on the tap, the water is there and you trust it's safe. But every once in a while, something pushes water into the spotlight, and nitrate has been one of those things. Nitrate is not a new issue. It's been part of Iowa's water conversation for decades. What's changed recently isn't that nitrate suddenly appeared, but that weather, water demand, and infrastructure limits have all collided at the same time, high concentrations last summer, elevated nitrate levels again this winter, and more variability in when and how nitrate shows up in the river have made a lot of people ask hard questions about agriculture, drinking water treatment, and who's responsible for what. Today's conversation is not about blame. It's about understanding the system. Because clean drinking water doesn't just happen. It's engineered, it's regulated, and it's planned years, sometimes even decades, in advance. Before we talk about nitrate and treatment capacity, it's important to understand how drinking water actually works, where water comes from, what has to happen to make it safe, and what constraints utilities operate under. That's why I'm really glad to be joined today by Christina Murphy, the general manager of West Des Moines Water Works. Christina brings both an engineering background and on the ground experience running a system that has to deliver safe, reliable drinking water every day. My hope is that by the end of this conversation, we'll have a clearer picture of what's happening, why it's complicated, and how we can think constructively about moving forward together. So Christina, thanks for joining me today, and as we get started, can you walk us a little bit about your water history and how you ended up as the General Manager in West Des Moines.

Christina Murphy:

Yeah. Thanks, Dan, thanks for inviting me to be on this podcast. Little bit about my background, actually grew up at kind of the confluence of the Missouri and Mississippi River. I always tell everybody the reason I spent a lot of time on the water, we were big boaters, so every every weekend was on the water. But at the age of 13, the 1993 flood happened, and so where I lived became an island and had pretty dramatic impact on on people, agricultural obviously, and a lot of communities as well. So I've always had a healthy respect for the power of water, mostly flood situation. So when I went to college at the University of Missouri Columbia, I knew I wanted to do something with water. I just didn't know what it was. So I went in undecided engineering. I wound up getting a degree in biological engineering, which is there the agricultural engineering that we have here at Iowa State, and so with the soil and water emphasis. And so I did a lot with erosion control. And got started in my career, actually with the USDA-NRCS, so I learned a lot about some of the farm programs that are still in existence today, a lot about flood control, erosion control, some actually source water dams or flood protection dams. That's how my career started. And then in like, about 2007 I don't know, there was a position open at the city of Ames as the Assistant Director for both water and wastewater. And certainly I had a lot of experience with source water. I had moved up from the Missouri office to Iowa, so I've been working for the NRCS in Iowa on the PL 566, which was the, you know, watershed protection, flood protection program when it was funded then. And so I just applied. I didn't think I was remotely qualified, but I guess I had a lot of energy so, and I think brought some good skills, a lot of engineers maybe get accused of not having, and so, so I became the assistant director for the city of Ames Water Pollution Control. So in that job, we did both water and wastewater. In the timeframe I worked there, we decided to build a new water treatment plant. And just as we were ready to start design, I followed my husband to a position over at Purdue University, and I stayed home with our kids. And so we had one kid at the time, and had a second while we were in Indiana, I taught a little bit at the university there, and we just decided we really wanted to raise our family back in Iowa, and we loved Ames area, just wanted to be back, and so we moved back. I did some consulting for a while, came back to the city of Ames. I was there for a number more years. Obviously, new plant was constructed, 15 million gallon per day lime softening plant in Ames. And then the position at the West Des Moines Water Works came open, and people asked me. They thought I'd be a good fit. So I took the leap. And so I've been the general manager at West Des Moines Water Works for about six and a half years.

Dan Andersen:

An exciting six and a half years.

Christina Murphy:

It's been a busy six and a half years.

Dan Andersen:

So, I think one of the things since we, generally I have a manure ag audience, what actually happens at a drinking water plant? Like, what is really going on.

Christina Murphy:

Well, you know, so we have to meet safe drinking water standards, and that means there's several 100 contaminants that possibly could be in the water that we need to make sure and ensure that we meet those standards. Every plant's a little different. What really matters is the source for that plant, and then the type of treatment that plant is. So in West Des Moines, and now we're an operator for Central Iowa Water Works, but the plant that we're operating, A.C. Ward, is a lime softening plant. So that's like, approved, like traditional treatment for drinking water. It helps soften water. Really reliable process that's been in place for a number of years. But other treatments, newer treatment technologies, are things like membranes, where they can remove more contaminants. It has a more robustness to us to it, but it costs more to treat drinking water. So I oversee both I help with source, treatment and then transmission. So we got to bring it to the plant, treat it, and then get it actually out to our customers. And so in West Des Moines, we have about 29,000 customers that we serve water to.

Dan Andersen:

Okay, and you said source. So where does the water come from?

Christina Murphy:

Well again, in West Des Moines, the plant there has a combination of both shallow wells and deep wells. However, all of that water for A.C. Ward doesn't supply all of West Des Moines, so we get water from other treatment plants like the Fleur Drive plant and the McMullen plant and and they use surface water. They sometimes have collector wells along the river, but they're under the influence of the water, or they're taking directly from the river.

Dan Andersen:

And then, okay, so it comes in from your wells, or in some cases, from the river at other treatment plants, you have to run some treatment process, you said lime or maybe membrane, but we're removing a lot of contaminants. How do we know the water safe?

Christina Murphy:

Yeah, so we test the water every four hours in West Des Moines and other plants too, they're testing on a very regular frequency. You know, we have a permit. We have to meet those drinking water standards no matter what we do. There's no variance in that. So we control our processes. We control what we can to make sure and ensure we deliver safe drinking water.

Dan Andersen:

So that's one of the reasons there's such a good record at most of these plants. They're testing what's coming in, and then what you're actually supplying to the companies every four hours, apparently.

Christina Murphy:

Yeah, around the clock, 24/7 365, we have an operator. There's operators on staff at the facilities at West Des Moines and I know Des Moines that are testing the water. And so yes, we have to meet those drinking water standards. It's really important that we may have to adjust the process so we need somebody to monitor that. Groundwater sources tend to be fairly stable, but when you use surface water, it can be very dynamic, and you have to stay on top of that. You know, as we get rainfall, things of that nature, that is what we need to do in order to stay on top of the treating, treating the drinking water.

Dan Andersen:

Okay, so you're using a lime conditioning. What sort of contaminant or what are you really trying to treat for in your process?

Christina Murphy:

Well, lots of things. Okay, so you know, the big culprits we see is iron and manganese, and then we soften water, so we're trying to get out calcium and magnesium hardness. Again, every source is different. In the Jordan, which is that deep aquifer that's about 2500 feet in central Iowa, sometimes you can see arsenic or radium. In our shallow wells in West Des Moines, we're we have challenges with PFAs. And if you're a surface water plant, obviously you have challenges with nitrate.

Dan Andersen:

And then surface water plants would occasionally have maybe challenges with E coli or other pathogens.

Christina Murphy:

Yes, so definitely, you're always treating, we're chlorinating. We're treating for pathogen. We definitely want to disinfect. That's just part of the treatment process, no matter what plant you're at.

Dan Andersen:

Okay. Now, as you mentioned, the big deal is probably nitrate, and your plant doesn't specifically have to deal with a large nitrate swings, but in terms of the overall water supply to Des Moines, and since you're purchasing water from a conglomerate, that is a issue you have to face and deal with.

Christina Murphy:

Yeah. So for those of you that don't don't know that at the start of the year of 2025 Central Iowa Water Works became an active entity, when there's 12 members West Des Moines, part of that, and we operate a number of plants in the metro that have to deal with nitrates and so.

Dan Andersen:

So why did, why did all the plants join together? Like, what's sort of the philosophy behind how to supply water to Des Moines?

Christina Murphy:

Yeah. So, I mean, the main goal of CIWW is to provide redundancy and resiliency. So we have a network of core transmission mains and multiple plants that we can push water to different parts of the metro. We don't have an issue with nitrate in West Des Moines, but when we were having nitrate issues, we ramped up production to try and push out as much water as possible through our plant to reduce the burden on the plants that were struggling.

Dan Andersen:

So it's just a way to work together to help with water supply, and maybe when water quality is better at one spot than others, trying to rent

Christina Murphy:

Yeah. I mean, it's a way to work together, and instead of against each other, it's to provide redundancy and resiliency. It's to come together for planning, for for future water needs in the metro.

Dan Andersen:

So the Des Moines Water Treatment Plant was built in the 90s for nitrate removal, so it's aged quite a bit. How is this maybe pushing us towards the future, as you think about what we need moving forward, as Des Moines continues to expand?

Christina Murphy:

Yeah. So we we have like 130 million gallons of day capacity currently in the metro. The Fleur Drive plants been around a long time, 100 years, right? And so the nitrate removal system, I think, was added in the early 90s. It treats about 10 million gallons per day. But the Fleur Drive plant treats 75 million gallons today. So you you're sort of side treating the nitrates as you need to and blending that back in to keep it below the safe drinking water standard. So I talked about lime softening. So in Des Moines, we have Fleur Drive, which is lime softening. McMullen is lime softening. And our plant, so you're talking about 110 ish million gallons per day of that 130 that's using lime softening. Well, lime softening alone doesn't treat nitrate to the level that we need to. So that's why Fleur Drive has site treatment. And McMullen plant actually uses other ponds to dilute the nitrate to get it below 10 milligrams per liter.

Dan Andersen:

So they're going to use their ponds as storage when concentrations are low, put in low nitrate water and be able to blend back.

Christina Murphy:

Yeah, that's the plan. But right now, unfortunately, we have elevated nitrates in the winter, so it's hard to fill back those ponds to get prepared for what you need to in the spring. So there's a lot of operational considerations that people don't really realize that make high nitrate now, year round, right now, anyways, very challenging, because things that you can try and prepare for for summer are not able to happen right now because of high nitrates.

Dan Andersen:

Okay, that's a really interesting one. So traditionally, this would be the time you're refilling your reserves, sort of building supply for higher peak demand in summer.

Christina Murphy:

Yeah. So both in those ponds and then we have something called aquifer storage and recovery wells. Those are very deep wells that we put treated water in the winter time down underneath the ground, about 2500 feet. We call it a big kind of imaginary bubble down there. And then in the summertime, we pull that back up. And in the summer, we were running those aquifer storage and recovery wells to the max amount, again, to try and alleviate pressure, but right now with high nitrate, and then we're also wintertime is a big time when water plants have to do maintenance, and so you're struggling to fill those things that you need for summer reserves.

Dan Andersen:

So it's shaping up to be a challenging year. Just because you're starting behind the eight ball, there's not an ability to build up that water capacity, maybe, like you normally would.

Christina Murphy:

Yeah, we're having to be a little more creative this winter to try and adequately prepare for what we might see next summer. I think, you know, we're a little unsure. We're gonna How long are we gonna continue to see high nitrate in the river? Are we eventually going to flush out what's been stored up in the profile or not? We don't have good tools for the water utility to know what the nitrate levels are going to be. That's challenge for us. And sort of you know what's going to happen. We can look at historical data and make some assumptions about what we'll see.

Dan Andersen:

Yeah, and I think right now, it looks a lot like 2015 maybe coming out of the drought of 2012, but we're sort of saying, Did history change? Did ag practices across the landscape change? How different was the weather? What does that mean for how similar or different it might be?

Christina Murphy:

Yeah, that's exactly the case. And you know, we can see a little bit up on the watershed what the numbers are, and kind of get a feel for what we expect to see in the areas that we're going to withdraw and kind of make adjustments accordingly. Right now, we're okay. Our demand is down. It's not peak demand time. So that helps, but it gets it's a challenging process. It's good for everybody to realize that, you know, the water professionals, we're up a lot at night, looking at spreadsheets, looking at things, making sure that we stay ahead of the game.

Dan Andersen:

And I know I have some water quality plots at Nashua. We measure tile drainage with different agricultural practices. And this year, my water nitrate concentrations that made it to the tile were substantially lower than they were the year before. So we were up around 40 milligrams per liter and what we had cropped in 2024, and then this last year, we were about 15, so substantially lower. So there's hope. But then the question is, really, how long does it take for that water to flush down, not just what went into the tile, but what the tile missed and slowly moves there?

Christina Murphy:

Yeah, it's not like we, you know, we built the nitrate removal system. We've added ponds to McMullen to try and provide, you know, areas of relief. And then we're growing capacity. We have an aquifer storage recovery well coming online this coming year for West Des Moines. So there are tools in our toolbox that are growing, but those take time and so and the reality is, we have to meet the 10 milligrams per liter, and the only way we could do that the summer was by implementing the irrigation ban.

Dan Andersen:

So you'll think about water conservation as you need to to move forward, but right now, it's really figuring out what you figuring out what you can do to have as maximum capacity as you can

Christina Murphy:

Yeah, wintertime is our time to plan for the next season. Get our get our tools in our toolbox ready.

Dan Andersen:

All right. And I mean, now we take the tough part of this conversation. The nitrate concentration is really intense right now for lots of reasons. You had huge demand last year for both water and for nitrate removal with really high nitrogen and I think we hear a lot of stories that ag is making some changes, maybe not as quickly as we'd hope or like, but the reality is, we have a third of our population, really, in the Des Moines metro area for the state of Iowa, and you have to meet that nitrogen water quality standard every day of the year.

Christina Murphy:

Yeah, it doesn't matter what's going on. We have to meet the finished drinking water standard. You know, we talk about, it's, it's a very finite limit that we have to meet on a daily basis no matter what's going on with our source water. And so, like I said, we have these tools in the toolbox that we have in place. We're, we're getting more tools in the toolbox by expanding capacity with that advanced membrane technology, we're looking at expanding the nitrate removal system. It's funny though, because people feel like, well, why don't you just use a different source than the rivers? Like, why don't you just go drill some wells? Well, that's what

Dan Andersen:

I hear a lot from farmers. As I've been out this year, why are they using surface water at all? Why don't we just drill wells?

Christina Murphy:

Yeah, I say this all the time. You can't just go pluck source water out of anywhere, okay. You know, we have to use what's available to us. I think we had calculated in order to replace the demand that we're seeing, I think it's something like 120 some odd wells of large diameter, and they cost a lot of money just to go drill those wells, and so because of the volume of water that we treat, that's why we use surface water.

Dan Andersen:

That's true for most big cities, generally, right?

Christina Murphy:

Oh yes, yes, absolutely, most big cities are using direct withdrawal. We have a lot of cities that are on the Mississippi and Missouri River that are pulling straight from the river too. People are like, we have access to the Raccoon and the Des Moines River watershed. The Des Moines is a larger watershed, and so we can't just exclusively use the Raccoon. We flip sometimes back and forth with the with Fleur Drive. They can flip back and forth based on what we see in those rivers. But this summer, they're all high and so that's what gets really challenging.

Dan Andersen:

Okay. And then one of the things we often hear is shared responsibility for water. And I think oftentimes agriculture feels like they are bearing a brunt of the burden, and in some ways they are. But when we look at land use in Iowa, and nitrate loss is generally related to land use, it's a dominant land use. But as we think about maybe that shared responsibility piece, how has Des Moines, or drinking water, started to work with farmers or water quality in general?

Christina Murphy:

Yeah, I think certainly for West Des Moines Water Works and for Central Iowa Water Works, and Des Moines Water Works too, you know, we recognize that this is we got to work together here. It's not there's not a one size or one person needs to handle solving the problem, and that we have to all work together. It does mean that we're going to have to try and do things, some things different, up in the watershed. Try and get more precision agricultural type tools, where we're only using the nitrogen that we needed, the edge of field practices. We've made good progress, but we have a long ways to go to see the kind of changes that we want. That doesn't mean that we shouldn't be doing things too. So things that we're doing is we're we're building infrastructure. We have a, we have a plan to build $1.2 billion worth of infrastructure over the next 20, 30, years. But that goes right back to our customers and rates, and you're trying to keep things affordable too. We want to make sure people can afford their bills, and we recognize that there's a lot of challenges. Farmers are also trying to do the same thing. They're trying to get maximum yields

Dan Andersen:

Tight economic times like this. It's right. They're trying to stay in business.

Christina Murphy:

Yeah. And I appreciate the conversation, because I think part of this is just, we've been spending time trying to learn what the challenges are with agricultural practices, or what that means the farmer, why do we see nitrate? What's what's going on there? I think there's been a lot of trying to education, trying to happen, and we're trying to do the same. We're trying to bring people into the plants. Talk about the challenges that we have associated with treating drinking water.

Dan Andersen:

Yeah. And I think that time scale is always important. On this you mentioned sort of you're thinking 20, 30 years out, as you build infrastructure, both starting now and continuing the future as Des Moines expands. In agriculture, when we look at this scale, we can't flip a switch and be there tomorrow either. So we all need to make steps. You can't suddenly say, Well, we have enough nitrate removal capacity no matter what comes at us. So it's working together and figuring out how to keep that water safe.

Christina Murphy:

Yeah, and I always tell people, it's really important to remember that, so if I take nitrate out or any pollutant, right, anything that's in my source water, it doesn't go away. Okay, I have to then handle that residual, whether it's nitrate, whether you know, are you discharging it back to the river? And guess what? There are other drinking water facilities downstream from us, and we see impacts, obviously, at the Gulf. Or is it treated at the wastewater plants with sophisticated technology? I mean, they're undergoing a massive expansion to treat nitrate, because they can't discharge it either. And so whatever it costs for us to take out, there's a cost for treating it too. And so it hits more than just drinking water treatment.

Dan Andersen:

Yeah. And I think, I think one of the things I've heard for a long time is, does Des Moines just discharge the nitrate that they remove? And I believe it all it's treated through the wastewater treatment plant.

Christina Murphy:

So at the Fleur Drive plant, the nitrate removal system goes to the WRA and the WRA treats it. Part of the challenge of expanding the nitrate removal facility is currently the WRA facility can't handle additional nitrate loading, particularly the type of treatment. It's a chloride, that chloride, high level chloride, can be problematic discharging back into the river. And so it's kind of a vicious circle a little bit. We're exploring other technology that may be able to be easier for the WRA to receive that waste. And I say WRA, the Water Reclamation Authority, that's sent the regional wastewater facility in the Des Moines metro that almost everybody goes to. So there's always a waste product that you have to manage as well. You know that too. Yeah, talk about manure.

Dan Andersen:

That's right on the manure side. It's the same way. We don't like to think of it as a waste on this show, we think of it as a resource, but certainly every decision you make changes how you're dealing with it, how you're managing it, whether it's an air quality concern or water quality concern, there's trade offs in every decision.

Christina Murphy:

Yeah, well, we use lime softening, and lime softening is used as a soil amendment on agricultural fields, so there's great ways to repurpose it. Nitrate, in this case, they're going to be removing the nitrate, likely, and they they can pelletize it and sell it as fertilizer, as again, great, as long as we're applying it the way, you know, in a way that's helpful to to the soil into the plants.

Dan Andersen:

And that's going to be an interesting and expensive technology to make it solid enough to transport back, but you have to really concentrate it to make it transportable back to a farm.

Christina Murphy:

Yep,

Dan Andersen:

And that's a problem we know all too well on the manure side, trying to think about the economics of moving it further and how we get technology that really upscales it?

Christina Murphy:

Well, I always tell you I remember that because remember on wastewater, we deal with biosolids application so very familiar with distance and challenges with going further away.

Dan Andersen:

Yeah, those are the same types of problems, except manure is a little easier, because water conservation is a little little easier on a farm than maybe for humans, where we use a lot of water. So I really did want to thank you for your time. I think I've learned a lot about what actually happens at our drinking water facilities in central Iowa, but I wanted to give you the chance for the last word.

Christina Murphy:

Well, I think Dan, first step is we have to spend time understanding what the challenges each other have and trying to find common resolution. That's how Central Iowa Water Works happened. We sat down and tried to figure out, what do we have in common? You know, we have a common goal. I think all of us share a common goal, to have good water quality here in Iowa. We all have a common goal, wanting to help each other be successful and just we have to figure out the path on what does that look like? For me, it's not a not one entity has to do this, or we as a water utility have to do that. It's all of us that are going to have to work together to solve this, this challenge, I think it's going to be more dedicated funding towards water quality practices. Would really like to see that ramp up to a level that we think could could make an impact.

Dan Andersen:

At an implementation, speed that we can actually detect at a watershed scale.

Christina Murphy:

Yeah, absolutely. I think we got to look at crop diversification. I mean, what I hear from you guys is that that corn bean rotation, we see a baseline nitrate level in the profile that makes it already a little challenging. So could we do something with diversification, create some better markets for some different types of crops? I think that's possibility. I think. People have referenced the Albert Lea,

Dan Andersen:

The oat facilities and trying, yeah, trying to get something that's always growing. How do we think about rotations that keep Iowa green and hold more nitrogen in the profile?

Christina Murphy:

Yeah, and what I want to say is, we're doing that. We're looking at what we can do too. Can we expand nitrate removal? Can we build more facilities with more more robustness and try and expedite that timeline. Could we continue education with our property owners about fertilization or about reduced irrigation, all those things we're committed to doing that so.

Dan Andersen:

It really is going to take all of us. This is a monumental challenge, but one that I think, I firmly believe, Iowa can continue to farm successfully, looking at new ways, new innovations, precision or diversification, and have clean drinking water for all.

Christina Murphy:

I think it can happen.

Dan Andersen:

Yeah. So with that hopeful message, I really appreciate your time today, Christina, and this is Dan Andersen signing off from a job that sometimes smells but never stinks. Keep on talking crap. Thank you for joining this installment of Talkin' Crap. Be sure to take a look at the show notes on our website for links and materials mentioned in the episode. For more information, or to get in touch, go to our website, www.extension.iastate.edu/immag/. If you found what you heard today useful, or it made you think, we hope you subscribe to the show on your podcast app of choice, signing off from a job that sometimes smells but never stinks. Keep on talking crap.