When the ball dropped on New Year’s Eve, nitrate in the Raccoon River was once again above the drinking water standard, closing out a bad year for water quality in Iowa. Below, I’ve compared this year’s nitrate levels to long-term averages at sites in Iowa DNR’s Ambient Stream Network with at least 20 years of data to get a sense for where and when nitrate was highest and what was unusual about 2025.
To understand these patterns, it’s important to remember that 2025 was not a uniformly wet year. Heavy rains in July broke or came near to breaking some records and caused flash flooding in many communities. These rains also raised the water table enough to keep drainage tiles flowing into into the fall. However, most of the state received less than average rainfall from January through May and from August through December. In a band from Ames to Charles City, that works out to a much wetter year than normal. In other parts of the state, like Dubuque, Ottumwa, and Red Oak, that works out to a much drier year than normal.
Nitrate was much higher than normal in the Boone River, Skunk River, and many others in northern and central Iowa, especially in July and August. Nitrate was within 1 mg/L of the long-term average for the Nishnabotna and other rivers in southern Iowa and for the Rock and Floyd Rivers in northwest Iowa. In the table below, red indicates nitrate was higher than average, blue is lower than average, and white is close to the long-term average.
There are some unusually high readings (25 mg/L in the South Skunk River in January) and unusually low readings (3.3 mg/L at Beaver Creek In July) that may have been collected during a storm or other event that is not representative. This is a limitation of monthly grab samples and one reason why maintaining Iowa’s network of real-time nitrate sensors is important. The Ioway Creek sensor was removed at the end of 2024, but the pattern I documented here here (a quick flush of low nitrate surface runoff followed by a gradual release of high nitrate drainage water) happened over and over, in many places in 2025. These kinds of leaks can be avoided with changes in cropping systems and land use, reduced with better nutrient management and cover crops, or intercepted and treated with saturated buffers and wetlands, but we’ll need a lot more of them to prevent another bad year like 2025.
Our grant from the Water Foundation gave me an excuse to dive deep into a big statewide dataset collected by the Iowa DNR. I presented some of that analysis (along with general tips for data analysis) at the Iowa Water Summit in October. Since my slides rarely make sense without the narration, I have also written up a series of set of three case studies about trend monitoring.
I started learning R, a computer programming language for data science and statistics, in 2020. There was a steep learning curve, but now I get to coast downhill. If I can make an interactive map to display which chloride and phosphate readings from a volunteer event fall into the “good” category, I can reuse a lot of that code to make another interactive map that shows which lakes meet the recreation standard for E. coli. If I can figure out how to overlay maps of watersheds and animal feeding operations to calculate livestock density for 60 monitoring sites, it’s not hard to adapt that to calculate a similar metric for wastewater treatment plants. If I can make a good graph for one site, it’s not hard to scale that up to 50 sites.
Behold! My finest graph yet! On a single page, you can see 20 years of monthly nitrate data for the 48 sites in Iowa’s Ambient Stream Monitoring network with the longest record. The dots are color-coded to show streamflow at the nearest gage on the day the water samples were collected, yellow when water levels were at their lowest and grading to purple when water levels were at their highest. The black line is a 3-year moving average (or at least a close approximation with LOESS). You’ll notice that nitrate levels in most streams shot up sometime around 2014 and have been declining since. But how much of that is a precipitation-related trend tied to the El Niño-Southern Oscillation and how much is due to conservation efforts in the watershed?
Here comes the magic trick! Watch closely, for when I place into my hat all those samples collected when streamflow was lower than average (yellow and green dots) some of these apparent nitrate trends will…. disappear!
Darn it, that didn’t work at all! For the third of three case studies I’ll link to below, I take a closer look at two of these sites: Black Hawk Creek, where I’d expect a moderate improvement based on cover crop acreage and the East Fork of the Des Moines River, where I’d expect very little improvement. The East Fork actually has a much bigger nitrate trend than Black Hawk Creek and I can’t account for it. Maybe I should give up and leave trend monitoring to the experts at Iowa State University and Iowa DNR, they seem to know what they’re doing (see Danalatos et al. 2022).
However, the trick did work when I compared a watershed impacted by mostly point sources of pollution (i.e. sewage treatment plants) to a watershed impacted by mostly non-point source pollution (i.e. agricultural runoff). This is the first of the three case studies. Phosphorus concentrations have increased in the North Raccoon River and decreased in the South Raccoon has decreased, but that’s entirely due to recent drought. The second case study introduces a new metric for identifying rivers that a strongly influenced by point source pollution, and how to track improvement.
The Iowa Water Summit on October 8 brought together 65 people with an interest in water monitoring for a day of learning and networking. The event was one outcome of the grant from the Water Foundation that Prairie Rivers of Iowa was awarded last year and the regular meetings we’ve been having with seven partner organizations. The Des Moines Chapter of the Izaak Walton League made their facilities available and Heather Wilson (Midwest Save Our Streams Coordinator for the Ikes) did the lion’s share of the planning. Thanks to our presenters, to Bud Hartley for taking these photos, and everyone who helped make the event possible!
Planning events, dipping test strips, identifying and counting benthic macroinvertebrates, shocking fish, incubating bacterial plates, calibrating equipment, maintaining databases, analyzing data, communicating with the public… There’s a lot of work that goes into finding out what’s in our lakes, rivers, and streams! Between the Water Summit and my 8 years (!) working for Prairie Rivers of Iowa, I’m starting to assemble a picture of the organizations that do water monitoring and where to find the data they collect. Even so, this will not be a complete list! Feel free to add some more in the comments!
State and federal agencies
State and federal environmental agencies do a lot of water monitoring and have a lot of expertise, so if you’re looking for data, your first stop should be one of these databases.
BioNet houses fish and macroinvertebrate surveys collected by the Iowa Department of Natural Resources and the State Hygienic Lab. If you want to know which streams support stoneflies or whether biological diversity has declined in a certain creek, this is the place to find out.
How’s My Waterway is a convenient way to access data submitted to the Environmental Protection Agency from both state and local partners. For example, IDNR uploads their data once a year, while Polk County Conservation uploads their data once a month. EPA’s old system was called STORET, but now it’s the Water Quality Portal for downloads and the Water Quality Exchange for uploads.
The National Water Dashboard provides access to the US Geologic Survey’s network of stream gages, essential information if you live on a floodplain, if you’re planning a canoe trip, or if you need some context to make sense of your water quality data. The USGS also does quite a bit of water quality monitoring, in partnership with the EPA—the National Rivers and Streams Assessment is the best water quality study you’ve never heard of.
Volunteer programs
Iowa has too many waterways for the agencies to monitor on a regular basis, so if you want to know about water quality in your local creek, you may have to do it yourself. Fortunately, since the end of the IOWATER program, other organizations have stepped up to provide volunteers with equipment, training, and a place to store the data.
Polk County Conservation has a very impressive monitoring program, based on the IOWATER protocols, with data housed on the EPA’s Water Quality Portal. Staff, partners and public volunteers monitor 70 sites twice a month. Partners include Des Moines Water Works, the Cities of Altoona, Ankeny, Des Moines, and West Des Moines along with Des Moines Parks and Recreations and West Des Moines Parks and Recreation.
Partners of Scott County Watersheds is one of several organizations with a watershed or regional focus that organize big volunteer monitoring events (snapshots) two or three times a year. They have created their own database and online dashboard to view the results.
Trout Unlimited has been encouraging anglers in the driftless area to monitor water quality with a test strip and mobile app.
Watershed Projects and Agriculture
Prairie Rivers of Iowa originally got involved in water monitoring to educate the public about the Ioway Creek watershed and track conservation efforts in that watershed. Many watershed projects incorporate water monitoring for one or both of those reasons. A typical approach is to collect water samples once or twice a month during the growing season (plus some samples after heavy rains) and send them to a certified lab for analysis. In our case, that’s a lab operated by the City of Ames water and pollution control department, but others watershed projects have partnered with a university or commercial lab.
Have you seen “Moved by Waters?” The documentary by Fourth Wall Films showcases the conservation, education, and citizen science work that Partners of Scott County Watersheds is doing in the Quad Cities and surrounding farmland. In addition to snapshot events they have a long history of research to try to track down sources of bacteria. Our grant helped them do one more round of microbial source tracking; Vice-Chair Steve Gustafson shared preliminary findings at the Water Summit but it wasn’t straightforward!
The Iowa Soybean Association has supported nutrient sampling of streams and drainage tiles for some 19 watershed projects around the state. The Lower Skunk River WQI project is a good example of that—Pathfinders RC&D collects water samples that are sent to the Iowa Soybean Association for laboratory analysis. Several soil and water conservation districts and agribusiness groups are also partners on the project. Since the ISA collects many field edge samples that come with some privacy concerns, they don’t have a publicly accessible database. However…
Agriculture’s Clean Water Alliance has worked with ISA to monitor nitrate in the Raccoon River, Boone River, and Beaver Creek watersheds. They post annual reports going back decades.
Northeast Iowa RC&D has been coordinating water quality monitoring in the driftless area for 25 years, as described in this article. They have created a nice data dashboard for the Upper Iowa River watershed and the Upper Wapsipinicon River watershed.
Colleges and Universities
The Iowa Water Quality Information System is an amazing map that shows you real-time data from a network of nitrate sensors operated by IIHR (Hydroscience and Engineering at the University of Iowa) and the USGS.
Marty St. Clair (formerly of Coe College, now at University of Iowa) and his students have done sampling and laboratory analysis to support the Middle Cedar River, Indian Creek, Upper Iowa, Turkey River, Maquoketa River, and Upper Wapsipinicon River Watershed Management Authorities.
Drake University’s environmental science department has done stream monitoring to support watershed projects and water recreation in Polk County. It’s often a challenge to maintain access to data that’s collected for student projects, but a solution is in the works.
Iowa State University researchers have done a lot of the field scale and edge-of-field monitoring that established the effectiveness of conservation practices including riparian buffers, saturated buffers, bioreactors, and CREP wetlands. ISU is also responsible for tracking various progress indicators for the Iowa Nutrient Reduction Strategy, including compiling water quality data from IIHR, DNR, and USGS.
Closing Thoughts
Finally, there are organizations that don’t collect data themselves, but help make the other data more accessible to the public. The Iowa Environmental Council sends out a Weekly Water Watch newsletter to provide updates on beach monitoring by Iowa DNR, and they’ve been advocating for standardized, easily accessible, user-friendly data.
That’s an idea I support, and there are people working toward an “Internet of Water.” However, I am a bit skeptical when I hear people say “why don’t you use AI” or “you should really get all this data in one place.” Have you ever tried downloading data from the EPA’s Water Quality Portal that was sourced from more than one organization? I have, and I eventually got something useful out of it, but first I had to delete 20 unused columns and then I had to shorten the column names and then I had to clean up the non-numeric entries that one organization had put in a numeric field, and then I had to filter out the sites where monitoring too sporadic to be representative. Bigger, more flexible systems have their drawbacks.
I am more excited about building relationships and improving communication among the various people who care about water quality and who are involved in monitoring, so we can learn from each other and avoid duplication of effort. Hopefully, the Iowa Water Summit and this article are a step in that direction!
Our 2023 Annual Report is now available with results of both volunteer and lab testing of water quality in lakes and streams in Story County. The 56-page report can be navigating by clicking on headings in the table of contents or by using the “Bookmarks” feature in your PDF reader. Below are some of the key findings.
The volunteer program continues to grow and improve in consistency.
49 volunteers entered 969 data sheets into the Clean Water Hub this season.
Many volunteers are monitoring their assigned site biweekly, with 20 sites sampled at least 20 times.
This was a challenging year for fish and aquatic insects.
In addition to many creeks drying up, volunteers observed dissolved oxygen drop to low levels at 53% of stream sites.
Biological surveys showed mixed results, with some streams scoring poorly but sensitive insects like mayflies present in others.
E. coli bacteria levels in streams remained high.
All thirteen streams with enough data to evaluate this season exceeded the primary contact recreation standard. Three streams exceeded the secondary contact recreation standard: (West Indian Creek, College Creek, and Ballard Creek.
However, over the last four years, most sites on the South Skunk River meet the standard when there is enough water to float a canoe.
Wastewater treatment plants are not yet capable of removing some of the pollutants we monitor, and can have a large influence during drought when effluent is less diluted.
Effluent from the old sewage treatment plant in Nevada was found to be a major source of E. coli bacteria. The new plant, currently under construction, includes a disinfection system that should address the problem.
Stream sites downstream of sewage treatment plants tend to have elevated chloride and phosphate.
The encouraging trends we noted in the 2022 report held up with another year of data. Water quality trends are often driven by weather, but we pulled out subsets based on streamflow to remove some of this influence.
E. coli in the South Skunk River below the Ames Water Pollution Control Facility has improved relative to the pre-2014 baseline period, especially during dry conditions when wastewater has the greatest influence.
Nitrate in the South Skunk River below the confluence with Ioway Creek improved relative to the pre-2014 baseline period, even after excluding dry periods. This pattern is consistent with improvement from conservation practices.
On Tuesday, March 12, residents on the north edge of Ames noticed that the South Skunk River was cloudy and had turned an unusual shade of bluish green. By the time I looked at it on the afternoon of March 13, the color had faded and the water was less cloudy, but it still had a soupy, streaked appearance that I’ve seen before in lakes following a toxic algae bloom. I’m gonna go out on a limb here and say it’s blue-green algae (cyanobacteria).
“Algae” is a word that gets lazily applied to any living thing that does photosynthesis but that isn’t a plant: from tiny glittering diatoms in a drop of pond water to giant kelp in the oceans. The other kind that I noticed in the South Skunk River this week is filamentous green algae, which forms slimy hair-like strands on rocks and globs on the water’s surface. Color is the least of the differences.
Cyanobacteria are tiny and simple. There’s strong evidence that the chloroplasts in the cells of plants and green algae are the captured descendants of cyanobacteria. This amazing phenonemon is called endosymbiosis, and it’s happened multiple times in the history of life on earth. If you’ve never heard of it, I’d recommend this YouTube video, which explains the concept with cartoons.
The practical reason to know if the green stuff in the water is cyanobacteria is because they can produce toxins. I wasn’t able to get a sample tested for microcystin (and chances are, this algae bloom will have dispersed by the time you read this), but I would recommend keeping your dog out of water that looks like paint or pea soup, to be on the safe side.
Why is the water so green, so early? Algae growth is limited by the availability of light, heat, and fertilizer–phosphorus in freshwater, and to a lesser extent nitrogen. We’re getting unseasonably warm weather before there’s any leaves on the trees to shade the water. As for the fertilizer, I’m not sure where it came from, or when. Rick Dietz and I tested nitrate and phosphate with field kits on Wednesday and measured 0 mg/L. Nitrate and phosphorus levels were also fairly low at this site when we collect grab samples in February. Maybe something was washed into the river earlier in the week, but it has since been used up by the algae or has washed downstream. I’ll amend this article if I find out something conclusive.
“With the Nutrient Reduction Strategy approaching its 10-year anniversary in 2023, Iowans deserve to see water quality results from the nearly $100 million of public money invested since 2013. Water monitoring is a crucial component to the success of the Nutrient Reduction Strategy and must be designed to assess progress. A strategy without a way to evaluate progress or outcomes is not a real strategy.”
Most water monitoring programs are NOT designed to assess progress. Often, people don’t begin monitoring in earnest until the grant funding arrives for an improvement project (or on flip side, until an industry with a reputation for pollution sets up shop in the area). Often, they’re hoping for preliminary results when the grant wraps in 3-5 years. I’ve been down that road, completed a horrifying statistical analysis, and left this conference poster as a warning to others: “Progress tracking is not a realistic use for typical stream monitoring approaches”.
Our local partners in Story County took this warning to heart and made a plan to sustain water monitoring for at least ten years, while shifting our focus. We collected lab samples from more sites (less often, and with less hassle) while ramping up the volunteer program, so we could engage the public and get a baseline understanding of water bodies all around the county. All is well and good. But now and then I come back to the question “how would you monitor water if you were serious about assessing progress?”.
Preliminary results in 3-5 years might be feasible if you already have baseline data for comparison, and account for any big changes in weather. The South Skunk River just upstream of Ames was monitored from 2001-2014 by the Iowa DNR, and we resumed monitoring it in 2020. I have good news and bad news for the newly formed Headwaters of the South Skunk River WMA.
Good news: average nitrate concentrations over the last three years have declined 46% compared to the baseline period. Mission accomplished?
Bad news: the trend goes away if you exclude samples collected during a drought when nitrate levels are at their lowest.
Study design is key for progress tracking. In order to be sure that water quality really changed, and to be able to link that change to something that happened in the watershed, scientists approach water monitoring like a medical trial. To do it right, there should be a treatment group (a watershed that receives conservation funding and attention), a control group (a nearby watershed that doesn’t receive funding), a before period, and an after period. There should be a full accounting of land management and conservation practices in both watersheds. If the treatment group improves more than the control group, that’s a good sign the medicine works. At the time we wrote the Story County Monitoring Plan, doing a paired watershed study of the sort that Michelle Soupir did for Black Hawk Lake didn’t make a lot of sense.
It didn’t make sense to invest in progress tracking, because our WQI-funded watershed project had come to a close, further funding was uncertain, and we couldn’t expect much improvement in water quality based on other metrics to date. Our watershed coordinators worked really hard, we had enthusiastic partners in local government and agribusiness, and we organized some well-attended field days where we heard from inspiring early adopters of cover crops and bioreactors. We met some farmers in the watershed who cared enough about soil and water to take a risk and try something new. Unfortunately, at the end of four years, we had a lot of unspent cost share funds and only enough conservation practices to expect or 1 or 2 percent reduction in nitrogen and phosphorus. Ioway Creek is a big watershed (147,000 acres).
However, this year I was reviewing our water monitoring data and had one of those moments like when you squint at an optical illusion and suddenly see a rabbit instead of a duck.
“Hey, that looks a lot like an upstream/downstream study for tracking whether projects in the Ioway Creek watershed and the City of Ames have improved water quality!”
The medicine: A bunch of conservation practices were installed between 2015 and 2019, some of which address nitrogen and some of which address other pollutants. We could include Jean’s no-till fields in Hamilton County, Jeremy’s cover crops in Boone County, Gerold’s bioreactor in Boone County, the UV disinfection system in Gilbert, the permeable parking lot at Ames City Hall, the stream restoration and saturated buffer at the Tedesco Environmental Learning Corridor, and many others.
The treatment group: A downstream site, influenced by all those conservation practices. The South Skunk River at 265th St. has been monitored weekly by the City of Ames since 2003. At this point the river drains 573 square miles, corresponding to the Ioway Creek watershed plus the Headwaters of the South Skunk River watershed.
The control group: An upstream site, not influenced by these practices. At this point, the river drains 316 square miles, corresponding to the Headwaters of the South Skunk River watershed, minus any land within Ames city limits.
A before period: Both sites were monitored between 2003 and 2014.
An after period: Both sites were monitored between 2020 and 2022.
And then I made a boxplot and squinted a little more and said, “Hey, it looks a lot like nitrate has improved at the downstream site!” Same thing for E. coli! Maybe there’s more to this story than just cost-share metrics.
The analysis is described in more detail in our 2022 annual report on water monitoring in Story County. We’ll also have some opportunities this year to talk with other groups around the state that are doing water quality monitoring and swap some tips and tricks.
Here’s one of mine. To see the “rabbit” in this data, you have to be flexible in how you think about watersheds. A watershed is just the land area that drains to a common point. With the right tools, we can delineate a watershed for any point of interest on the river network. I’ve taught several classes of ninth graders how to do this. Neither of these sites are in the Ioway Creek watershed, and they aren’t mentioned in the Watershed Plan, but that doesn’t mean they’re not relevant. The US Geologic Survey’s system for mapping and numbering watersheds is convenient for many purposes. But if you have access to long-term monitoring data, don’t be afraid to think outside the HUCs!
Jess Lancial testing water quality (photo credit Story County Conservation)
Volunteer Water Monitoring in Story County
A round of applause for all the volunteers and Story County Conservation staff who have diligently been monitoring their assigned stream twice a month in all kinds of weather! Also, let’s give a shout-out to the people who work behind the scenes. Sara Carmichael of Story County Conservation keeps everyone on track and equipped with supplies. Heather Wilson of the Izaak Walton League of America provides training and support to volunteers around the state. We rely on the IWLA’s Save Our Streams program for training materials and the Clean Water Hub for data entry. The three of us will be meeting the volunteers at a training event later this month to kick off another great season.
Three ways to get involved:
There’s room for one or two more volunteers to cover a site in Story County, so contact Sara.
If you’d like to try water monitoring without committing to a schedule, Prairie Rivers organizes a one-day volunteer event in the Ames area each May, so keep an eye on our events page.
If you don’t live in Story County, the Izaak Walton League is launching a new Nitrate Watch program and you can request a bottle of test strips while supplies last.
In March, Prairie Rivers will release a report detailing the findings, but for now let’s admire the scale and consistency of the effort, which has really improved since last year. (Updated 2023-02-18 to include some data sheets that were entered late)
2022 Season
Volunteers participating
Sites tested at least once
Sites tested at least 10 times
Sites tested at least 20 times
Data sheets entered in the Clean Water Hub
2021 Season
Volunteers participating
Sites tested at least once
Sites tested at least 10 times
Sites tested at least 20 times
Data sheets entered in the Clean Water Hub
Story County Water Monitoring & Interpretation Plan, 2021-2030
Prairie Rivers partnered with Story County and 8 other organizationsto develop a ten-year Water Monitoring & Interpretation Plan for Story County. Regular communication between the various groups testing water helps avoid duplication and leads to new opportunities to improve water quality. Planning for how data can be used over the long term ensures that we get the most value from our time and effort. Read the plan here.
We know that weather influences water quality in Iowa’s rivers. Last year, there was a drought and nitrate was lower than usual. This spring, it’s been wetter and nitrate is higher than usual. If you monitor for 10 years and the first 5 are a little wetter or drier than the last five, you’ll a water quality trend to go with it. Boring!
What we really want to know is how people are influencing water quality. We can get a lot closer to that answer by peeling away the obvious weather-related patterns to reveal underlying trends.
In statistics, it’s called a covariate or an explanatory variable. If there’s a relationship between your water quality metric and some other thing you’re not really interested in (i.e. streamflow), you can model that relationship to account for part of a water quality trend over time. What’s left over might be the things you’re really interested in (i.e. how water quality has been affected by changes in crop rotations, conservation practices, sewage treatment, manure management, and drainage). It’s common enough in the scientific literature (Robert Hirsch’s Weighted Regression on Time, Discharge, and Season is a good example), but should be used more often for progress tracking at the watershed scale.
To illustrate this general approach, I downloaded daily nitrate data from three stations maintained by the US Geologic Survey. The sensors at the Turkey River at Garber and the Cedar River near Palo (north of Cedar Rapids) were installed in late 2012; the sensor Raccoon River near Jefferson was installed in 2008. I wanted a high frequency dataset (to minimize sampling error) that included the episodes of “weather whiplash” in 2013 and 2022.
“Residuals” are the difference between what we predict and what we measured. In the first panel, that’s the difference between a measurement and the long-term average. In the second and third panels, we see how nitrate measurements differ from what we’d expect given flow in the stream today, and flow in the stream last year. Gray dots – daily measurements. Red dots- yearly averages. Blue dotted line – trend. If I did this right, some of the dots should get closer to the middle.
Nitrate concentrations in rivers increase as the weather gets wetter and streamflow increases… up to a point. When rivers are running very high, there’s a dilution effect and nitrate concentrations fall. Based on that relationship, we can explain high nitrate levels in the Cedar River in 2016 (a wet year) and low nitrate levels in 2021 (a dry year).
Nitrate concentrations tends to be highest on wet spring days following a dry summer and fall, as nitrate that accumulated in the soil during the drought is flushed into drainage systems or washed off the land surface and into rivers. Here I’ve calculated a moving average of flow over the previous 365 days, and compared that to nitrate concentrations during high flow or low flow conditions. Based on that relationship, we can explain high nitrate in the Cedar River on wet days in the spring of 2013 and 2022 (following a dry year) and low nitrate on wet days in the spring of 2019 (following a wet year).
After making these adjustments, the downward trend in the Cedar River looks much smaller (0.53 mg/L per year, adjusted to 0.25) and is overtaken by the Turkey River (0.37 mg/L, adjusted to 0.28). The adjusted trends are statistically significant and could be attributed to conservation efforts in those watersheds.
How did I do this? For technical details, read here.
However, there’s still some weather-related patterns we haven’t accounted for. The Raccoon River near Jefferson also had a steep decline in nitrate since 2013 (1.42 mg/L per year, adjusted to 0.77 mg/L per year) but if you look at the entire record (going back to 2008), it’s part of an up-and-down cycle. I’ve seen that same pattern in the South Skunk River. The model explains some of those swings but doesn’t fully explain high nitrate in fall of 2014, spring of 2015 and spring of 2016. Perhaps the nitrogen that accumulated in the soil during the drought of 2012 took several years to flush out.
In addition to streamflow and last year’s weather (antecedent moisture is the technical term), nitrate can be explained by season, soybean acreage, and baseflow. If it’s not enough to know that water quality is improving or getting worse, and you’d also like to know why, then let’s peel that onion!
Ioway Creek recently got some love from the community. On Saturday, May 21, a group of seventeen volunteers (plus another four helping on land) loaded nine canoes with trash as we floated from Brookside Park down to S. 16th Street in Ames. We hauled out 14 tires and 1,560 pounds of other trash including 3 shopping carts, a tent, and two bicycles. Assembling the tools, canoes, food, and people was a collaborative effort involving Prairie Rivers of Iowa, the City of Ames, Story County Conservation, the Skunk River Paddlers, and the Outdoor Alliance of Story County. A few people got wet, everyone got dirty, my muscles are still sore, but we all had a good time on the river!
Citizen Science
On Tuesday May 17, fourteen volunteers tested water quality in Ioway Creek and its tributaries. This is the fifteenth Spring Watershed Snapshot, and the fourth that Prairie Rivers organized. Thanks to the Outdoor Alliance of Story County for help with supplies. This year, some volunteers were already doing regular monitoring of a site for Story County Conservation and adjusted this month’s schedule to coordinate, or picked up a few extra sites. If we include other watersheds and other days tested during the same week, the count is 22 volunteers (and also some Story County Conservation staff) and 47 sites in Story, Boone, and Hamilton counties.
We scheduled the event for a weekday this year to coincide with Polk County’s snapshot, so while the event was less social than it sometimes is (volunteers could pick up a kit any time on Tuesday and test their assigned sites alone or with a friend), they were monitoring as part of a big coordinated effort of the kind that we haven’t seen since before the IOWATER program was cancelled! In Polk County, 75 people covered 115 sites!
A table with our findings are shown below, and a map of the sites can be found here. On Tuesday, the water was clear and phosphorus was low at all our sites. Chloride was highest and nitrate lowest in creeks with more urban watersheds. Dissolved oxygen fell into the “fair” range at several sites in Hamilton County, as well as the south fork of Worrell Creek in Ames. Nitrate was 10 mg/L or higher at most sites, but reached 20 mg/L in the middle sections of Ioway Creek and several rural tributaries. I did some followup testing to make sense of the high nitrate levels at Duff Ave, more on that later.
Thanks to all the volunteers who spent some time in a creek last week!
Prairie Rivers of Iowa has just released an annual report investigating water quality in streams and lakes around Story County. Prairie Rivers of Iowa worked with Story County Conservation, the City of Ames, and other partners in 2020 to initiate a locally-led water monitoring program including both volunteer and laboratory testing.
The report’s author Prairie Rivers of Iowa Water Quality Specialist Dan Haug states, “Our partners and volunteers have gone to a lot of trouble to test rivers and lakes across the county, so we take seriously the job of interpreting the data.” He continues, “It’s only the second year of the program, but we’re starting to see patterns that can help us evaluate nutrient reduction efforts and improve our streams for recreation and fisheries.
Volunteer Rick Dietz and Prairie Rivers of Iowa Board President Reed Riskedahl test phosphorous in a tributary of Ioway Creek.
Some of the key findings detailed in the report include the risks of waterborne illnesses, algae blooms in lakes and streams, the impacts to aquatic life and the effects of excess nutrients being sent downstream, eventually to the Gulf of Mexico.
“The water monitoring planning team is working hard to bring together all the resources we can to conduct monthly water testing, equip volunteers, educate elected officials and the public about the many water quality issues in our lakes, rivers and streams,” according to Haug.
In 2021, E. coli bacteria was usually low at swimming beaches and parts of the South Skunk River, but high in most creeks. The influence of nitrogen and phosphorus loads from Story County did not have as much influence on hypoxia contamination to Gulf of Mexico in 2021 due to a dry year, but the plan calls for continued monitoring to determine the effects during normal to wet periods helping to identify hot spots and evaluate whether conservation practices are working.
Water quality monitoring results in Story County did however reveal that during dry conditions in 2021, the highest levels of nitrogen and phosphorus were found below wastewater treatment plants. Wastewater effluent may be contributing to low dissolved oxygen levels in some streams harming aquatic invertebrates yet more monitoring is needed to establish patterns.
Other findings during the past year conclude that untreated stormwater from older neighborhoods has extremely high levels of sediment, phosphorus and bacteria.
Water monitoring was guided by a ten-year plan written by nine local partners and facilitated by Prairie Rivers of Iowa.
Water samples were collected monthly from 15 sites and weekly from three sites, with laboratory support provided by the City of Ames. Story County Conservation launched a volunteer monitoring program with 17 individuals and one business participating. Prairie of Iowa used special hardware to collect samples of runoff from rainstorms.
