Adam Shriver is Director of Wellness and Nutrition at the Harkin Institute for Public Policy and Citizen Engagement. This essay was first published on his Substack newsletter, Canary in a Cornfield.
Iowa has a serious problem with nitrates in our drinking water that we’ve known about for decades, and these problems are only getting worse. Numerous studies—extremely high-quality studies—and detailed accounts of underlying biology all present a strong case that nitrates levels in drinking water lower than the current 10 mg/L NO3-N standard are linked to different types of cancer. We discussed that research in my interview with the Chair of a Denmark Ministry of the Environment Report, and the recent Cancer and Environmental Risk Factors in Iowa report covered those studies in detail.
For that reason, it’s extremely important for Iowans to have the best possible data measuring the amount of nitrate in our drinking water throughout the year.
Despite the urgency of the problem, the Iowa legislature cut off funding to the the University of Iowa’s IIHR Hydroscience and Engineering Water Quality Information System in 2024. The Walton Family Foundation agreed to step in and fund the network for two years, but they were very clear that this was only a temporary measure. In short, they were giving Iowa a couple years to get ourselves together.
What that means now: if the legislature does not restore funding in the state budget for fiscal year 2027, many of the sensors in the IIHR network may need to be removed or discontinued, putting Iowans at risk.
There currently is a lot of public pressure to restore funding. A recent poll showed Iowans are understandably extremely concerned about their drinking water and the risk of cancer.
Because of that pressure, some legislators have suggested approaches that may create the appearance of taking the problem seriously, while nevertheless removing the key source of real time information about nitrates. For example, after constituents asked one legislator to fund the IIHR network, that lawmaker responded with a power point presentation about the Iowa Department of Natural Resources’ Ambient Water Monitoring Program. Some legislators appear to believe the DNR program can serve as a substitute for the IIHR network.
The Ambient Water Monitoring Program checks certain water bodies around the state only once a month, and sometimes even less frequently (quarterly), whereas the IIHR network is a continuous monitoring network with sensors placed under the surface of water bodies like rivers or streams. These sensors transmit information that’s available almost immediately, every 15 minutes.
I’ve also heard the legislature would like to wait until the U.S. Geological Survey completes a new study, under contract from Iowa State University, the Iowa DNR, and the Iowa Department of Agriculture and Land Stewardship. The concept is that lawmakers would be able to compare the data from the two water monitoring programs before deciding whether to fund the IIHR network.
One legislator apparently believed the new study could be completed within six months, but others have projected that it might take more than three years. It seems like someone is sharing bad information (which would bother me quite a bit if I were an elected official).
It’s important to note that we already know the DNR program is not an adequate substitute for the IIHR network. The IIHR provides both immediate data as well as importantly different data. Regarding the timing, author and water quality expert Chris Jones recently wrote,
Comparing the sensors to the DNR program, however, is like comparing apples and planting an apple tree. DNR data are not daylighted for public consumption for sometimes months after samples are collected, analyzed in a laboratory, and data posted onto the DNR web portal, which is nightmarish for lay people to navigate.
Given that there’s strong evidence that nitrate levels even below the EPA required limit of 10 mg/L are linked to cancer, Iowans deserve to know when those levels are higher in time to respond to that information. It doesn’t help me much to learn in March that I was drinking water at 9.99 mg/L NO3-N throughout the month of January!
Equally important: there are already studies examining whether the continuous network provides important information, and they concluded yes! For example, in a 2019 report by the USGS and the Iowa DNR describing the ideal approach to monitoring nitrate and phosphorous loads, it was acknowledged that:
Load-calculation methods based on infrequent (weekly to monthly) samples may not be accurate enough to assess interim progress toward load reduction goals because load-calculation estimation errors can be quite large.
Moreover, the report stated (emphasis added):
In contrast, monitoring with continuous data improves accuracy of load calculation (Cassidy and Jordan, 2011; Duan and others, 2014; Jones and others, 2012; Jones and others, 2018; Pellerin and others, 2014; Reynolds and others, 2016; Rozemeijer and others, 2010; Terrio and others, 2015). Jones and others (2012) demonstrated about a 10-fold improvement in the accuracy of assessing phosphorus regulatory compliance, as percent of time exceeding a concentration-based criterion, based on daily versus monthly data. Reynolds and others (2016) showed precision improved 9–12 percent for multiple metrics—mean concentration, exceedance of concentration-based criterion, peak concentrations, and total loads—with nitrate sampling frequency increased from monthly to daily.
Similarly, another report published in 2016 by DNR, IDALS, ISU, and IIHR—most of the same groups that are supposed to be involved in the new study—found (emphasis added):
[I]t may be possible to eliminate altogether the need for load estimation models for both nitrate and phosphorus by using in‐stream sensors (Feng et al., 2013; Davis et al., 2014). Although sensors require periodic maintenance and calibration they provide actual measurements of pollutant concentrations on a nearly continuous basis. When coupled with stream flow measurements made at or near the location of each sensor, loads can be measured rather than estimated.
And specifically about phosphorous, another important chemical to track:
The data sets indicate that the monthly frequency of monitoring at fixed‐station sites is not sufficient to estimate phosphorus loads because the amount of phosphorus in rivers and streams changes very rapidly with changes in stream flow. It is unlikely that phosphorus load estimates can be obtained without event‐based sampling or continuous monitoring.
These studies have already disproved the claims that (1) the DNR sensors can be a substitute for the IIHR network, and (2) that we need more studies to determine whether there’s any value to the continuous monitoring network.
Finally, it’s important to note that the network could already be funded without any additional burden on taxpayers, via a surplus of money in the same fund that originally provided funding prior the the legislature’s defunding! From Todd Dorman’s recent column for the Cedar Rapids Gazette:
One possible source of funding is the state’s Groundwater Protection Fund, which contains fees paid on nitrogen-based fertilizer sales, license fees from pesticide dealers, and registration fees for the sale of pesticides, among other sources.
The fund ended fiscal 2025 with a carry forward balance of $23.5 million, according to the nonpartisan Legislative Services Agency.
As Chris Jones noted, at an annual cost of about $500,000, this would be “enough to fund the sensor network for roughly 50 years.” I’ve heard the Groundwater Protection Fund has about $18 million after you take into account other expenses, but the basic point still holds: we already have enough money to fund the monitoring network for a long time.
Moreover, the Groundwater Protection Fund is replenished by commercial fertilizer registration fees and pesticide registration and licensing fees. A real-time monitoring network that tracks where fertilizers and pesticides are ending up (the waterways) seems like a great way to use those fees.
So please don’t buy the line that funding or studying the DNR network is or could be a substitute for the invaluable service provided by one of the most sophisticated water monitoring networks in the world. Or that the IIHR network would be some tremendous burden to taxpayers.
More water monitoring resources
For additional information about the importance of the IIHR nitrate sensor monitoring network, please take a look at the following:
Larry Weber’s presentation to Jefferson County Farmers and Neighbors about the importance of the continuous real-time nitrate sensors.
My interview with Tim Wagner from Decorah, discussing why the IIHR sensors are vital for public health there. He recounted how a manure spill could easily have been discovered long after residents were drinking nitrate levels well above 10 mg/L.
And in a set of comments from Danial Haug of Prairie Rivers of Iowa to the DNR about their Impaired Waterway List, he writes the following, which is a little technical but demonstrates the importance of the IIHR sensors:
There is a USGS sensor near Palo that measures nitrate continuously, except during the winter. Even if nitrate stayed low during the periods when the sensors were removed, we can say with certainty that nitrate concentrations exceeded 10 mg/L for at least 11% of the sample period (122 of 1096 days). This river segment was listed as Fully Supporting drinking water only because the DNR is using a dubious methodology and ignoring some of our best available data.
If the DNR insists on treating nitrate as a Class C binomial parameter, we recommend that they work with the USGS and IIHR—Hydroscience and Engineering to approve a quality assurance plan so that higher frequency data from nitrate sensors can be used. Waters that exceed 10 mg/L more than 10% of the time but that do not meet the bar for statistical significance because of limited data should be placed on the Waters in Need of Further Investigation list, and then investigated within a reasonable timeframe.