These Two Things Are Not the Same

There are Already Studies Showing Iowa's DNR Ambient Water Monitoring Program is Not an Adequate Substitute for IIHR's Continuous Water Quality Monitoring Network

(Updated 4/8/26 with video presentation from Larry Weber, Director of IIHR)

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. As explained in my interview with the Chair of a Denmark Ministry of the Environment Report and covered in detail in the recent Cancer and Environmental Risk Factors in Iowa report, there are numerous studies, extremely high-quality studies, and detailed accounts of underlying biology that 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. For this reason, it’s extremely important that Iowans have access to the best possible data detailing the amount of nitrate in our drinking water throughout the year.

Despite this, the Iowa Legislature cut off funding to the the University of Iowa's IIHR Hydroscience and Engineering Water Quality Information System two years ago. 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. And what that means now is that if the legislature does not restore funding this year, 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, as Iowans are understandably extremely concerned about their drinking water and the risk of cancer (as indicated in a recent poll). In response to this pressure, there have been a couple suggestions that seem designed to make it look like the problem is being taken seriously, while nevertheless removing the key source of real time information about nitrates (the IIHR network). For example, after a request to fund IIHR from constituents, one current legislator responded only with a power point presentation about the Department of Natural Resources (DNR) Ambient Water Monitoring Program, and there have been suggestions that some legislators believe that 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. A related thing I’ve heard is that the legislature would like to wait until a new study is completed by the US Geological Survey (USGS), under contract from Iowa State University (ISU), the Iowa Department of Natural Resources (IDNR) and the Iowa Department of Agriculture and Land Stewardship (IDALS) comparing the data between the DNR and IIHR programs before making funding decisions about the latter. One legislator apparently believed the new study could be completed within six months, but some other estimates have suggested that it might take over three years, so it seems like someone is sharing bad information (which would probably bother me quite a bit if I were an elected official).

It’s very 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 actually 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!

But equally important is the fact that 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:

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 2016 by DNR, IDALS, ISU, and IIHR (most of the same groups that are supposed to be involved in the new study) found:

It 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.

So 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, have already been shown to be wrong.

And 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:

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 Jones notes, 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 has about $18 million after you take into account other expenses, but still the basic point still holds that 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 pesticides registration and licensing fees, and it seems like a great use of fertilizer & pesticide fees is tracking where a lot of it ends up - in the waterways - with a real-time monitoring network.

So please don’t buy the line from anyone 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 this would be some tremendous burden to taxpayers.

Update: Here’s a link to Larry Weber’s presentation to Jefferson County Farmers and Neighbors about the importance of the continuous real-time nitrate sensors :