Perks of Reducing Nitrates

Study Details Benefits of Iowa's Nutrient Reduction Plan

Russ Quinn
By  Russ Quinn , DTN Staff Reporter
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There are 230,000 people in Iowa, or just about 8% of the population, who rely on private wells for their source of drinking water. (DTN/The Progressive Farmer file photo by Jim Patrico)

OMAHA (DTN) -- A plan to reduce nutrient runoff into Iowa's waterways could also help reduce nitrate levels in local water utilities and homes with private wells, according to a researcher at the Iowa State University.

The Iowa Nutrient Reduction Strategy (NRS), first released in November 2012, lays out a plan for reducing nutrient delivery to waterways in Iowa and further downstream.

In an Iowa Learning Farms (ILF) webinar on Wednesday, Chuan Tang, a postdoctoral research associate with the Center for Agricultural and Rural Development at Iowa State University (ISU), detailed some of the costs of having a high level of nitrates in drinking water sources, as well as the benefits of meeting the NRS targets.

The study, titled "Economic Benefits of Nitrogen Reductions in Iowa," also takes a look at the recreational benefits of keeping the state's water sources clean.


Tang said roughly 2.8 million people in Iowa, or about 90% of the population, receive their water from 1,874 water supply systems, 1,285 of which serve rural communities. Fifty-five percent of the water supply systems rely on groundwater, while the remaining 45% utilize surface water.

All of these systems must meet EPA-allowed maximum containment levels (MCL). The nitrate MCL allowed for drinking water is 10 milligrams per liter, Tang said.

Many water supply systems, often smaller ones, have shallow wells to pull water, and a majority of historical nitrate MCL violations come from these sources, according to Tang. Nitrate violations rose through the 1990s, peaked in 2003 and have steadily declined since this time.

"Small public water supply systems often lack the budget to invest in nitrate treatment technologies," Tang said. "As such, nitrates often remain a systemic problem for these utilities."

Tang said public water suppliers have several different options for removing nitrates from the water supply. However, treating nitrates can be a costly operation. The NRS could ultimately allow certain utilities to spend less money on limiting nitrates.

Many public water supply systems have to invest in nitrate-removal systems, either with ion exchange systems or reverse osmosis systems. Both technologies separate and then remove nitrates in drinking water.

Nitrate removal systems, while effective at reducing nitrate levels, are fairly expensive to maintain, he said.

A small public water system (serving 501 to 3,300 people) would face an annual total cost of $280,000 with the ion exchange system, while a medium utility (3,301 to 10,000 people) could see costs closer to $2.4 million and a larger one (10,001 to 100,000 people) could cost around $20 million. The annual costs for the reverse osmosis system is even higher, running $1.2 million, $4 million and $40 million for each of the different sized public water systems.

"It is double the cost with the reverse osmosis systems compared to an ion exchange systems," he said.

Tang also touched on private wells in his talk.

There are 230,000 people in the state, or just about 8% of the population, relying on private wells for their source of drinking water. Unlike public water supply systems, private wells are not regulated by the EPA or the state.

While the state offers water quality testing services for homes with a private well, homeowners are ultimately responsible for the safety of their water, he said.

Tang said data from various sources suggests as little as 7% and as much as 25% of Iowa's wells may contain unhealthy nitrate levels. Well owners should invest in testing the water in their well if they are concerned about the quality of their drinking water, he said.


The other major focus of the ISU study was to examine the recreational benefits of NRS. For many small Iowa towns, improving water quality can also mean more local business opportunities, Tang said.

In 2014, ISU's Center for Agriculture and Rural Development conducted a statewide survey of households' recreational trips to the state's lakes. The survey was mailed out to 7,000 Iowa households with about half being returned.

About 60% of those who responded to the survey reported they visited at least one lake in the state in 2014. Twenty percent reported at least one overnight trip to a state lake during the year.

Tang said researchers estimated in their model that Iowans would be willing to spend $30 million per year for recreational improvements from the better water quality associated with full implementation of the NRS.

Their model quantified and statistically controlled for the effect that various attributes of lakes have on the choice of which lake the household chooses to visit. These attributes include the lake size, distance from the home, water quality, boat ramps and other relevant features. The model also controls for household characteristics such as family composition, income and other observable traits.

Despite the data gained from the study, Tang said continued ongoing research is needed on the issue of water quality in the state.

"I think we need more research to better understand the potential impacts of such policies as NRS," Tang said.

ILF was established in 2004 and is a partnership of several Iowa entities. The Iowa Department of Agriculture and Land Stewardship, Iowa State University Extension and Outreach, Leopold Center for Sustainable Agriculture, Iowa Natural Resources Conservation Service (NRCS) and the Iowa Department of Natural Resources all make up ILF.

The study was led by Tang and Gabriel Lade, ISU assistant professor of economics. Others involved with the study included David Keiser, assistant professor of economics; Catherine Kling, director of the Center for Agricultural and Rural Development; Youngjie Ji, an assistant scientist and Yau-Huo Shr, a postdoctoral researcher.

To read the complete ISU report, click on…

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Russ Quinn