Reducing Nitrates Offers Perks

Iowa's nutrient-reduction plan shows promise for local and private water sources.

Russ Quinn
By  Russ Quinn , DTN Staff Reporter
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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, a researcher ‌at Iowa State University (ISU) explains.

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

In a recent Iowa Learning Farms (ILF) webinar, Chuan Tang, a postdoctoral research associate with the Center for Agricultural and Rural Development, at Iowa State University, 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.

HIGH COSTS. Tang says roughly 2.8 million people in Iowa 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), with the nitrate MCL allowed for drinking water at 10 milligrams per liter, Tang says.

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, Tang explains. 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 says. “As such, nitrates often remain a systemic problem for these utilities.”Tang says 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.

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

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 are even higher, running $1.2 million, $4 million and $40 million for each of the different sizes of public water systems.

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 says.

Tang explains data from various sources suggest 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 wells if they are concerned about the quality of drinking water, he warns.

ADDITIONAL RESEARCH. Despite the data gained from the study, Tang says 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 says.

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.

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

For More Information:

Economic Benefits of Nitrogen Reductions in Iowa


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