Drainage districts have power to improve water quality


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One-third Iowa cropland is a part of a tile drainage system, which are regulated by drainage districts. (USGS)
Jenna Ladd | October 12, 2017

A new report out of a non-partisan Iowa City-based research center, Iowa Policy Project, states that drainage districts have the power to improve water quality in the state.

About one-third of cropland in Iowa is tiled for drainage. Agricultural drains channel water, which often carries heavy nitrate loads, from fields into local water waterways. Iowa’s nitrate runoff is a primary contributor to the growing Dead Zone at the mouth of the Mississippi River.

Researchers Sarah Garvin, Michael Burkart and David Osterberg recommended using Iowa’s “quasi-governmental” drainage districts an agent of change. The report explains that the districts have the statutory authority to mitigate nitrate runoff by “requiring water quality monitoring and reporting, wetland conservation and restoration, and mandating the installation of bioreactor at discharge points to reduce nitrate loads.”

The report also points out that under statutory mandate, drainage should be “a public benefit and conducive to the public health, convenience and welfare.” Nitrate levels in water at or below the Environmental Protection Agency’s standard of 10 mg/L is considered safe for consumption. However, some new research suggests that nitrate levels below this can pose some health threats. In either case, the report reads,”Public health and welfare should be interpreted to mean keeping our waterways free of nitrate pollution.”

David Osterberg, lead energy and environment researcher at Iowa Policy Project, said, “It’s going to require managers of drainage districts to step up at a time when their county supervisors cannot, even if they wanted to, and at a time the state legislature has stood in the way of local authority on industrial agriculture.” He added, “In this case, with drainage districts, the authority to take some steps already exists.”

The executive summary and the full report can be found here.

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