Iowa's Low Hanging Fruit

Stream Buffer Rule = Cleaner Water, Little Cost

Tuesday, February 3, 2015

By Soren Rundquist, EWG Landscape Analyst, Craig Cox, EWG Senior Vice President and Patrick Mason, GIS Analyst

Iowa's Low Hanging Fruit

Stream Buffer Rule = Cleaner Water, Little Cost

A study of five representative Iowa counties shows that requiring simple buffer zones between crop fields and streams could get two-thirds of the way to the state’s goal for reducing phosphorus pollution and one-fifth of the way to the nitrogen pollution target, while affecting only a tiny proportion of landowners and a vanishingly small percentage of row-crop acreage.

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The 2013 Iowa Nutrient Reduction Strategy committed the state to an ambitious goal of reducing phosphorus pollution from so-called nonpoint sources – mostly farm operations – by 29 percent, and nitrogen pollution by 41 percent. The science assessment that accompanied the strategy concluded that the simple step of putting 35-foot-wide grass strips between waterways and adjacent cropland could cut phosphorus runoff by 18 percent and nitrogen pollution by 7 percent.

Environmental Working Group used high-resolution aerial photography to assess the impact on Iowa’s farms of implementing streamside buffer standards of varying widths – 35 feet, 50 feet or 75 feet in Allamakee, Hamilton, Linn, Plymouth and Union counties

Picture showing missing stream buffer

Source: National Agricultural Imagery Program, 2014.

Enacting a streamside buffer standard would affect only a handful of landowners and an almost undetectable effect on land in row crop production.

  • Requiring a 35-foot buffer would affect only 8 percent of landowners and convert only 0.05 percent of corn and soybean acres in those counties.
  • Even a 75-foot standard would affect only 13 percent of landowners and convert only 0.29 percent of corn and soybean acres.
  • Seventy-one percent of landowners could meet the 50-foot standard by planting an acre or less to a grass buffer.

To EWG, that sounds like very low hanging fruit. Planting narrow strips of grass between cropland and waterways doesn’t seem too much to ask of landowners to jump start cleaning up Iowa’s chronically dirty water.

If Iowa is serious about cleaning up its waterways, enacting a streamside buffer standard of at least 50 feet would be an excellent way to start. Counties could take the initiative even in the absence of state action. See for yourself what we found:


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