Saving Resources: Manure and Water
Assessing Agricultural Policy Implications for the Mississippi River Basin


Full report or 19-page PDF, includes executive summary)
Executive Summary or 2-page PDF
This News Release (2-page PDF)

IOWA CITY, Iowa (May 4, 2016) — Iowa falls short in limiting manure runoff into lakes and streams when soil conditions are unfavorable, and could learn from another Midwestern state to create better protection of water flowing to the Mississippi River.

“Iowa does not place strong limits on manure application on frozen, snow-covered or saturated ground. The state has too few inspectors, and the rules can be confusing to farmers who are expected to follow them,” said David Osterberg, founder of the nonpartisan Iowa Policy Project (IPP) and co-author of a new report.

“Keep in mind manure is a good resource to fertilize cropland. But it doesn’t do any good for farmers when it cannot permeate frozen ground, or is lost because the ground is saturated.

“There are so many exemptions and caveats in Iowa law that they undermine state rules designed to lessen runoff.”

The report, available at, examines Iowa policies in relation to research about the consequences of ag-based pollution in Iowa waters and in the dead zone where the Mississippi River empties into the Gulf of Mexico.

It also looks at steps taken by the state of Ohio in response to serious issues in that state. The report recommends for Iowa:

• An outright ban on manure application in liquid form from medium and large animal production facilities when the ground is frozen or snow-covered.
• An outright ban when the top two inches are saturated from precipitation or when weather is expected that will be detrimental to the environment and to the utilization of the manure.
• Ample “boots on the ground” enforcement capabilities with long-term funding allocated to maintaining adequate staffing.
• Immediate adoption of restrictions on all operations at 300 animal units (AU) or more for manure application during unfavorable soil conditions.
• Progress toward placing application restrictions on all facilities above 100 AU in size.

“Iowa should be proactive on this issue,” said Nick Fetty, a University of Iowa graduate student and co-author of the report with Osterberg and UI graduate student Nathan Wong. “The reaction in the state of Ohio, after a large city lost its drinking water system because of pollution, led to stronger laws to limit both farm and urban runoff. Iowa does not need to wait for the same thing to happen here.”

Osterberg noted the latest session of the Iowa Legislature included much discussion — but no action — on funding alternatives to improve water quality.

“Assuring good water quality can be complex, and effective public policy needs to include not only funding, but approaches to both incentivize and require good soil management practices,” Osterberg said. “Addressing the question of manure application has to be part of the package — it’s really one of the most obvious pieces of a solution.

“We have to stop winking at the problem with weak regulations and shrugging our shoulders when someone makes a mistake. We have to make sure the mistakes don’t happen, and that starts with a ban.”

While much of the attention in Iowa about agricultural sources of water pollution has focused on the negative impact on cities in the state — particularly the Des Moines area and a high-profile lawsuit — a broader concern is for the impact on the Mississippi River and states downstream.

Nutrient runoff is part of the cause of is the hypoxic region, or “dead zone,” in the northern Gulf of Mexico. Hypoxia in the Gulf is caused by excess nitrogen and phosphorous delivered by the Mississippi-Atchafalaya river system. Some of those nutrients come from manure.

“By reducing runoff caused by inappropriate manure application, the nutrient load to the hypoxic zone could be significantly reduced,” the report stated.

The Iowa Policy Project is a nonpartisan, nonprofit public policy analysis and research organization in Iowa City.

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