Project name: North Thompson Watershed size: 111,600 acres Year began: 2005 Year Complete: Ongoing SWCD Contact: Adair Phone: (641) 743-6124
Purpose: Improve water quality Soil and Water Conservation District(s): Adair, Madison, Union Other partners: Iowa Department of Agriculture and Land Stewardship, Iowa Department of Natural Resources, USDA Natural Resources Conserva- tion Service, Iowa State University Extension, Iowa Farm Bureau, Farm Service Agency, local banks

Phil Patterson stretches the conservation money he administers from the Iowa Department of Agriculture and Land Stewardship as far as he can. In fact, he can tell you the cost of trapping a ton of sediment for every practice he helps apply in the North Thompson River Water Quality Project in Adair County.

Patterson, an Environmental Specialist, runs sediment delivery calculations for every application for state cost-share funds in the project. The North Thompson project has sediment reduction as its primary goal.

“In fiscal year 2009, it cost $83.30 a ton to trap 2,450 tons of sediment,” Patterson says. Practices included grade stabilization structures, terraces, water and sediment control basins, and grassed waterways. Other state and federal conservation programs were used in the project area, including the Conservation Reserve Program and Iowa Buffer Incentive to apply contour conservation buffers.

Patterson has found that watershed dams top the list in trapping sediment most economically. “If you look at the cost of trapping a ton of sediment each year for the life of a structure, that cost is minimal for the benefits the structure provides,” Patterson says. “For example, a dam built in 2007 to trap sediment on the Chuck Green farm cost the watershed $24,987. It is trapping 689 tons of sediment a year, at a cost of $36.27 a ton. But over the life of the dam, it will cost only $1.04 a ton.”

While Patterson looks at sediment reduction, most landowners look at other advantages. In Chuck Green’s case, he likes the fishing and view of his 12-acre lake.

One in a series of summaries of watershed projects in Iowa carried out by local conservation districts, the Iowa Department of Agriculture and Land Stewardship, Division of Soil Conservation, and other partners.

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