Project name: East Boyer River Watershed size: 83,840 acres Year began: 1999 Year Complete: Ongoing SWCD Contact: Crawford Phone: (712) 263-4123 Purpose: Reduce flooding
Soil and Water Conservation District(s): Crawford Other partners: Iowa Department of Agriculture and Land Stewardship, Crawford County Board of Supervisors, City of Denison, US Army Corps of Engineers, Natural Resources Conservation Service, Federal Emergency Management Agency

The simple goal for the East Boyer River Flood Control Project was to get up the morning after strong thunderstorms and go to work like any normal day, instead of cleaning up after flooding.

After the city of Denison was flooded 3 times in the 1990’s, residents repeatedly listed upland watershed treatment as their top choice to reduce flooding. This project assisted in doing just that––building 32 small to medium sized detention dams over a 10-year period.

In 1999, the first dam was built. The Iowa Department of Agriculture and Land Stewardship (IDALS) covered 75 percent of the cost with Watershed Protection Funds, but required local sources to pay the other 25 percent. The city of Denison paid up to $1,000 for each dam, as an incentive for private landowners. Crawford County followed suit, paying about $5,000 on average for each dam, to protect county roads and bridges and to reduce flooding. Landowners paid an average of $4,000 for each of the dams.

The bottom line for Denison is that a river that flooded the city three times in five years, after levee and small detention dam construction, would be expected to flood the city again no more often than once every 250 to 500 years. The levees offered 100-year protection plus 3 feet of freeboard. The small dams decreased peak flows by at least 15 percent. Added together, the levee and small dams now offer total flood control benefits.

Secondary benefits of the dams include gully erosion control, secondary road protection, and new water sources for wildlife, recreation, and livestock.

The dams and water absorption practices like no-till, practiced by farmer Dale Snyder, above, help local project supporters smile these days (below).

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.

Return to Iowa Watershed Projects