Policy makers tour Upper Cedar Watershed
By Jean Caspers-Simmet
simmet@agrinews.com
Date Modified: 10/24/2011 5:44 PM
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CHARLES CITY, Iowa — Forty legislators, mayors, county supervisors and soil and water conservation district commissioners attending the recent Upper Cedar River Watershed Tour in Floyd County.
Organized by the Floyd County Soil and Water Conservation District, the tour included urban and agricultural soil and water conservation practices aimed at controlling flooding, pollution and soil erosion in the Cedar River basin.
The tour was sponsored by Floyd, Bremer, Mitchell and Butler Soil and Water Conservation Districts, the Iowa Flood Center, the University of Iowa, the Natural Resources Conservation Service and the Department of Natural Resources.
Flood Center associate director Nathan Young provided an overview of the center, which was created in 2009. Researchers there have designed a sensor network to better monitor stream flow, and they have also improved the use of radar data for precipitation measurement to better predict floods. Young demonstrated the Iowa Flood Information System, which provides flood conditions and forecasts.
Standing on a pedestrian bridge over the Cedar River, Tom Brownlow, Charles City administrator, described Charles City's new whitewater park. The land was acquired through flood buyouts and includes 26 acres of land along the Cedar River and 11 acres of water. To construct the whitewater course, the city shaved off the top of an old low head dam and enhanced the area with rock.
Kayakers have come from across the country.
"But tubers are where we're getting the most action," Brownlow said. "A local gas station rents inner tubes and life jackets. He sells out every day during warm weather."
Brownlow also led a tour of the city's 17-block Green Streets Project, which created a rainwater treatment system using porous unit paving, cobble infiltration areas, amended soil infiltration areas and alley trench gates. The streets reduce the volume of stormwater by 100 percent during small rain storms and over 50 percent during large storms.
Just south of Iowa State University's Northeast Research Farm at Nashua, the group visited a Conservation Reserve Program Enhancement wetland consisting of a six-acre wetland surrounded by 20 acres of native grasses and forbs.
The CREP is a partnership between the Department of Agriculture and Land Stewardship, the Farm Service Agency and local soil and water conservation districts, said Shawn Richmond, IDALS CREP coordinator. Through the program landowners voluntarily establish wetlands in the heavily tile-drained regions of Iowa. These strategically placed wetlands reduce nitrate loading by more than 40 percent to 70 percent.
Over the past decade, 72 CREP wetlands have been restored or are under development in Iowa, Richmond said.
Dean Lemke, also with IDALS, said the wetlands should be able to be used for flood control and retention.
Laura Christianson, an ISU graduate student, shared information on the research farm's bioreactor, which is located on the edge of a field. A bioreactor is an excavated trench filled with woodchips. Geo textile material covers the wood chips. Soil seeded to grass is on top. A water control structure diverts tile water into the bioreactor where denitrifying bacteria reduces the nitrate concentration of the water.
Research shows bioreactors can remove up to 55 percent of nitrate in tile line water, although removal at the research farm is just 12 percent for the two years samples have been taken, Christianson said.