Iowa's agricultural landscape has long been impacted by excessive nitrogen and other agricultural nutrients in its watersheds. These chemicals pose a threat to wildlife, the environment, and human health. In response, the Iowa Department of Agriculture and Land Stewardship (IDALS) regularly uses the Iowa Conservation Reserve Enhancement Program (CREP) to encourage landowners to voluntarily establish wetlands with the goal of reducing nitrogen loads and limiting the spread of agricultural chemicals into waterways. JEO was hired by IDALS to design a CREP wetland on Des Moines Area Community College (DMACC) property in Dallas County.
The Dallas County wetland is a prime example of how wetlands can remove harmful chemicals from Iowa's watersheds in an efficient and cost-effective way. The wetland's design included a 2.2-acre permanent pool, a sheet pile weir outlet, and a drawdown structure. The wetland intercepts water from the existing 346-acre watershed, including several subsurface drain tiles, which were modified to outlet into the wetland.
The Dallas County wetland project provides many benefits beyond reducing nitrate levels. It also serves as a habitat for local and migratory wildlife, reduces soil erosion, and provides a learning site for future producers and leaders.