The Clear Creek Watershed (CCW) includes activities in the upper watershed to reduce flooding and improve water quality, as well as infrastructure projects in the city of Coralville to protect commercial and residential property from flooding.
The Clear Creek Watershed covers 66,132 acres (104 square miles), spanning parts of Iowa and Johnson counties in Southeast Iowa. Clear Creek empties into the Iowa River at Coralville. The watershed lies entirely within the Southern Iowa Drift Plain, comprised of glacial deposits broken up by many small creeks that have molded the landscape into rolling hills and valleys. Abundant rainfall and fertile soils allowed the conversion of the natural prairie and forested landscape to large-scale intensive agriculture, consisting mainly of a corn-soybean rotation. Eighty-four percent of cropland in the upper portions of the watershed is classified as highly erodible. Intensive agriculture on these soils in a moist climate, coupled with stream channelization in the headwaters and increasing urbanization in the lower portions of the watershed, contribute to flash flooding and water-quality degradation after intense spring storms.
The city of Coralville is set along Clear Creek where it joins the Iowa River, leaving it particularly vulnerable to flooding. Recent floods have had a devastating impact on the local economy, causing many businesses to relocate. Unprotected storm sewer discharge points along the creeks and river leave systems vulnerable to backwater. The city determined that it was imperative to construct flood mitigation projects, especially for the existing storm sewer system, to protect businesses and residents from future floods. The Iowa Watershed Approach will provide funding for the city to reconstruct Stormwater Pump Stations (PS) 7 and 8 to the same design level as all other Coralville flood mitigation projects. PS 7 protects about 42.8 acres of developed property, and PS 8 protects about 135.9 acres. This project will benefit every property owner and tenant within these regions.