Management and development of aquatic habitat in agricultural drainage systems

Drainage improvements in agricultural watersheds have extensively modified midwestern streams and rivers and the flora and fauna associated with these water resources. The alteration of low order streams in Central Illinois has been particularly severe. This study is designed to support better management of these agricultural drainage systems through an improved understanding of the type and quantity of habitat required for maintenance of high quality fisheries and aquatic resources. Fisheries resources in two watersheds, the Middlefork and Vermilion River in northeastern Champaign county were evaluated. The potential for a high quality fisheries was demonstrated. Additional analyses involved the assessment of habitat conditions in these basins with the objective of identifying modifications of existing drainage district maintenance procedures which would enhance environmental quality and fishery potential while meeting engineering requirements for channel hydraulic capacity, and flood stage elevation and duration. Three management options were evaluated: 1) maintenance of riparian vegetation, 2) development of instream cover as a habitat enhancement, and 3) increasing the number and depth of pools. The preferred option, considering both fish species habitat needs and impact on existing drainage district maintenance practices, was increasing the number and depth of pools. Although an increase in instream cover would be expected to improved fisheries habitat, the expected hydraulic consequences may limit the application of this option. Maintenance of riparian vegetation would be expected to provide positive benefits to fisheries, but the improvement in overall habitat quality is more strongly related to instream habitat modifications.U.S. Department of the InteriorU.S. Geological SurveyOpe