ADVANCING SOIL AND WATER CONSERVATION THROUGH A WATERSHED DIAGNOSTIC STUDY OF THE MIDDLE MISSISSINEWA RIVER, EAST-CENTRAL INDIANA

Stream conditions were assessed for eleven sub-watersheds of the highly-agricultural middle Mississinewa River watershed following the IDNR Lake and River Enhancement watershed diagnostic protocol. Required assessments included chemistry for nine parameters at low-flow and high-flow, biological quality by macroinvertebrate Pollution Tolerance Rating, physical habitat by the Qualitative Habitat Evaluation Index, and simple modeling for sediment and nutrient loading by the Export Coefficient Method.

Despite the relatively flat glacial terrain, there are topographic, soil, and land use difference between subwatersheds located on the moraine north of the Mississinewa River compared to those located on the till plain to the south. Additional information collected on watershed morphometrics, such as drainage density and ruggedness, illustrate the landscape differences.

Based on data, the eleven sites were evaluated and ranked for each assessment method and then compiled into a generalized evaluation matrix to identify areas of primary and multiple impairments. Subsequent field studies have verified many of the conclusions of the diagnostic study, including elevated sediment load in several subwatersheds, excessive E coli in some, and high nutrient loads in others.

Generalized land treatment practices to address the soil and water quality issues can be recommended by the assessments, however, additional detailed evaluation will be required for identification of specific land treatments and locations. For example, additional fluvial erosion hazard assessments will be conducted to refine specific sites and practices of stream stabilization. Once identified, assistance from soil and water agencies will facilitate voluntary participation in a variety of federal cost-share conservation programs in the targeted areas of critical concern.