CONSERVATION EFFECTS ASSESSMENT FOR THE ST. JOSEPH RIVER WATERSHED
Location: National Soil Erosion Research Lab
Title: Assessing Conservation Effects on Water Quality in the St. Joseph River Watershed
Submitted to: Agro-Environment Symposium
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 2008
Publication Date: May 27, 2008
Citation: Flanagan, D.C., Huang, C., Pappas, E.A., Smith, D.R., Heathman, G.C. 2008. Assessing Conservation Effects on Water Quality in the St. Joseph River Watershed. In: Proceedings of the Agro-Environment Symposium, April 28-May 1, 2008, Antalya, Turkey. 2008 CDROM.
Agriculture is a major contributor to non-point source pollution of streams, rivers and lakes in the United States. In particular, pesticides applied for agricultural crop production can move off-site in runoff and drainage waters, and reach surface drinking water sources. In the northeastern part of the state of Indiana, the herbicide atrazine has been found in the drinking water of the city of Ft. Wayne (population ~200,000). The St. Joseph River is the water source, and its watershed extends north and east into major cropland areas. The Cedar Creek Watershed (CCW) is the largest sub-catchment, and is where we have focused our research. A Source Water Protection Initiative project in the CCW was begun in 2002, with the initial focus to evaluate existing and innovative agricultural practices on reducing pesticide losses to the River (particularly atrazine). Subsequently, this effort then became a part of the US Department of Agriculture’s nationwide Conservation Effects Assessment Project (CEAP) with the focus expanded to include nutrients and sediment as water quality concerns. The CCW encompasses about 707 km2, and topography is flat to gently rolling, with many depressional areas. Large amounts of surface runoff water enter surface tile inlets in these “pot-hole” depressions, so understanding and managing these inlets may be of critical importance here. A series of deep man-made drainage ditches (some as deep as 8 m) were created throughout this region about 100 years ago to remove excess water, and allow farming operations. Soils here are mostly silt loams, silty clay loams, and clay loams, and subsurface tile drainage is utilized in many fields to also improve drainage and agricultural production. The current project includes a range of research, monitoring, and modeling efforts. In the CCW, monitoring is currently being conducted on 12 catchments ranging from 2 to 19,000 hectares. At the smallest field scale, a pair of sites allows direct comparisons between the effects of conventional and no-till farming practices on runoff, sediment, nutrient, and pesticide losses. Another pair of small field monitors at a depression site allows examination of the impacts of surface tile inlets and/or blind inlet drains and associated management practices on water quality there. Eight sampling sites on three sets of larger nested watersheds monitor runoff, nutrients and pesticide losses in the large drainage ditches and in Cedar Creek itself. A network of automated weather stations and soil moisture sensors has been deployed to provide detailed information on the complete hydrologic cycle in the watershed. Laboratory flume studies as well as field rainfall simulation experiments have also been conducted to expand our knowledge of the pesticide and nutrient transport processes. Watershed water quality model calibration and validation utilizing the SWAT (Soil and Water Assessment Tool) and AnnAGNPS (Annualized AGricultural Non-Point Source pollution model) models have been conducted as well. This presentation will present results from the past six years, and discuss what we have learned during that time. Many challenges still exist to allow evaluation of the true impacts of conservation practices on water quality.