Effectiveness of Conservation Practices in Goodwin Creek and Topashaw Canal Watersheds, Mississippi.

The 2002 Farm Bill provides around $4 billion annually for conservation programs such as Environmental Quality Incentive Program, Conservation Reserve Program, Conservation Security Program, Wetland Reserve Program, Wildlife Habitat Incentives Program, and the Grassland Reserve Program.  The USDA Conservation Effects Assessment Project (CEAP) was developed to quantify the effects of conservation practices from these programs at the watershed scale. To accomplish this objective, data must be compiled on the existing conservation practices (CP) that have been applied in the watershed along with streamflow and water quality during that period. The USDA-ARS National Sedimentation Laboratory has long-term (>25 years) data for the Goodwin Creek watershed (GCW) and a short-term (< 10 year) data on the Topashaw Canal watershed (TCW).  The primary water quality issue in both watersheds is sediment, largely due to gully erosion and stream bank failure. The GCW drains 2,130 ha with 25 raingauges and 7 gauging stations. The TCW covers 11,000 ha and includes six raingages and two stream gauging stations; at the mouth and on Little Topashaw Creek (3,700 ha).  Data have been compiled on the CPs that were employed and stream flow and sediment concentration data. Data for GCW on CPs, rainfall, stream flow and sediment concentrations have shown that changes of crop land to Conservation Reserve Program (CRP) status have caused the total sediment concentration to decrease by 63% over the period of record of the watershed.  TCW data suggest that 54% of the total sediment yield is from gully erosion not counting bank failure.  These databases will allow the assessment of the watershed response to the establishment of CPs and can provide a guide on the value of long-term compared with short-term data.