Agricultural Impacts On Seasonal Trend In Pollutant Concentration In Lake St. Joseph Watershed, Northeast Louisiana.

It is widely noted that most water bodies located in intense agricultural areas are often impaired, primarily due to runoff of pollutants from nearby agricultural fields.  In Louisiana, pollutant discharge from irrigated and non-irrigated crop production are among the leading causes of water quality impairment, particularly in rivers and lakes as reported in the 2010 Louisiana water quality inventory. Lake St. Joseph is an oxbow lake in the Ouachita River Basin in northern Louisiana, originally formed by the Mississippi River. Within this watershed, cotton, corn and soybean productions account for close to 60% of the agricultural land use, while forest hardwood and pasture account for 22% and 12%, respectively. Hence, the lake has been reportedly impaired, with low dissolved oxygen (DO), nutrients (particularly nitrogen (N) and phosphorus (P)), suspended solids and pesticides cited as the major causes of impairment, while runoff from agricultural fields has been documented as the major source.  This study is intended to evaluate the seasonal trend in pollutant concentration in the lake system as related to agricultural activities within this watershed. Water quality monitoring will be conducted at 3 strategic locations within the lake, and also at 3 inflow ditches and 1 major outflow ditch. The seasonal trend of key water quality indicators such as nutrients (N and P), turbidity, biochemical oxygen demand, total suspended solids, total dissolved solids, total solids, and anions will be presented.