Submitted to: Mississippi Water Resources Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/1/1998
Publication Date: N/A
Interpretive Summary: Best management practices are being used in the Management Systems Evaluation Area (MSEA) project in the Mississippi Delta to reduce erosion and pollution from cotton fields. This study examined and documented water quality conditions on three oxbow lakes before the introduction of practices. Analyses of water quality showed that the oxbow lakes were stressed and ecologically damaged because of too much sediment. The amount of sediments in the lake water was higher than that of lakes sampled in the same area in 1969. The sediments blocked sunlight from plankton, which is the first link in the food chain. If sediments can be reduced in these oxbow lakes by using best management practices, fish habitat should improve. This research is the first effect that shows the direct effects of land and farm management practices designed to improve lake ecology.
Technical Abstract: The Mississippi Delta MSEA (Management Systems Evaluation Area)is a competitive agricultural systems-based research project designed to address the problems associated with non-point source pollutants. Changes in lake water quality are being to test the effects of land and cultural treatments targeted to reduce sediment and other pollutants entering ox-bow lakes. Analyses of water quality prior to the implementation of management practices indicate lakes that were stressed and ecologically damaged due to excessive in-flowing sediment. Mean total water column sediment concentrations ranged from 487 mg/L to 334 mg/L with maximum values reaching 2365 mg/L for Beasley Lake, 1094 mg/L for Thighman Lake and 804 mg/L for Deep Hollow Lake. High suspended solid concentrations on Thighman and Beasley Lakes corresponded to lower concentrations of chlorophyll. Deep Hollow Lake had the highest mean concentration of chlorophyll at 24.42 mg/L as well as the lowest mean concentration of suspended sediment (269 mg/L). Temperature and pH values fell within ranges expected for the oxbow lakes in the Mississippi Delta; however, all three lakes experienced periods of low dissolved oxygen. Reducing suspended sediments should provide conditions favorable for phytoplankton production. Increases in phytoplankton will result in increased chlorophyll concentrations and higher concentrations of dissolved oxygen, leading to improved secondary productivity. Land and farm management practices designed to control erosion and reduce transport of soil, organic matter and agricultural chemicals should improve water quality and therefore ecological conditions.