|Smith Jr, Sammie|
Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2005
Publication Date: 11/1/2006
Citation: Cullum, R.F., Knight, S.S., Cooper, C.M., Smith Jr, S. 2006. Combined effects of best management practices on water quality in oxbow lakes from agricultural watersheds. Soil & Tillage Research. Elsevier Science Publishers B.V. doi:10.1016/j.still.2005.09.004, Amsterdam, Netherlands. 90:212-221. Available online at www.sciencedirect.com. Interpretive Summary: Recreational resources of oxbow lakes in the Mississippi Delta have decreased as water quality and fisheries have declined. Three watersheds with oxbow lakes were selected and developed with different levels of best management practices (BMPs) in an attempt to improve water quality for fish production. Water quality within the lakes was examined from before and after best management practices. Analyses of water quality prior to the implementation of BMPs indicated lakes that were ecologicaly stressed due to excessive in-flowing sediments. The most dramatic improvements in water quality were realized through the use of conservation tillage, winter cover crops, and grade control BMPs. Sediments were decreased while water clarity and chlorophyll increased. Reducing suspended sediment concentrations in these oxbow lakes resulted in conditions favorable for improved fish productivity. These results will be useful to extension personnel, action agencies involved in water quality planning, and to farmers.
Technical Abstract: Water quality conditions in three oxbow lakes were examined before and after best management practices (BMPs) implementation within the Mississippi Delta. Experimental design called for the development of structural and cultural treatments to reduce sediment and associated pollutants entering watershed oxbow lakes. Three watersheds were selected and developed with different levels of BMPs. Changes in lake water quality were used as measures of management success. Analyses of water quality data prior to the implementation of BMPs suggested the lakes were stressed and ecologically damaged due to excessive sediments. Significant improvements in water quality were observed with the use of cultural and structural BMPs. Sediments decreased 34 to 59%, while Secchi visibility and chlorophyll generally increased. The most dramatic improvements in water quality occurred in the two watersheds that featured cultural practices and combinations of cultural and structural practices. Reducing suspended sediment concentrations in these oxbow lakes favored phytoplankton production resulting in increased chlorophyll concentrations and higher concentrations of dissolved oxygen. Results further indicated that cultural BMPs may play the more vital role in improving lake water quality and are needed in addition to structural measures to ensure improved water quality in oxbow lakes receving agricultural runoff.