Water quality in Beasley Lake, an oxbow of the Sunflower River in the Mississippi Delta, USA, has been assessed biweekly since 1996.  Although the lake is surrounded by production agriculture, different conservation practices have been installed and monitored within the watershed over the last 25 years, resulting in decreases of suspended sediment and nutrient concentrations within the lake. Specifically, suspended sediment concentrations have decreased by more than 60% and water clarity has increased more than 100% during the 25-year period.  Concentrations of total phosphorus have been reduced 50-70% within the lake, and nitrate-nitrogen concentrations have been reduced by 80%.  Total nitrogen concentrations within the lake, however, have not decreased.  Current studies focus on within-lake nutrient cycling, management of harmful algal blooms, and the effect of legacy nutrients on lake water quality.  Recent assessments suggest the annual release of ammonium and orthophosphate from lake sediments and nitrogen fixation may contribute to observed lag in water quality response following implementation of conservation practices. This unique long-term lake water quality assessment is providing valuable decision tools for landowners, farmers, and conservationists on implementation of conservation practices and their anticipated benefit to water quality.

Primary Presenter: Matt Moore, USDA Agricultural Research Service (matt.moore@usda.gov)

Authors:

Matthew Moore, USDA Agricultural Research Service  (matt.moore@usda.gov)

Richard Lizotte, Jr., USDA Agricultural Research Service  (richard.lizotte@usda.gov)

Jason Taylor, USDA Agricultural Research Service  (jason.taylor@usda.gov)

Lindsey Witthaus, USDA Agricultural Research Service  (lindsey.witthaus@usda.gov)

Rachel DuBose, US Geological Survey  (rachel.dubose@usgs.gov)

Stephen DeVilbiss, USDA Agricultural Research Service  (stephen.devilbiss@usda.gov)

Martin Locke, USDA Agricultural Research Service  (martin.locke@usda.gov)

Lucas Heintzman, USDA Agricultural Research Service  (lucas.heintzman@usda.gov)