Water Resources Research Act Program

Details for Project ID 2006GA110B

Characterizing Nutrient Releases from Southeastern Piedmont Lake Sediments

Institute: Georgia
Year Established: 2006 Start Date: 2006-03-01 End Date: 2007-02-28
Total Federal Funds: $18,000 Total Non-Federal Funds: $36,000

Principal Investigators: Todd Rasmussen, Bruce Beck, William Miller

Project Summary: Controlling lake eutrophication is a major objective of current management efforts in North Georgia, a rapidly urbanizing region in the Southeastern United States. Monitoring programs have shown that watershed loading to reservoirs is the primary source of lake eutrophication. These wide-ranging monitoring studies include the USGS NAWQA study of the Apalachicola-Flint-Chattahoochee river system, as well as local- and EPA-funded studies of the Lake Lanier watershed, a major water-supply reservoir of the Atlanta metropolitan area, along with additional recent and ongoing monitoring programs in the Lake Allatoona watershed, another major water-supply watershed affected by rapid urbanization within the Atlanta area. To reduce and prevent the eutrophication of these important water resources, recent regulatory controls for nutrients have been established as part of the Clean Lakes program and court-ordered TMDLs. These regulatory efforts justifiably focus on the reduction and minimization of watershed nutrient inputs, primarily phosphorus, into lake systems. Watershed reductions in phosphorus loading are expected to improve lake water quality because phosphorus is widely believed to be the limiting nutrient for phytoplankton growth. An additional source of nutrients to lake foodwebs is the release from lake sediments. Because many nutrients, including phosphorus, nitrogen, and carbon, are abundant in lake sediments, the release from benthic sediments can be a significant additional cause of phytoplankton growth. Deposition of sediments in lakes is an ongoing, storm-driven process, which is exacerbated by increasing watershed urbanization. This study focuses on the characterization and control of sediment nutrient releases within Southeastern Piedmont lakes. There are three components to this study; 1) Column studies of phytoplankton abundance in lake water overlying sediments to evaluate the effects of sediment anoxia, elevated pH, sediment re-suspension and mixing, and removal of larger sediments, 2) Sediment batch tests to characterize nutrient sorption and desorption (i.e., isotherms), and 3) Estimation of the relative importance sediment release vs. watershed loading on phytoplankton growth.