Invasive Aquatic Plant Expansion in Walter F. George Lake

Proceedings of the 2007 Georgia Water Resources Conference, March 27-29, 2007, Athens, Georgia.Walter F. George Lake, a large multipurpose reservoir on the Chattahoochee River, is operated by the U.S. Army Corps of Engineers (Corps) for the primary purposes of navigation and hydropower, and secondary purposes of recreation, regulation of stream flow, and fish and wildlife conservation. The lake has not historically had problems with invasive aquatic plants. Hydrilla (Hydrilla verticillata), an invasive non-native species, was first discovered on the lake in 1991 at the East Bank Public Use Area. This plant spread slowly for several years, but in 2002 several new infestations were identified on the lake. Herbicidal treatments have proved to be expensive and largely ineffective in reducing the rapid expansion of hydrilla and other invasive species. Annual interagency surveys have revealed that invasive nuisance aquatic plants are now well established and expanding within the lake, with hydrilla found on approximately 2,400 acres in the 2006 survey. A comprehensive management plan is being developed by the Corps to address aquatic vegetation management issues on the lake and the Corps is coordinating with appropriate Federal and State agencies, as well as local stakeholders, on development of this plan. The plan will delineate existing vegetation levels; develop an estimate for reasonable spread of aquatic plants within the lake based on reservoir/water conditions and plant biology; identify management objectives; evaluate management options and resource impacts (including no action); select best plan; describe implementation strategy, and define monitoring plan. The plan will include adequate public and agency involvement/input, as well as preparation of an Environmental Assessment. At this stage in the plan development, the Corps believes the best option is to manage hydrilla by the introduction of the triploid (sterile) grass carp (Ctenopharyngoden idella). The proposed action is to introduce the grass carp at a relatively low stocking rate into the lake at areas of high hydrilla concentration since the hydrilla infestation is a relatively small percentage of the lake at this time. Delays in implementation of this action would miss a “window of opportunity” and significantly increase the management cost and reduce the likelihood of successful control of this invasive species.Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, Natural Resources Conservation Service, The University of Georgia, Georgia State University, Georgia Institute of TechnologyThis book was published by the Institute of Ecology, The University of Georgia, Athens, Georgia 30602-2202. The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of The University of Georgia, the U.S. Geological Survey, the Georgia Water Research Institute as authorized by the Water Resources Research Act of 1990 (P.L. 101-397) or the other conference sponsors