THE BATHYMETRY AND SEDIMENT ACCUMULATION HISTORY IN LAKE MAUMELLE, CENTRAL ARKANSAS

Lake Maumelle was formed in 1956 when a dam was built on the Big Maumelle River for the purpose of providing drinking water for the city of Little Rock, Arkansas. Today, it is one of two raw water sources that serve the commercial, industrial, and domestic water needs of over 400,000 people. The lake also provides recreational boating and fishing opportunities and habitat for fish and wildlife. Results of studies undertaken between 1990 and 2001 by the USGS indicate that the water quality is nearly undisturbed for the region and that it could remain stable if 1990's conditions are maintained. However, Lake Maumelle is potentially susceptible to water quality degradation due to sediment deposition because of its overall reservoir geometry, increased development within the watershed, and the lake's natural evolution. The purpose of this project is to evaluate sediment deposition taking place in the proximal end of Lake Maumelle where its largest tributary enters. Bathymetry measurements were collected on the west third of the lake using a digital echosounder linked with a Global Positioning System (GPS) on board a 16-foot fishing boat. A Geographic Information Systems (GIS) database was used to compare the results with bathymetry data collected by the United States Geological Survey (USGS) in 1995. The data from this project produced a beneficial up-to-date smoothed bathymetry map. The original course of the Big Maumelle River could clearly be discerned in most of the study area indicating very little infilling of the pre-impoundment topography. When our data was compared to the USGS data, positive correlations existed regarding where sediment deposition is taking place, especially at the westernmost end. In this area of the lake a highway causeway and bridge create a constriction, possibly keeping much of the sediment from entering the rest of the lake. Our results will be a foundation for future research, and be used to help stakeholders protect the quality of Lake Maumelle in anticipation of water supply demands as the region continues to grow.