The 2001 Lake Mead Bathymetry Study

Lower Colorado Regional Office GIS Group

The Bureau of Reclamation (Reclamation) surveyed Lake Mead Reservoir in 2001 in order to develop a present day storage-elevation relationships. The major objective of the field collection was to map the areas of sediment accumulation since closure of Hoover Dam in February of 1935. The primary objective for conducting the reservoir survey was to measure the current reservoir area-capacity. The collected data can also be used to determine: storage depletion caused by sediment deposition since closure of the dam annual sediment yield rates current location of sediment deposition current reservoir topography economic life of the reservoir Previous sedimentation surveys of Lake Mead completed in 1948-49 and 1963-64, utilized the range line collection method. The 1963-64 survey generated new reservoir topography from range lines that were collected from 300 to 400 meters apart. Results of these collections measured the vast majority of the sediments as a flat bottom deposit within the original river channel geometry. A 1999 University of Nevada and USGS sidescan sonar survey of the lower portion of Lake Mead found the accumulation of sediments to be restricted to the original river beds of the Colorado River and Las Vegas Creek and also to be flat-lying. This situation was also found during the 1986 Lake Powell survey that measured the majority of sediment deposits within the original channel geometry and to be flat in nature. Utilizing these previous survey results, and working within the available budget for conducting the Lake Mead survey, the 2001 collection focus the measurements around the original river channel areas.