Bathymetry of Groundhog and Totten Reservoirs
Study Area: Groundhog Reservoir, Dolores County, Colorado; Totten Reservoir, Montezuma County, Colorado
A better understanding of available water supply aids water managers in their operation of reservoirs during periods of drought and (or) high demand, and, should another bathymetric survey be conducted in the future, provides a dataset that also could be used to determine sedimentation infill rate and the useful lifespan of the reservoir. The U.S. Geological Survey, in cooperation with Dolores Water Conservancy District, carried out bathymetry studies of Totten Reservoir, Montezuma County, Colorado, from June 6–9, 2011 and Groundhog Reservoir, Dolores County, Colorado, from June 27–29, 2011.
The studies were performed using a man-operated boat-mounted multibeam echo sounder integrated with global positioning system navigation and terrestrial real-time kinematic global positioning system. From the real-time kinematic global positioning system surveys, the top of dam at Totten Reservoir was approximately 6,164 feet above North American Vertical Datum 1988 (NAVD 88) and the spillway invert was 6,158 feet above NAVD 88 and at Groundhog Reservoir, the top of dam was approximately 8,738 ft above NAVD 88 and the spillway invert was 8,728 ft above NAVD 88. The two collected datasets from each reservoir were merged and imported into geographic information system software. The results of the studies include a stage-surface area and stage-volume relations and bathymetric maps. At the spillway elevation, the surface area of Totten Reservoir is 244 acres and the volume is 2,990 acre-feet and at the spillway elevation, the surface area of Groundhog Reservoir is 734 acres and the volume is 25,700 acre-feet.