Bathymetry of Groundhog and Totten Reservoirs

Science Center Objects

In order to better characterize the water supply capacity of Groundhog Reservoir, Dolores County, Colorado, and Totten Reservoir, Montezuma County, Colorado, the U.S. Geological Survey, in cooperation with the Dolores Water Conservancy District, conducted a bathymetric survey of Groundhog and Totten Reservoir. The study was performed in June 2011 using a man-operated boat-mounted multibeam echo sounder integrated with a global positioning system and a terrestrial real-time kinematic global positioning system. Two datasets were collected for each reservoir and were merged and imported into geographic information system software. A bathymetric map of each reservoir was generated in addition to plots for the stage-area and the stage-volume relations.

BACKGROUND:

Satellite view of Groundhog Reservoir

Satellite view of Groundhog Reservoir

Credit: Google

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.

OBJECTIVES:

Boat at Groundhog Reservoir in Colorado

Looking north-northeast at Groundhog Reservoir with boat equipped with GPS and a multibeam echo sounder in the foreground and Lone Cone in the background; photo taken from the west shore of Groundhog Reservoir.

  1. Perform a bathymetric survey below the water level of the reservoir using a man-operated boat-mounted multibeam echo sounder integrated with a global positioning system.
  2. Perform a terrestrial topographic survey above the water level to the top of dam plus two to three feet using a terrestrial real-time kinematic global positioning system.
  3. Survey the principal outlet and spillway invert locations and elevations.
  4. Merge the two collected datasets, the bathymetric survey and the terrestrial topographic survey, and import into geographic information system software.
  5. Produce a bathymetric map of each reservoir present with plots and tables of stage-surface area and stage-storage.