Elevation Contours, West Basin of Ashokan Reservoir, 2013 to 2014

From 2013 to 2015, bathymetric surveys of New York City’s six West of Hudson reservoirs (Ashokan, Cannonsville, Neversink, Pepacton, Rondout, and Schoharie) were performed to provide updated capacity tables and bathymetric maps. Depths were surveyed with a single-beam echo sounder and real-time kinematic global positioning system (RTK-GPS) along planned transects at predetermined intervals for each reservoir. A separate set of echo sounder data was collected along transects at oblique angles to the main transects for accuracy assessment. Field survey data was combined with water-surface elevations in a geographic information system to create three-dimensional surfaces representing reservoir-bed elevations in the form of triangulated [...]