Bathymetry of New York City's West of Hudson Reservoirs

Science Center Objects

Background Every day, the New York City Department of Environmental Protection (DEP) supplies more than one billion gallons of drinking water to more than nine million people. To do this, the DEP maintains an extensive network of reservoirs and aqueducts. A major part of this system, the West of Hudson (WOH) network, in the Delaware and Hudson River drainages, includes six reservoirs (fig. 1...

 

Background

Every day, the New York City Department of Environmental Protection (DEP) supplies more than one billion gallons of drinking water to more than nine million people. To do this, the DEP maintains an extensive network of reservoirs and aqueducts. A major part of this system, the West of Hudson (WOH) network, in the Delaware and Hudson River drainages, includes six reservoirs (fig. 1) – Ashokan, Cannonsville, Neversink, Pepacton, Rondout, and Schoharie – which were constructed from the early 1900s to the 1960s and have an estimated combined storage capacity of more than 460 billion gallons.

 Problem and Objective

The daily and seasonal management of the WOH reservoirs by DEP depends on accurate bathymetric data. In the West of Hudson reservoirs, these data are used to monitor and regulate storage capacity, to model water quality, and to plan future operations. The bathymetry of the reservoirs was initially determined from land surface maps before the reservoirs were built, 50 to 100 years ago.

The objective of this project is to provide updated bathymetric data needed to help better manage water use and availability in the watersheds of the six WOH reservoirs.  The information provided as part of this study will help DEP to improve water-quality models used in reservoir management and to more accurately regulate storage in the reservoirs, to better provide quality drinking water to its many customers.

Approach

Depth data will be collected from a small boat using a single beam echosounder, generally following the procedures documented in Wilson and Richards (2006). Locations of measured depths will be determined using real-time kinematic (RTK) GPS.  Depth data will be collected along transects laid out perpendicular to the long axis of the reservoir; additional transects that cross the main transects will be used for quality assurance. Total transect lengths will be approximately 120 to 380 kilometers per reservoir, and approximately 1,400 km overall. Position and depth data will be imported into a geographic information system (GIS) database to generate a triangulated irregular network model (TIN) to approximate the surface of the reservoir bottom. The raw TIN will be edited to ensure proper representation of hydrologic features such as ridges, valleys, and steep slopes. The edited TIN will be used to create contour maps and stage-area-capacity tables.

Report

Bathymetry of Ashokan, Cannonsville, Neversink, Pepacton, Rondout, and Schoharie Reservoirs, New York, 2013–15

Related Links

Current NYC Reservoir Levels: http://www.nyc.gov/html/dep/html/drinking_water/maplevels_wide.shtml

Related Publications

Hittle, C.D., and Ruby, A.T., III, 2008, Bathymetric surveys of Lake Arthur and Raccoon Lake, Pennsylvania, June 2007: U.S. Geological Survey Data Series 357, 10 p. http://pubs.usgs.gov/ds/357/

Langland, M.J., 2009, Bathymetry and sediment-storage capacity change in three reservoirs on the Lower Susquehanna River, 1996–2008: U.S. Geological Survey Scientific Investigations Report 2009-5110, 21 p. http://pubs.usgs.gov/sir/2009/5110/

Sekellick, A.J., and Banks, W.S.L., 2010, Water volume and sediment accumulation in Lake Linganore, Frederick County, Maryland, 2009: U.S. Geological Survey Scientific Investigations Report 2010–5174, 14 p. http://pubs.usgs.gov/sir/2010/5174/

Wilson, G.L., and Richards, J.M., 2006, Procedural Documentation and Accuracy Assessment of Bathymetric Maps and Area/Capacity Tables for Small Reservoirs: U.S. Geological Survey Scientific Investigations Report 2006–5208, 24 p. plus oversize figs. http://pubs.usgs.gov/sir/2006/5208/

Wilson, G.L., and Richards, J.M., 2008, Differences in reservoir bathymetry, area, and capacity between December 20–22, 2005, and June 16–19, 2008, for lower Taum Sauk Reservoir, Reynolds County, Missouri: U.S. Geological Survey Scientific Investigations Map 3061, 1 sheet. http://pubs.usgs.gov/sim/3061/

Project
Location by County

Delaware
County, NY, Greene County, NY, Schoharie County, NY, Sullivan County, NY,
Ulster County, NY