Delaware River Basin Focus Area Study: Water Use

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Water-use data were compiled or estimated for 8-digit and 12-digit Hydrologic Unit Code watersheds for 2010. Water withdrawal, interbasin transfers, return flow, and hydroelectric power generation release data were compiled for 11 water-use categories.

National Water Census  •  Delaware River Basin  •  Process-Based Streamflow  •  Statistical Streamflow  •  Water Use  •  Ecological Flow

 

Instream and offstream water use was calculated for 2010 for the Delaware River Basin based on information received from Delaware, New Jersey, New York, and Pennsylvania. Water withdrawal, interbasin transfers, return flow, and hydroelectric power generation release data were compiled for 11 categories by hydrologic subregion, basin, subbasin, and subwatershed. Data availability varied by state.

The Focus Area Study examined water use at a finer level of detail than had been done previously, estimating water withdrawals and returns for 426 subwatersheds (HUC-12) compared to 13 subbasins (HUC-8) in prior water-use compilations. Site-specific data were used whenever possible to calculate public supply, irrigation (golf courses, nurseries, sod farms, and crops), aquaculture, self-supplied industrial, commercial, mining, thermoelectric, and hydroelectric power withdrawals. Where site-specific data were not available, primarily for crop irrigation, livestock, and domestic use, various techniques were used to estimate water withdrawals incorporating ancillary information such as Census populations, estimates of population served by public suppliers by county, the U.S. Department of Agriculture Cropland Data Layer, and estimates of livestock water use by county based on U.S. Department of Agriculture, National Agricultural Statistics Service data.

Withdrawals are generally highest in the southern half of the basin, where most of the population lives, but they can also be high in the north due to out-of-basin transfers as shown on the map of public-supply withdrawals. Ninety-four percent of the water withdrawals in New York are transferred out of the basin to supply New York City with drinking water. An estimated 14.7 million people relied on drinking water withdrawn in the Delaware River Basin for their household use; over 8 million people outside of the Basin (in New York City and New Jersey) and 6.7 million people within the Basin.

Public Supply Water Withdrawls, Transfers, and Use by Source, Subbasin,and Subwatershed in the Delaware River Basin, 2010

Public supply water withdrawals, transfers, and use by source, subbasin, and subwatershed in the Delaware River Basin, 2010

Key Findings and Results

  • Total water withdrawals for 2010 were about 7,130 million gallons per day (Mgal/d). Freshwater withdrawals were about 58 percent of the total and the remaining 42 percent was from saline water.
  • Surface-water withdrawals were 92 percent of the total; about 54 percent of surface water withdrawn was freshwater.
  • Thermoelectric power generation represented 69 percent of total withdrawals and 47 percent of all freshwater withdrawals.
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National Water Census  •  Delaware River Basin  •  Process-Based Streamflow  •  Statistical Streamflow  •  Water Use  •  Ecological Flow