DGS04-9 New Jersey water withdrawals, transfers, and discharges by Watershed Management Area, 1990-1999

Abstract

This product is an Excel workbook (called WMATRANSFERS25.XLS) which documents fresh-water withdrawals, fresh-water transfers, sewage transfers, and reclaimed-water discharges in New Jersey on a Watershed Management Areas basis. It also presents withdrawals and discharges on a statewide basis. Monthly data are stored by HUC14 watershed in the underlying data base for a ten-year period from 1990 to 1999. In order to minimize locational errors of water and sewer service areas the data are summarized here on an annual and monthly basis by watershed management area.

Withdrawal and use data are presented for potable, commercial, industrial, agricultural, and power-generation uses of more than 100,000 gallons of water a day. This is the cutoff volume for regulation by the N.J. Department of Environmental Protection (NJDEP), Bureau of Water Allocation (BWA). Withdrawals are broken out into the source of the water (surface water or ground water), where the water is withdrawn, and where the water is transferred for end use. An estimate of fresh-water withdrawals by domestic wells is included in the analysis.

Ground-water withdrawals are broken out by aquifer group on both a WMA and statewide basis. This includes an estimate of private, domestic-well water withdrawals. Withdrawals for domestic use are assumed to be partially consumed (evaporated) with the remainder discharged to the ground in the same location as the water was withdrawn.

Agricultural water use is broken out by a detailed agricultural use type on both a WMA and statewide basis. The volume of water consumed by each detailed agricultural use type is also given. Nonconsumptive water use by agricultural is assumed to be discharged in the same location as the water was withdrawn.

Water transfers for drinking-water service areas are linked to the sources of water in order to track movement of potable water using multiple NJDEP databases. A geographic information system (GIS) was used to overlay sewer service areas with drinking-water service areas. The sewer service areas are then linked to discharge points of reclaimed water. This allows for tracking of water from the area of use to a discharge point.

This report summarizes fresh-water withdrawals, fresh-water transfers, water use, sewage transfers, and reclaimed-water transfers on a watershed basis. The accuracy of the results depends on the accuracy of withdrawal locations and on GIS coverages of water-purveyor service areas and sewer service areas. The best available coverages were used but inaccuracies still exist. It is hoped that by summarizing on a HUC11 level or larger scale, that errors arising from inaccuracies in service area coverages will diminish in relative magnitude to other components of the water budget at that scale.

Each type of water use is assigned a monthly consumptive-use percentage. This estimates the percent of water that is lost to the atmosphere through evaporation by that water use in that month. This allows for an estimation of total consumptive water use in each watershed management area, by use type.

Water use is reported in each WMA. This is not equivalent to water withdrawals in each WMA because of the volumes of exports and imports.

HUC11 (Hydrologic Unit Code) watersheds are defined by the United States Geological Survey. There are 151 HUC11 watersheds in New Jersey ranging from 3 to 349 square miles in size, with an average 59 square miles. Each HUC11 incorporates a number of HUC14s subwatersheds. A number of contiguous HUC11 watersheds comprise a HUC8 cataloging unit watershed. New Jersey is divided into twenty watershed management areas and five water regions. These are defined by the NJ Department of Environmental Protection as a way to assist in managing the State’s resources. Water withdrawals and transfers are quantified internally on a detailed watershed basis (HUC14) but are reported here on a WMA basis.

These data are stored in the New Jersey Water Tracking Data Model (NJWaTr) (Tessler, 2003). The underlying model was populated with data by the New Jersey Geological Survey.

This product is in support of an update of New Jersey’s Water Supply Plan. The plan is updated on a periodic basis in order to ensure an adequate and safe supply of water for New Jersey. Later products of the water supply plan will address these components as well as a total water budget for each HUC11.

Due to a ongoing data-accuracy evaluation process this product is considered more accurate than earlier reports.