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Vol. 7

No. 1

Summer 1999

A Newsletter About New Jersey's Water Quality Programs

Water Usage Declines in New Jersey
by Jeffrey Hoffman, New Jersey Geological Survey

Water usage data reported to the DEP shows that New Jersey is using less water. Between 1990 and 1996, total withdrawals have decreased from 1,037 billion gallons (bg) to 877 bg. Withdrawals for potable supply (domestic use), the greatest demand of water in New Jersey, have ranged from 418 bg to 452 bg, with an average of 436 bg. Most of the overall decline in water withdrawals is due to a drop in the volume of water used for power generation, from 430 bg in 1990 to 301 bg in 1996. (Water used for power generation may or may not be nonconsumptive depending on exactly how it is used.) The remaining uses of water (for industrial, agricultural, mining, non-agricultural and commercial uses) have ranged between 164 and 196 bg. Average withdrawals for these uses have been: industrial - 94 bg; agricultural - 49 bg; mining - 33 bg; non-agricultural irrigation - 3 bg; and commercial - 0.5 bg.

These data are based on use volumes reported to the Bureau of Water Allocation in the Water Supply Element. This Bureau is responsible for regulating all water users who withdraw more than 100,000 gallons per day.

On average, 75% of total water withdrawals and 59% of potable water withdrawals are from surface water. The relative importance of ground and surface water as a source of potable water varies by county. Ground water supplied 100% of the potable water physically withdrawn in Camden, Cape May, Cumberland, Gloucester, Hudson and Warren Counties during period from 1990-96. In contrast, ground water supplies only 4% of potable water withdrawn in Passaic County. These numbers are not always indicative of the source of water actually consumed in each county. For example, most of the surface water withdrawn in Passaic County is exported to Hudson and Bergen Counties.

Table 1 below presents the average total and potable withdrawals, by county, over the period 1990-1996, in millions of gallons. This table shows only where water is withdrawn—it does not identify where the water is used. Thus, it does not identify which counties are net importers or exporters of water.

Total withdrawals in New Jersey correspond to approximately 15% of rainfall, on a statewide average. Withdrawals for potable use are between 5% and 8% of precipitation. Withdrawals for potable use, irrigation, and agriculture show a strong seasonal correlation with precipitation during the growing season. This is because water is withdrawn for irrigation during the growing season when rainfall is needed more.

These data will be reported in more detail in a forthcoming publication from the New Jersey Geological Survey. Withdrawal values for 1995 are currently available on the Survey’s web page at www.state.nj.us/dep/njgs/enviroed/index.htm.

Table 1. Total and average withdrawals by county,
1990-1996, in millions of gallons.

CountyAverage total withdrawals, 1990-96Average potable withdrawals, 1990-96
 SourceTotalSourceTotal
 surface waterground water surface waterground water 
 mg%mg% mg%mg% 
Atlantic1,2206.9%16,51593.1%17,7353863.0%12,63797.0%13,023
Bergen50,09582.6%10,58717.4%60,68249,34184.0%9,40016.0%58,741
Burlington47,57062.4%28,66837.6%76,2381,4258.2%15,93791.8%17,362
Camden1,4505.5%24,86894.5%26,31800.0%24,135100.0%24,135
           
Cape May8259.4%7,97290.6%8,79700.0%5,884100.0%5,884
Cumberland19,21055.6%15,35844.4%34,56900.0%7,542100.0%7,542
Essex3,68827.8%9,56272.2%13,2503,64228.7%9,05771.3%12,700
Gloucester19,13557.7%14,03542.3%33,17000.0%9,406100.0%9,406
           
Hudson00.0%205100.0%20501.2%498.8%4
Hunterdon48,36190.8%4,8879.2%53,24831,79389.6%3,69010.4%35,483
Mercer190,39297.6%4,6092.4%195,00111,60573.2%4,25926.8%15,863
Middlesex7623.7%19,57396.3%20,3355664.1%13,19495.9%13,760
           
Monmouth18,26766.4%9,25833.6%27,52517,66967.3%8,56932.7%26,239
Morris18,93947.1%21,29952.9%40,23818,46649.8%18,63650.2%37,102
Ocean2,0358.7%21,40191.3%23,4361,3406.9%18,22093.1%19,561
Passaic180,33498.3%3,1871.7%183,52279,34196.3%3,0183.7%82,359
           
Salem6,87460.4%4,50539.6%11,37949518.3%2,20681.7%2,700
Somerset38,59692.9%2,9317.1%41,52738,51794.4%2,3045.6%40,821
Sussex5938.7%6,22091.3%6,81354612.5%3,81087.5%4,356
Union4,78246.0%5,61054.0%10,3911,82531.9%3,89168.1%5,715
Warren73,81891.0%7,3079.0%81,125150.4%3,29299.6% 3,306
           
Yearly total:726,94575.3%238,55724.7%965,502256,97258.9%179,09041.1%436,063

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Last revision Tuesday, June 22, 1999