New Jersey Water Science Center
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Summary of Annual Hydrologic Conditions - 2005
Volume 2: Groundwater
Ground water is one of the Nation’s most important natural resources. It provides about 40 percent of our Nation’s public water supply. Currently, more than one-half of New Jersey’s drinking water is supplied by over 300,000 wells that serve more than 4 million people. (John P. Nawyn, U. S. Geological Survey, written commun., 2004). New Jersey’s population is projected to grow by over a million people by 2030 (U.S.Census Bureau, accessed on the Word Wide Web at www.census.gov on March 2, 2006). As demand for water increases, managing the development and use of the ground-water resource is of paramount importance so that the supply can be maintained for an indefinite time without causing unacceptable environmental, economic, or social consequences.
The U.S. Geological Survey (USGS) has operated a network of observation wells in New Jersey since 1923 for the purpose of monitoring ground-water-level changes throughout the State. Long-term systematic measurement of water levels in observation wells provides the data needed to evaluate changes in the ground-water resource over time. Records of ground-water levels are used to evaluate the effects of climate changes and watersupply development, to develop ground-water models, and to forecast trends.
During 2005, ground-water levels were measured in 214 wells: 159 wells were equipped for continuous
The USGS, in cooperation with the New Jersey Department of Environmental Protection (NJDEP), established a Drought Monitoring Network in 2001. The Drought Monitoring Network, which is one part of the Ground- Water-Level Network, was created to provide data to indicate water-level trends in shallow ground-water systems. Satellite telemetry has been added to 20 wells with continuous recorders in order to make the data available in the shortest time possible. In addition, the frequency of measurements has been increased at 20 additional wells in order to provide better aerial and hydrologic coverage of the hydrologic conditions statewide. The NJDEP drought website can be accessed at www.nj.drought.org.
The USGS Fact Sheet FS-129-02 “Real-Time Ground-Water Level Monitoring in New Jersey” (Jones and others, 2002) describes the ground-water-level satellite telemetry segment of the Drought Monitoring Network in more detail. Historical ground-water data for New Jersey can be accessed on the World Wide Web pages of the USGS at http://waterdata.usgs.gov/nj/nwis/gw. Real-time data from a National Ground Water Climate Response Network, which includes the 20 real-time equipped wells in New Jersey, can be accessed at http://groundwaterwatch.usgs.gov/.
The 45 wells with more than two years of data in which water-levels exceeded their previous measured extremes (highest or lowest water levels) are listed in Table 1. Previous record low water levels were exceeded in 18 of the 214 wells in the statewide observation-well network during the 2005 water year. Fourteen of the record low water levels were in wells located in the Coastal Plain; four were in the northern part of the State. Ten of these record low levels were the result of increasing withdrawals from wells that tap two confined aquifers-- the Atlantic City 800- foot sand of the Kirkwood Formation and the Piney Point aquifer in the southern part of the State. Previous record high water levels were exceeded in 27 network observation wells during the 2005 water year.
New Jersey’s average annual precipitation ranges from about 40 inches along the southeastern coast to 51
inches in the north-central part of the State. Statewide, the annual mean precipitation is 47.2 inches per water year
based on precipitation during 1971-2000 (N.J. State Climatologist, Rutgers University, New Jersey, unpub. data,
accessed Feb. 14, 2005, on the World Wide Web at URL http://climate.rutgers.edu). Water levels in wells
completed in unconfined and fractured rock aquifers are directly related to the amount of annual precipitation,
which was more than 7 inches below average during the 2005 water year. The highest ground-water levels of the
year in many wells occurred during the first week of April after a period of above average rain and snow. Groundwater
The effects of climate on daily mean water levels in six observation wells during water year 2005 can be seen in the hydrographs shown in figure 1. These wells are all part of the USGS- NJDEP Drought Monitoring Network. Monthly extreme and long-term average water levels are shown for comparison. The Taylor, Readington 11, and Cranston Farms 15 observation wells (NJ-WRD well numbers 37-202, 19-270, and 21-364) which are open to fractured-rock aquifers, had below average water levels for the period from April through September. The Morrell 1, Lebanon State Forest 23-D, and Vocational School 2 observation wells (NJ-WRD well numbers 23-104, 5-689, and 11-42) tap unconfined sand and gravel aquifers. Water levels in wells tapping the Kirkwood-Cohansey aquifer declined from April through September but remained in the normal range.
Water levels in most wells that tap unconfined aquifers in the Coastal Plain exhibit the effects of recent climate patterns. Water levels in these wells, in general, are similar regardless of which aquifer the wells are completed in. The low water levels in 1995, 1998, 1999, 2001, and 2002 are the result of dry years, and the high water levels in 2003, 2004, and the first 6 months of 2005 are the result of the recent wet years. In many of these wells, water levels dropped in the last 6 months of 2005 because of the dry conditions. In shallower wells, water levels were approaching levels seen in the 2002 drought year by the end of the 2005 water year.
For wells that tap fractured rock aquifers and stratified drift deposits in northern New Jersey, trends in
Water levels in the confined aquifers in the Coastal Plain of New Jersey have been reacting to changes in withdrawals over the past 10 years. In 1986, NJDEP designated two “Critical Water-Supply Management Areas” in the New Jersey Coastal Plain. (See figure 2.) This designation was initiated as a result of concern about long-term declines in ground-water levels in these areas where ground water is the primary source of water supply. Groundwater withdrawals from specified aquifers in these areas were reduced, and new allocations may be limited. In Critical Area 1, withdrawals from the Wenonah-Mount Laurel aquifer, Englishtown aquifer system, and Upper and Middle Potomac-Raritan-Magothy aquifers are restricted. In Critical Area 2, withdrawals from the Potomac- Raritan-Magothy aquifer system have been restricted since 1996.
In Critical Area 1, water levels rose dramatically in wells completed in the Potomac- Raritan-Magothy aquifer system, Englishtown aquifer system, and Wenonah-Mount Laurel aquifer from 1991 to 1998. This rise in water levels was the result of the reduction in ground-water withdrawals from deep, confined aquifers; an increase in withdrawals from shallower aquifers; and a shift in withdrawals from ground-water to surface-water sources. In Critical Area 2, the shift in withdrawals away from the deeper, confined aquifers to surface water and ground water in shallower, confined and unconfined aquifers began in 1996. As a result, beginning in 1996 water levels rose in many observation wells screened in the Potomac-Raritan-Magothy aquifer system in Critical Area 2.
Water levels measured in confined aquifers in the Coastal Plain in water year 2005, together with those measured during previous years, show the effects of the Critical Area cutbacks and changes in ground-water withdrawal patterns. Although water levels in these confined aquifers generally are not affected by climatic conditions (except near the aquifer outcrop areas) some wells exhibit low water levels in dry years (1999 and 2002). These low levels probably are due to increased demand during dry years. Changes in water levels in each of the confined aquifers in the Coastal Plain are summarized in the following paragraphs.
Water levels in the confined Cohansey aquifer in Cape May County have been relatively constant (slight long-term decline of 2-5 feet over the past 10 years) in wells in the northern part of the county. In wells in the southern part of the county (9-48, 9-49, and 9-150), water levels have recovered as much as 5 feet since 1999 as a result of a reduction in withdrawals related to the use of a desalinization plant in Cape May City, which has provided water for public supply since 1998.
Water levels in the Atlantic City 800-foot sand have been affected by withdrawals for the desalination plant. Water levels in the Coast Guard 800 observation well (NJ-WRD well number 9- 302) have declined more than 10 feet since 1998, and water levels in two wells located north of the desalinization plant (9-306 and 9-337) have declined 2 to 4 feet since 1998. In Atlantic County, water levels in two wells have been relatively stable over the past 5 years (1-578, and 1- 702). Two wells, one in Galloway Township and one in Egg Harbor Township, exceeded their previous low of record (01-180 and 01-0703).
Water levels in the Piney Point aquifer throughout much of the southern part of the State continue to decline. Steady declines of 3 to 10 feet have occurred over the past 10 years in several wells completed in the Piney Point aquifer (1-834, 1-1219, and 29-1210). Water levels in three wells in Cumberland County declined from 13 to 43 feet between December 2003 and September 2005 (11-44, 11-96, and 11-163) as a result of increased withdrawals in the area. Water levels in the aquifer in parts of Ocean and Burlington Counties have been relatively stable (5-407, 5- 676, and 29-425).
Water levels in the Vincentown aquifer have remained stable over the past 10 years. Water levels in two wells located near the outcrop of the aquifer (5-1250 and 25-636) decline 1 to 3 feet during periods of drought.
Water levels in the Wenonah-Mount Laurel aquifer in parts of Burlington, Camden, Gloucester, and Salem Counties had been declining over the last several years but leveled off during 2002-05 (5-1155, 5-1387,and 7-478). The greatest long-term water-level decline in a confined aquifer observation well has occurred in the New Brooklyn Park 3 observation well (07- 478), which is screened in the Wenonah-Mount Laurel aquifer in Camden County. The water level in this well declined more than 86 feet from December 1962 to December 2001 but recently has leveled off. Water levels in the northern part of the aquifer leveled off in the late 1990’s after recovering as a result of Critical Area 1 withdrawal cutbacks. Water levels in two wells in Monmouth County set record highs during the 2005 water year (25-486 and 25-637).
Water levels in observation wells that tap the Englishtown aquifer system recovered and seemed to have leveled off during recent years in the northern part of the aquifer as a result of Critical Area 1 withdrawal cutbacks (25-715, 29-138, and 29-530). Water levels in wells in southern Monmouth and northern Ocean Counties rose during the 2005 water year (25-429 and 29-503). The water level in the Toms River 2 Obs well (29-534) in central Ocean County has risen by over 25 feet over the past 10 years. Water levels in the Englishtown aquifer system have been recovering since 2003 at two wells in Burlington County (5-259 and 5-1390).
Water levels in the Potomac-Raritan-Magothy aquifer system have been affected by cutbacks in withdrawals in both Critical Areas. Water levels recovered through the late 1990’s in the northern part of the aquifer system as a result of the decreased withdrawals in Critical Area 1 but have declined slightly in recent years at several wells (25-272, 25-639, 29-85). In the vicinity of Critical Area 2 (Burlington, Camden, and Gloucester Counties), water levels began rising in 1996. A continuation of that slow recovery can be seen in water-level hydrographs of 19 wells (5- 63, 5-258, 5-261, 5-262, 5-645, 5-683, 7-117, 7-283, 7-412, 7-413, 7-476, 7-477, 15-671, 15-741, 15-742, 15-772, 15-773, 33-187 and 33-841) in Critical Area 2.