Water-level conditions in the confined aquifers of the New Jersey Coastal Plain, 2013
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First posted February 12, 2021 For additional information, contact: Director, New Jersey Water Science CenterU.S. Geological Survey3450 Princeton PikeSuite 110Lawrenceville, NJ 08648Contact Pubs Warehouse The Coastal Plain aquifers of New Jersey provide an important source of water for more than 3.5 million people. In 2013, groundwater withdrawals from 10 confined aquifers of the New Jersey Coastal Plain totaled about 190 million gallons per day. Steadily increasing withdrawals from the late 1800s to the early 1990s resulted in declining water levels and the formation of regional cones of depression in many confined Coastal Plain aquifers. Starting in 1978, the U.S. Geological Survey (USGS) began mapping the potentiometric surfaces of the major confined Coastal Plain aquifers every 5 years to provide a regional assessment of groundwater conditions.In a study conducted by the USGS, in cooperation with the New Jersey Department of Environmental Protection, water levels in 10 confined aquifers of the New Jersey Coastal Plain were measured and evaluated to provide a regional overview of groundwater conditions during fall 2013. Water levels were measured in 987 wells in New Jersey, and parts of Pennsylvania and Delaware. Potentiometric-surface maps were prepared for, in ascending order of age, the confined Cohansey aquifer of Cape May County, Rio Grande water-bearing zone, Atlantic City 800-foot sand, Piney Point aquifer, Vincentown aquifer, Wenonah-Mount Laurel aquifer, Englishtown aquifer system, and the Upper, Middle, and Lower aquifers of the Potomac-Raritan-Magothy (PRM) aquifer system.Persistent, regionally extensive cones of depression were present in the potentiometric surfaces of the Englishtown aquifer system and Wenonah-Mount Laurel aquifer in Ocean and Monmouth Counties; Wenonah-Mount Laurel and Upper, Middle, and Lower PRM aquifers in Camden County; and Atlantic City 800-foot sand in Atlantic County. Changes in water levels from 2008 to 2013 were measured in many Coastal Plain aquifers in New Jersey. In some areas, water levels continued to decline as a result of pumping, but in other areas water levels continued to recover as a result of regulated decreases in groundwater withdrawals. Since 2008, in the confined Cohansey aquifer in Cape May County, water levels generally did not change; however, cones of depression in the potentiometric surface of the Piney Point aquifer in some areas of Cumberland County deepened by more than 20 feet (ft). In Critical Area 1, an area of restricted withdrawals, measured water levels in the Wenonah-Mount Laurel aquifer declined in parts of southern Monmouth County by more than 10 ft; however, rises in water levels of more than 10 ft were measured in parts of northern Ocean and Monmouth Counties. Since 2008, in Critical Area 2, also an area of restricted withdrawals, measured water levels in the Wenonah-Mount Laurel aquifer rose more than 20 ft in parts of western Burlington County and more than 20 ft in parts of western Camden County. Since 2008, in Critical Area 1, measured water levels in the Englishtown aquifer system declined in parts of eastern Ocean County by more than 10 ft and in southeastern Monmouth County by more than 20 ft; however, rises in water levels of more than 10 ft were measured in other parts of Ocean and Monmouth Counties.In general, since 2008 in Critical Area 2, in the Upper PRM aquifer, measured water levels continued to rise by 10 ft or more in central and western Burlington and central Camden Counties. In the Middle PRM aquifer in Critical Area 2, measured water levels rose in parts of central Camden County by 10 ft or more. However, measured water levels in the Lower PRM aquifer in Critical Area 2 were more than 10 ft lower in the center of the cone of depression in central Camden County, but measured water levels continued to rise updip from this area in Critical Area 2.Seasonal water-level fluctuations are presented in time-series hydrographs for 77 wells during 1978–2013. Analyses of long-term water-level changes for the period 2008–13 indicate downward water-level trends at 14 wells (18 percent), upward trends at 34 wells (44 percent), and no substantial change at 29 wells (38 percent). Downward trends were most often observed for wells screened in the Piney Point aquifer and the Atlantic City 800-foot sand. Upward water-level trends were most often measured for wells screened in the PRM aquifer system. Upward water-level trends also were measured for wells in the Englishtown aquifer system and the Wenonah-Mount Laurel aquifer in Critical Area 1 in some areas; however, downward trends and no substantial changes were measured in other areas.Keywords:
Surficial aquifer
Coastal plain
Cone of depression
Geological survey
Aquifer test
The St. Peter-Jordan aquifer includes the Cambrian Jordan Sandstone and the overlying Ordovician Prairie du Chien Group and St. Peter Sandstone. The aquifer is present throughout Iowa and is confined beneath other aquifers in much of the State. Information on the aquifer available from drillers and contractors, provided estimates of aquifer transmissivity values ranging from about 500 to about 3,000 square feet per day. The largest transmissivity values are for dolomite and dolomite-cemented sandstone, indicating that permeability in much of the aquifer is due to secondary fractures. The aquifer is vertically bounded by an upper leaky confining unit with a vertical hydraulic conductivity of 10-10 feet per second. The aquifer was simulated using a two-layer finite-difference ground-water flow model. The upper layer simulated a source bed in aquifers composed of Silurian and Devonian rocks overlying the St. Peter-Jordan aquifer. The lower layer simulated flow in the St. Peter-Jordan aquifer. Lateral boundaries assigned in the model include constant heads in northeastern Iowa, where the aquifer is in contact with the Mississippi River or is unconfined, and no-flow boundaries in western and northwestern Iowa, where the rocks are insufficiently permeable to form an aquifer. The aquifer boundaries to the north, east, and south of Iowa were determined by geohydrologic conditions and the relation of the St. Peter-Jordan aquifer with the lateral extent of adjacent aquifers. An assumption that the largest part of recharge to the aquifer is from outcrop areas in northeastern Iowa and from Minnesota is not supported by the results of this study. Vertical leakage from overlying rocks accounted for most of the recharge to the aquifer in northwestern Iowa. Discharge is mostly through lateral boundaries and to rivers. Pumping has caused changes in the flow system that include regional declines in the potentiometric surface of the aquifer. Simulation indicates that pumping through 1980 increased net vertical leakage into the aquifer to about double the predevelopment rate. Discharge across lateral boundaries has been substantially reduced or reversed by pumping. Aquifer storage provided about one-third of the water required to supply pumping in the 1970's. Simulation of future conditions, assuming no increase in pumping rates, indicates that the rate of decline in water levels will decrease by the year 2020. As equilibrium with pumping is approached in 2020, 75 percent of the pumpage will be balanced by vertical leakage, eight percent by water released from aquifer storage, and 17 percent by increases in boundary recharge or decreases in boundary discharge. Future pumping at an increasing rate of about 10 percent per decade of the average pumping rate in 1975 will require about one and one-half times the vertical leakage of the 1971-1980 period and about fivetimes the net inflow from lateral boundaries; however, the rate of water released from aquifer storage will be about half the 1970's rate. Under these conditions, the head in the aquifer will continue to decline at an almost constant rate until 2020.
Cone of depression
Aquifer test
Surficial aquifer
Outcrop
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Water levels and changes in water levels in the major aquifers of the New Jersey Coastal Plain are documented. Water levels in 1,071 wells were measured in 1983, and are compared with 827 water level measurements made in the same wells in 1978. Increased groundwater withdrawals from the major artesian aquifers that underlie the New Jersey Coastal Plain have caused large cones of depression in the artesian heads. These cones are delineated on detailed potentiometric surface maps based on water level data collected in the fall of 1983. Hydrographs from observation wells show trends of water levels for the 6-year period of 1978 through 1983. The Potomac-Raritan-Magothy aquifer system is divided into the lower, middle, and upper aquifers. The potentiometric surfaces in these aquifers form large cones of depression centered in the Camden and Middlesex-Monmouth County areas. Measured water levels declined as much as 23 ft in these areas for the period of study. The lowest levels are 96 ft below sea level in Camden County and 91 ft below sea level in the Middlesex-Monmouth County area. Deep cones of depression in coastal Monmouth and Ocean counties in both the Englishtown aquifer system and Wenonah-Mount Laurel aquifer are similar in location and shape. This is because of an effective hydraulic connection between these aquifers. Measured water levels declined as much as 29 ft in the Englishtown aquifer system and 21 ft in the Wenonah-Mount Laurel aquifer during the period of study. The lowest levels are 249 ft below sea level in the Englishtown aquifer system and 196 ft below sea level in the Wenonah-Mount Laurel aquifer. Water levels in the Piney Point aquifer are as low as 75 ft below sea level at Seaside Park, Ocean County and 35 ft below sea level in southern Cumberland County. Water levels in Cumberland County are affected by large withdrawals of groundwater in Kent County, Delaware. Water levels in the Atlantic City 800 ft sand of the Kirkwood Formation define an extensive elongated cone of depression. Water levels are as low as 76 ft below sea level near Margate and Ventnor, Atlantic County. Measured water levels declined as much as 9 ft in the coastal region between Cape May County and Ocean County for the period of study. (Author 's abstract)
Cone of depression
Coastal plain
Surficial aquifer
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Aquifers in the Nacatoch Sand and Tokio Formation in southwestern Arkansas are a source of water for industrial, public supply, domestic, and agricultural uses. Water-level measurements were made in 24 wells completed in the Nacatoch Sand and 18 wells completed in the Tokio Forma tion from August through October 1996 to pro duce potentiometric-surface maps. The direction of ground-water flow in aquifers in the Nacatoch Sand and Tokio Formation generally is to the south-southeast or southeast. Potentiometric highs for both aquifers are in the outcrop areas. The aquifer in the Tokio Formation has artesian flow in southeastern Pike, northeastern Hempstead, and northwestern Nevada Counties. One apparent cone of depression was evident within the study area in the aquifer in the Nacatoch Sand. Withdrawals from aquifers in the Nacatoch Sand and Tokio Formation increased from 1965 to 1980 and decreased from 1980 to 1995. Long-term hydrographs were prepared for seven wells in the study area. Changes in water levels in three wells completed in the aquifer in the Nacatoch Sand and one well completed in the aquifer in the Tokio Formation might be associated with decreased withdrawals. Evidence of an association between withdrawals and water levels in three wells is not apparent.
Surficial aquifer
Cone of depression
Outcrop
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ABSTRACT: A variable change is used to convert drawdown formulas for isotropic aquifers for use where the aquifer is anisotropic. Contours of the cone of depression assume an oval configuration with the major and minor axes oriented in the directions for which the permeability is greated and least. The case of a well pumped at a constant rate, the case of a well drawing water at a constant rate from an aquifer with a leaky roof and the flowing artesian well case are treated. In all cases the well is considered to completely penetrate the aquifer.
Cone of depression
Aquifer test
Drawdown (hydrology)
Constant (computer programming)
Water well
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The Prairie du Chien-Jordan aquifer is a major source of water for many communities in southeastern Minnesota. The water-supply well for the Shakopee Mdewakanton Sioux Community derives water from the Jordan part of the aquifer. An aquifer test in the Prairie du Chien-Jordan aquifer in the area of the Shakopee Mdewakanton Sioux Community was completed in November 1995. The test consisted of pumping water from a public works well open to the Jordan part of the aquifer and measuring drawdown in this well and two observation wells. This was followed by measuring recovery in the wells after the pumping was terminated. The Neuman (1974) method for unconfined aquifers was used to analyze data collected from the two observation wells during the drawdown and recovery periods, resulting in a range of estimated aquifer hydraulic properties. Aquifer transmissivity ranged from 4,710 to 7,660 ft2/d and aquifer storativity ranged from 8.24 x 10-5 to 1.60 x 10-4. These values are generally in close agreement for all four sets of data, given the limitations of the test, indicating that the test results are accurate and representative of the aquifer hydrogeologic properties. The lack of late-time data made it impossible to accurately assess aquifer specific yield.
Drawdown (hydrology)
Aquifer test
Surficial aquifer
Cone of depression
Aquifer properties
Water well
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A connector well pilot installation, in continuous operation in western Orange County since December 4, 1970, was transferring water from the lower of two shallow sand aquifers to the Floridan aquifer at a rate of 13 gallons per minute when measured on September 23, 1971. The recharge water is untreated and analyses show it to be chemically and physically compatible with the water in the Floridan aquifer. The temperatures of the recharging and receiving waters were identical, 23 deg C. The transfer of water from the lower sand aquifer to the Floridan aquifer caused only a small buildup of artesian pressure in the Floridan aquifer but it lowered the artesian head 4 feet in the lower sand aquifer near the well which supplied the recharge water. Water levels in the upper sand aquifer were not affected, probably because of the low permeability of an intervening hardpan layer. However, after six auger holes back-filled with sand connected the two sand aquifers on April 5, 1972, a rise of water levels in the lower sand aquifer was noted. The principal chemical and physical effects on the water in the Floridan aquifer were a general improvement in chemical quality and an increase in color. The color may decrease as more water moves through the sand aquifer and the material responsible for the high color is removed by flushing. (Woodard-USGS)
Surficial aquifer
Aquifer test
Cone of depression
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The Elm aquifer, which consists of sandy and gravelly glacial-outwash deposits, is present in several counties in northeastern South Dakota. An aquifer test was conducted northeast of Aberdeen during the fall of 1999 to determine the hydraulic properties of the Elm aquifer in that area. An improved understanding of the properties of the aquifer will be useful in the possible development of the aquifer as a water resource. Historical water-level data indicate that the saturated thickness of the Elm aquifer can change considerably over time. From September 1977 through November 1985, water levels at three wells completed in the Elm aquifer near the aquifer test site varied by 5.1 ft, 9.50 ft, and 11.1 ft. From June 1982 through October 1999, water levels at five wells completed in the Elm aquifer near the aquifer test site varied by 8.7 ft, 11.4 ft, 13.2 ft, 13.8 ft, and 19.7 ft. The water levels during the fall of 1999 were among the highest on record, so the aquifer test was affected by portions of the aquifer being saturated that might not be saturated during drier times. The aquifer test was conducted using five existing wells that had been installed prior to this study. Well A, the pumped well, has an operating irrigation pump and is centrally located among the wells. Wells B, C, D, and E are about 70 ft, 1,390 ft, 2,200 ft, and 3,100 ft, respectively, in different directions from Well A. Using vented pressure transducers and programmable data loggers, water-level data were collected at the five wells prior to, during, and after the pumping, which started on November 19, 1999, and continued a little over 72 hours. Based on available drilling logs, the Elm aquifer near the test area was assumed to be unconfined. The Neuman (1974) method theoretical response curves that most closely match the observed water-level changes at Wells A and B were calculated using software (AQTESOLV for Windows Version 2.13-Professional) developed by Glenn M. Duffield of HydroSOLVE, Inc. These best fit theoretical response curves are based on a transmissivity of 24,000 ft2/d or a hydraulic conductivity of about 600 ft/d, a storage coefficient of 0.05, a specific yield of 0.42, and vertical hydraulic conductivity equal to horizontal hydraulic conductivity. The theoretical type curves match the observed data fairly closely at Wells A and B until about 2,500 minutes and 1,000 minutes, respectively, after pumping began. The increasing rate of drawdown after these breaks is an indication that a no-flow boundary (an area with much lower hydraulic conductivity) likely was encountered and that Wells A and B may be completed in a part of the Elm aquifer with limited hydraulic connection to the rest of the aquifer. Additional analysis indicates that if different assumptions regarding the screened interval for Well B and aquifer anisotropy are used, type curves can be calculated that fit the observed data using a lower specific yield that is within the commonly accepted range. When the screened interval for Well B was reduced to 5 ft near the top of the aquifer and horizontal hydraulic conductivity was set to 20 times vertical hydraulic conductivity, the type curves calculated using a specific yield of 0.1 and a transmissivity of 30,200 ft2/d also matched the observed data from Wells A and B fairly well. A version of the Theim equilibrium equation was used to calculate the theoretical drawdown in an idealized unconfined aquifer when a perfectly efficient well is being pumped at a constant rate. These calculations were performed for a range of pumping rates, drawdowns at the wells, and distances between wells that might be found in a production well field in the Elm aquifer. Although the aquifer test indicates that hydraulic conductivity near the well may be adequate to support a production well, the comparison of drawdown and recovery curves indicates the possibility that heterogeneities may limit the productive capacity of specific loca
Aquifer test
Cone of depression
Specific storage
Surficial aquifer
Aquifer properties
Outwash plain
Slug test
Water well
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A solution for the drawdown in a large‐diameter well discharging at a constant rate from a homogeneous isotropic artesian aquifer, which also takes into consideration the water derived from storage within the well, is presented. A set of type curves computed from this solution permits a determination of the transmissibility of the aquifer by analysis of drawdown observed in the pumped well.
Drawdown (hydrology)
Aquifer test
Transmissibility (structural dynamics)
Constant (computer programming)
Water well
Cone of depression
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Transmissibility (structural dynamics)
Cone of depression
Aquifer test
Water well
Specific storage
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ABSTRACT Under field conditions the aquifer geometry rarely confirms to the concept of one aquifer system. In a borehole it is common to find number of aquifers. When the aquifers are separated by aquicludes, interaction between the aquifers is only through the well screens. However, when aquifer is separated by aquitards, the intersection between the aquifers takes place through the aquitards besides the well screens. In general, a tubewell has a strainer length of the aquifer depth. To curtail some cost of installation a partially penetrating well may be good provided the discharge does not drop down significantly due to partial penetration. But the hydraulics of a partially penetrating well in a leaky aquifer is different from that of confined aquifers. A well in a leaky aquifer withdraws water not only from the aquifer but also from the overlying semi- pervious layer. Steady case is possible in such case because o frecharge through the semi- pervious layer. During unsteady conditions the head varies with time. To study the relationships between drawdown-discharge of the well and radial distance, a sand tank model was developed. The experiements have been carried out in the sand tank model where a leaky aquifer environment was created. The results so obtained for five different degrees of penetration have been analysed for varying discharge conditions. KEY WORDS: WellAquiferSemi-confinedDischargeDrawdownDegree of penetrationRadius of influenceSand tank modelHydraulic conductivityPerviousLaminar
Aquifer test
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