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Ramapo Aquifer Systems Ramapo Aquifer Systems

Support Document

Bergen and Passaic Counties, New Jersey and
Orange and Rockland Counties, New York

August 1992

  • I. Introduction
  • II. Hydrogeology
  • III. Susceptibility to Contamination
  • IV. Alternative Sources of Drinking Water
  • V. Summary
  • VI. Selected References
  • VII. Table
    • Table 1. Municipalities Dependent on the Ramapo River Basin Aquifer Systems
  • VIII. Figures
    • Figure 1. Ramapo River Basin Aquifer Systems Designated Area
    • Figure 2. Location of the Ramapo River Basin within the Passaic River Basin Drainage System
    • Figure 3. Ramapo River Basin
    • Figure 4. Physiographic Provinces of Ramapo River Basin
    • Figure 5. General Geology of Northeastern New Jersey and the Adjacent Part of New York
    • Figure 6. Comparison of the Mean Chemical Quality of Water from Three Major Aquifers in the New Jersey Part of the Ramapo River Basin
  • I. Introduction

    A. Statement of Section 1424 (e)

    The Safe Drinking Water Act (SDWA), Public Law 93-523, of December 16, 1974 contains a provision in Section 1424(e), which states that:

    If the Administrator determines, on his own initiative or upon petition, that an area has an aquifer which is the sole or principal drinking water source for the area and which, if contaminated, would create significant hazard to public health, he shall publish notice of that determination in the Federal Register. After the publication of any such notice, no commitment for Federal financial assistance (through a grant, contract, loan guarantee, or otherwise) may be entered into for any project which the Administrator determines may contaminate such aquifer through a recharge zone so as to create a significant hazard to public health, but a commitment for Federal financial assistance may, if authorized under another provision of law, be entered into to plan or design the project to assure that it will not so contaminate the aquifer.

    This section allows for the specific designation of areas which are dependent upon ground water supplies. Following designation, the review process will ensure that federal agencies will not commit funds toward projects which may contaminate these ground water supplies.

    B. Receipt of Petition

    On September 8, 1990 the Township of Mahwah and the Passaic River Coalition petitioned the U.S. Environmental Protection Agency (EPA) Administrator to declare the Ramapo River Basin Aquifer Systems, consisting of the complex of aquifers within the Ramapo River Basin, as defined in the petition, a Sole Source Aquifer (SSA) under the provisions of the SDWA. The petition further asks the Administrator to designate the entire Ramapo River Basin as a SSA.

    C. Area of Consideration

    The boundary of the area of consideration specified in the petition submitted by the Township of Mahwah and the Passaic River Coalition is defined as the Ramapo River Basin Aquifer Systems. Thirty percent (30%) of the Ramapo River Basin Aquifer Systems is in New Jersey, and includes parts of Passaic and Bergen Counties; and seventy percent (70%)of the area is in New York and includes parts of Orange and Rockland Counties.

    The aquifer area specified by the petition is defined by the Ramapo River Basin Aquifer Systems, consisting of the hydraulically connected aquifers contained within the Ramapo River Basin. The aquifers include the highly productive valleyfill aquifer in the Ramapo and Mahwah river valleys, and the bedrock aquifer which underlies the eastern portion of the Ramapo River Basin, east of the Ramapo River in New Jersey and the Mahwah River in New York.

    Description of Project Review Areas

    The Ramapo River Basin Aquifer Systems generally underlie the eastern portion of the Ramapo River Basin which extends from Great Border Fault, east to the Ramapo River Basin boundary. The aquifers include the valleyfill aquifer in the Ramapo and Mahwah river valleys and the Newark Group. In New York, the aquifers include the New York Department of Environmental Conservation (NYSDEC) designated Ramapo Mahwah Primary Aquifer as illustrated in the U.S. Geological Survey Water Resources Investigations Report 874274 Potential Yields in Unconsolidated Aquifers in Upstate New York Lower Hudson Sheet, Scale 1:250,000. The aquifer is delineated in detail on the U.S. Geological Survey Open File Report 82114, Geohydrology of the Valley Fill Aquifer in the Ramapo and Mahwah Rivers Area Rockland County. New York, Scale 1:24,000. In New Jersey, the aquifers include the valleyfill aquifer in the Mahwah and Ramapo river valleys. The Ramapo River valleyfill aquifer is described and profiled in the New Jersey Geological Survey Map Series 886 Bedrock Topography and Profiles of Valley Fill Deposits in the Ramapo River Valley. New Jersey, Scale 1:24,000.

    In New York and New Jersey, the aquifers include the Newark Group bedrock aquifer, which underlies the eastern portion of the Ramapo River Basin, east of the Ramapo River in New Jersey and the Mahwah River in New York.

    The SSA includes the aquifer recharge areas defined as the entire Ramapo River Basin, which encompasses all streamflow source areas including the Ramapo River headwaters near Monroe, New York. The project review area is coincident with the Ramapo River Basin boundaries.

    D. Topography

    The Ramapo River Basin is part of the Passaic River drainage system. The basin is part of the Appalachian Highlands division that includes several physiographic provinces. Of these, parts of the New York New Jersey Highlands and Piedmont Provinces characterize the Basin. The boundary between these two Provinces follows the Ramapo River valley in New Jersey and continues up the Mahwah River valley in New York.

    The New York New Jersey Highlands Province within the basin is characterized by rugged terrain. The Ramapo Mountains, one of whose peaks reaches an altitude of 1,164 feet are part of the basin. The Piedmont Province is characterized by less rugged terrain consisting of hills elongated in a northsouth to northwestsouthwest direction.

    E. Climate

    The climate of the Ramapo River Basin is characterized as continental climate due to the prevalence of westerly winds from the continental interior. Prevailing wind directions are from the northwest from October to April and from the southwest during the rest of the year. Average winter temperatures are in the high twenties and low thirties on the Fahrenheit scale. Average summer temperatures are in the mid seventies. Midsummer weather is characterized by high humidity and frequent thunderstorms.

    Virtually all water both above and below the land surface within the basin area originates as precipitation. Average annual precipitation measured during the period from 1921 1950 ranged from 43 inches at the streamflow source area near Monroe, New York, to 47 inches near Pompton Lakes, New Jersey, the southernmost part of the basin. Based on an average rainfall of 45 inches, the runoff percentage is calculated to be fifty-six percent (56%) and the evaporation percentage forty-four percent (44%).

    II. Hydrogeology

    A. Geologic Framework

    The Ramapo River drains an area of 161 square miles, of which, 112.4 square miles are in New York State (Vermeil, 1894). The drainage basinincludes parts of Orange and Rockland Counties, in New York, and parts of Passaic and Bergen Counties in New Jersey. The total channel length of the Ramapo is thirty-four miles (34 mi.) (Vermeil, 1894). The Mahwah River -- the Ramapo's major tributary-- joins the Ramapo just south of the New York--New Jersey State line.

    The part of the Ramapo River Basin Aquifer Systems in New Jersey is rather sparsely populated, as compared with most of the other areas in northeastern New Jersey. West of the Ramapo River, most of the area is mountainous and wooded and is poorly suited for urbanization or major development. Practically all development in the New Jersey part of the basin has been east of the river and has been largely residential. East of the river, the topography is hilly, and much of it is also wooded. One of the notable industries with in the basin is a large automobile assembly plant near Mahwah. Continued suburban development of the general area is anticipated.

    The Ramapo River Basin Aquifer Systems is part of the Appalachian Highlands division that includes several physiographic provinces. Of these, parts of the New England and Piedmont provinces characterize the basin. The boundary between these two provinces follows the valley of the Ramapo River in New Jersey, and it continues up the Mahwah River valley in New York.

    Within the New Jersey part of the basin, the New England province, known locally as the New Jersey Highlands, consists of the rugged Ramapo Mountains. One of these mountain peaks reaches a maximum altitude of 1,164 feet above mean sea level, half a mile southwest of the State line, in the westernmost part of the basin. Many other peaks, particularly in the northern part of the range, reach altitudes of more than 900 feet; however, in the southern part of the range, the altitudes are lower.

    The Piedmont province--that part of the basin southeast of the river--is marked by less rugged hills elongated in a northsouth to northwest-southeast direction, and the highest altitude in the province, 750 feet above mean sea level, is that of a ridge near Campgaw that is the northernmost extension of the Watchung Mountains. Extensive swampy areas occur in the headwaters of many of the tributary streams in this part of the basin. Consequently, the drainage divide between the Ramapo River and the Saddle River, to the east, is poorly defined in some places.

    B. Geologic Setting

    Various rock types, representing several geologic time periods and ranging in age from Precambrian to Holocene, crop out in the Ramapo River basin. The areal extent of the various rock units is shown in figure 2.


    Crystalline rocks of Precambrian age underlie almost all of the basin area west of the Ramapo River in New Jersey, as well as most of the New York part of the basin. These rocks, for the most part, are gneisses that is metamorphic granitoid, or granite-like, rocks. The gneiss are part of a mountainous north-east belt across northern New Jersey, known as the JerseyHighlands. The Ramapo Mountains mark the southeast border of the Highlands. These Precambrian rocks are believed to be deeply buried beneath the Triassic rocks to the east and to underlie all other rocks in northern New Jersey, as they are the oldest rocks known to occur in the area.

    Limestones of early and middle Paleozoic age underlie the headwaters area of the Ramapo River in Orange County, N.Y., but they are not known to occur in the New Jersey part of the basin. These limestones are mentioned briefly, however, because of their effect on the chemical surface water quality of the water downstream.


    The Newark Group of Late Triassic age crops out across northern New Jersey in a northeast trending belt that ranges in width from thirty-two miles (32 mi.) along the Delaware River to fifteen miles (15 mi.) at the New York State line. From Pompton Lakes north to the New Jersey-New York State line, the Newark Group underlies the entire area east of the Ramapo River, to as far as the Hudson River. These rocks are truncated on the west by a major fault zone, called the Great Border fault, where the rocks of the Newark Group lie against the Precambrian crystalline rocks. The Ramapo River outlines the trend of the fault zone in New Jersey, and the Mahwah River follows the trend of the fault zone in New York.

    The Newark Group is made up of both sedimentary and igneous

    rocks. In the western part of the outcrop area in New Jersey, the Newark Group consists of three units, from oldest to youngest, as follows (Kummel, 1899): Stockton, Lockatong, and Brunswick Formations. However, in the northeastern part of the State, the Newark Group consists entirely of the Brunswick Formation interlayered with Watchung Basalt, except for a narrow exposure of Stockton Formation that flanks both sides of the Palisade sill (diabase) along the Hudson River.

    The Brunswick Formation in the Ramapo River Basin is made up largely of sandstone and conglomerate containing interbedded shale. The Brunswick beds in the southwestern part of the outcrop area in New Jersey and at the type locality are chiefly soft red shales. According to Kummel (1899), however, "northward the shales grade into sandstones which are frequently conglomerated. This is notably the case in Bergen County where every exposure of any extent shows beds of sandstone and even conglomerate interlayered with the shales. The increasing coarseness continues into Rockland County [N.Y.], where the great mass of the formation appears to be sandstone and conglomerate, rather than argillaceous shale."

    The Triassic igneous rocks--the extrusive Watchung Basalt of the Newark Group and the intrusive diabase are commonly called trap rock. These rocks are much harder and more resistant to erosion than most sedimentary rocks, and they commonly form hills and ridges considerably above the general altitude of the sedimentary rocks. Examples are the Watchung Mountains, composed of basalt, and the Palisades, composed of diabase.

    Regionally the dominant strike of the Newark Group is to the northeast, with the beds dipping gently to the northwest. However, locally in the basin, in Bergen and Rockland Counties, the strike differs markedly and is more nearly to the north to northwest (Kummel, 1899).


    Unconsolidated rocks of Quaternary age mantle the bedrock almost everywhere in the basin. These surficial deposits consist of unstratified and stratified drift deposited by the "Wisconsin" Glacier and its melt waters during the Pleistocene Epoch of the Quaternary Period. To a much lesser extent, Holocene alluvial deposits, which are largely reworked Pleistocene sediments, occur along stream channels.

    Unstratified drift, or till, which is commonly a mixture of particles ranging in size from clay to boulders, occurs over most of the area. The till coveron the gneiss is generally thin, a few feet to a few tens of feet thick, and bedrock exposure are numerous, particularly on steep slopes and summit. The till cover on the Triassic rocks is somewhat thicker--generally on the order of a few feet to many tens of feet thick, and, in some places, is more than one-hundred feet (100') thick. The till cover on the Triassic rocks is commonly thinnest on the crests of the trap ridges and thickest on the lower lands.

    In the New Jersey part of the basin, extensive deposits of stratified drift--chiefly sand and gravel--occur only over the Triassic rocks. Hydrologically, the most important deposits are the sand and gravel deposits in the Ramapo River. The River is bordered by terraces of stratified drift from the New YorkNew Jersey State line south to Pompton Lakes. The terraces range in width from less than a quarter of a mile to nearly one mile and average about half a mile (Salisbury, 1902).

    Other extensive deposits of stratified drift occur in areas of Franklin Lake (in the southern part of Franklin Lakes) and Campgaw, and in the lowland between Ramsey and Mahwah. Most of the stratified drift around Franklin Lake forms a plain between First and Second Watchung Mountains that extends from the Ramapo valley on the northwest to about one mile east of the lake. Kames occur near the east border of the plain and, also, north of the lake. The drift is commonly one-hundred feet (100') thick in the Franklin Lake area, and drillers' records have reported it to be as much as one-hundred thirty-six feet (136') thick. In the Campgaw area the stratified drift occurs as kames, eskers, and irregular icecontact deposits. There, the maximum thickness of the drift ranges from about seventy-five to one-hundred feet (75 - 100'). The lowland from Ramsey to Mahwah is largely covered with stratified drift, some of which has formed eskers and kames. This very irregular shaped belt of stratified drift has an average width of about half a mile; however, little information is available on the thickness of these deposits. This belt connects with the belt of stratified drift along the Ramapo River near the New YorkNew Jersey State line.

    C. Surface Water

    The principal stream in the Ramapo River Basin is the Ramapo River which rises near Monroe in Orange County, New York, at an altitude of 690 feet, and headwaters of some of the minor tributaries rise at altitudes of as much as 830 feet.. The river flows through Monroe, Harriman, Arden and Sloatsburg before it crosses the State line into New Jersey near Mahwah. One-half mile downstream from the New York New JerseyState line, the Ramapo River is joined by the Mahwah River from the east. The Ramapo then flows in a generally southwesterly direction for about 12 miles to Pompton Lake, at the communities of Oakland and Pompton Lakes. After emerging from Pompton Lake, the Ramapo River flows south for about one mile and then joins the Pequannock River to form the Pompton River. The Pompton River flows into the Passaic River at Two Bridges.

    D. Ground Water Hydrology

    Some ground water can be obtained nearly everywhere in the basin. However, both the occurrence and the availability of ground water vary considerably according to the geologic materials underlying the different parts of area. In the consolidated rocks, fractures and solution cavities (secondary porosity) provide the principal means of storing and transmitting water, but, because these openings constitute only a very small part of the total volume of the rocks, the capacity of these rocks to store and transmit water is low. In the areas of unconsolidated rocks--principally in the Ramapo River valley, where sand and gravel occur--ground water occurs in interstitial openings (primary porosity) between the individual grains of these unconsolidated sediments. These openings constitute a relatively high percentage of the total volume of the sediments, and this, together with the high permeability of the sand and gravel, makes their capacity to store and transmit water much greater than that of the consolidated rocks. Although the clay and silt also have high porosity, they generally have very low permeability; hence, despite their great capacity to store water, their ability to transmit water is generally very low.

    Ground water generally occurs under watertable (unconfined) conditions throughout the basin. Although partial confinement results from discontinuities in permeability, and artesian conditions may prevail locally, no regional artesian aquifers are known anywhere in the basin. Virtually all the ground water in the basin originates within the basin as local precipitation. After moving through the aquifers, the ground water eventually discharges into the tributary streams or directly into the Ramapo River Basin Aquifer Systems and distributed by wells.


    Unweathered gneiss has a low primary porosity and, therefore, is relativelyimpermeable. Fracturing and weathering, however, develop secondary porosity and permeability. Thus, nearly all the ground water bearing gneiss is in the weathered zone near the land surface. Fault fractures and joints in the weathered zone have been enlarged by frost action, by plant roots, and by the dissolving action of circulating ground water. The waterbearing fractures decrease in size and number with depth, and it is generally not economically worthwhile to drill wells any more than two- to three-hundred feet (200 - 300') deep.

    Within the Ramapo River basin the depth to which water-bearing fractures occur in the gneiss may be even shallower. The gneiss constitutes the rugged topography of Ramapo Mountains, which indicates that the rock is resistant to erosion and is not easily weathered. In addition, because of the geologically recent glaciation, most of the severely weathered gneiss has been scoured away, and all that remains is fresh or only slightly weathered rock. Hence, in most of this area perhaps only the upper two-hundred feet (200') is water bearing.

    The yield of a well that taps the gneiss depends largely on the size and number of fractures penetrated by the well, a factor which varies considerably from place to place. The area underlain by gneiss is very sparsely settled, and little information is available on well yields. However, the data available indicate that at least a few gallons per minute are obtainable, even near the crest of the mountain. Large yields are not to be expected from the gneiss. When locating wells in the gneiss, the chances of drilling a well having a satisfactory yield would be greatest in the valleys or draws, as the valleys commonly are formed along fault zones or where the rock is more extensively jointed.

    For maximum well yields, wells tapping the gneiss should be thoroughly developed by such techniques as surging and (or) wire brushing to remove drill cuttings that may have sealed off the waterbearing fractures during the drilling. Use of a chemical aid, such as sodium hexametaphosphate, may also expedite the development process. The yield of a poor well is more apt to be improved from development of the well than from deepening the well much beyond two-hundred feet (200') because of the diminution in size and number of waterbearing fractures with depth. Although the storage capacity of the gneiss is very low, moderate and even high well yields can be obtained under favorable recharge conditions.


    Virtually all ground water in the Brunswick Formation, especially in the shale beds, occurs in interconnecting fractures that have resulted mainly from jointing. There is some additional void space in the sandstone and conglomerate beds where cementing material is lacking either because it was never deposited or because it has been dissolved and removed by circulating ground water. Perlmutter (1959) presented data which substantiates the conclusion that practically all the movement of ground water through these rocks takes place in fractures. In his samples, where the primary porosity of the rock was as high as twenty point nine percent (20.9%), the permeability was only 28 gpd per sq ft (gallons per day per square foot); and where the porosity was 15.5 and ten percent (10%), the permeability was zero.

    The most important fractures with respect to transmitting ground water are generally vertical joints (Knapp, 1904). Observations made by many observers at numerous places throughout the outcrop area of the Brunswick in New Jersey indicate that one set of vertical joints roughly parallels the strike of the rocks, and a second set is generally perpendicular to the strike. In places, the steeply dipping joints have different orientations. In addition, open bedding-plane joints are common in surface exposures, but they are thought to be of little water-bearing importance below the surface (Knapp, 1904; Herpers and Barksdale, 1951). Major and minor faults also occur in some places, and, locally, the fractures resulting from faulting may be the most important water bearers. In places, the water in these rocks occurs in only a few preferentially fractured zones, whereas in other places the ground water is more uniformly distributed throughout the upper few hundred feet of rock.

    Typically, ground water in sufflcient quantities for domestic purposes (10 gpm ) can be obtained nearly everywhere in the Brunswick Formation from wells that are six inches (6") in diameter and one- to two-hundred feet (100 - 200') deep. However, wells drilled in the Brunswick for maximum yield, such as for public supply or industrial use, are generally 8 or 10 inches in diameter and three- to four-hundred feet (300 - 400') deep. Reported yields of thirty large diameter (greater than 6") wells tested for maximum yield within and adjacent to the Ramapo River basin range from 48 to 240 gpm and average 137 gpm with the median yield being 125 gpm. The distribution of the yields is as follows:

    Yield (gpm) Number of Wells
    Less than 101 7
    101--200 20
    More than 200 3

    Because of the generally low specific capacity of the Brunswick wells, extreme care must be exercised in locating new wells near existing wells so that well interference will be at a minimum. Water levels in wells along the strike of the formation show greater interference than those in wells alined in transverse directions. Hence, well interference can be minimized by alining wells in directions other than parallel to the strike. Within the Ramapo basin the Brunswick Formation has a generally northerly strike, varying from northnorthwest to northnorth east; therefore, interference should be minimal in wells alined roughly eastwest. However, the local strike could be more precisely determined by an examination of outcrops in the vicinity of the site to be drilled.

    Moreover, knowledge of the hydraulic anisotropy is of impor tance when attempting to locate a well with respect to a potential source of pollution. If the well and the pollution source are alined parallel to the strike of the Brunswick, the chances of the well becoming polluted are greater than if the alinement is transverse to the strike.


    Ground water in the Watchung Basalt occurs mainly in fractures, but some occurs in vesicular zones, In describing the basalt sheets in the area just to the south of the Ramapo River basin, Darton, Bayley, Salisbury, and Kummel (1908) reported that vesicular zones are usually present at the bases of the sheets and that the upper parts of the sheets are vesicular to considerable depth. There is also evidence that the individual sheets are composed of multiple flows, and, hence, intrasheet vesicular zones may also be common. However, the most highly water bearing parts of the basalt are probably the uppermost and lowermost parts at or near the contact with the sandstone and shale of the Brunswick Formation. Ground water movement commonly is concentrated in these contact zones. Weathering associated with this ground water movement could enlarge fracture openings or increase interconnection of vesicles.

    Little information is available regarding the ability of basalt to yield water to wells in the Ramapo River basin, although numerous domestic wellsfurnish small supplies of ground water from the basalt. In nearby Morris County, yields of five public supply wells tapping basalt were reported to range from 30 to 54 gpm (Gill and Vecchioli, 1965). Nichols (1968) reported a range in yield from 146 to 400 gpm for seven public supply wells tapping basalt sheets in Essex County. The median yield of these wells is 250 gpm. However, these high yields pertain only to successful wells that are presently in use, and the many unsuccessful wells are not considered. These rocks probably should not be considered as sources of large ground water supplies. Locally, it may be possible to develop high capacity wells in them, but, in general, they seem capable of yielding only small to moderate supplies.


    Quarternary deposits mantle the bedrock practically everywhere in the basin. Because of their widespread surface occur precipitation and subsequently transmit the water downward to the underlying rock aquifer and laterally to streams. Where the saturated thickness of these deposits and their permeability are sufficiently great, they serve as aquifers. Indeed, the stratified drift in the Ramapo valley forms the most productive aquifer in the basin. The upland stratified drift deposits that occur in the vicinity of Franklin Lake and in the CampgawCrystal Lake area are of minor importance as aquifers.

    Wells that commonly yield several hundred gallons per minute and as much as 1,200 gpm with only five feet (5') of drawdown have been developed in the valley stratified drift (valley fill). These wells are of supply for the Township of Mahwah and the only source of supply for the Borough of Oakland. The valley fill is the most important aquifer in the basin.

    The upland stratified drift constitutes aquifers of local importance whereever its saturated thickness is on the order of several tens of feet, as at Franldin Lake and in the CampgawCrystal Lake area. The saturated thickness of the upland drift varies considerably from place to place, and, hence, it is difficult to predict the yield from a well completed in it. A well in Oakland is reported to yield 75 gpm from a saturated thickness of fifty feet (50'). A well in Franklin Lakes is reported to yield 200 gpm, also from a saturated thickness of fifty feet (50'); however, pumping of this well induces recharge from Shadow Lake, and its yield may therefore be atypical. The Borough of Oakland has recently completed a well which is reported to produce 582 gpm from drift and the underlying Brunswick Formation. Thedrift there has a saturated thickness of ninety feet (90').

    Data are not available to define the saturated thickness of the upland stratified drift everywhere. The most favorable thickness and, hence, the best places for well development in these deposits appear to be near Frank1in Lake and in the Campgaw-Crystal Lake area. Elsewhere, the deposits are generally thin or lacking.

    Till, because of its great heterogeneity in particle size, is generally poorly permeable and does not yield water readily to wells; hence, it is not considered to be an aquifer. However, till may have a porosity many times greater than that of the underlying rock, and its unit storage capacity would be correspondingly greater. The water stored in the till serves to replenish storage in the rock aquifer as the storage becomes depleted by wells.

    1. Recharge

    Recharge in this area by naturally occurring seepage from the Ramapo River during flood stages is considered to be a major source of recharge to the valleyfill aquifer. Also important is the recharge induced from the river by the withdrawal of water from wells tapping the aquifer.

    For the sand and gravel valleyfill deposits to supply high sustained well yields, the deposits must be hydraulically connected with the river in order to receive seepage from the river. In their study published in 1974, Vecchioli and Miller document the existence of the hydraulic connection between the Ramapo River and the valleyfill aquifer. The following approaches were utilized to illustrate the hydraulic connection:

    1. Intersection of natural groundwater level profiles with the Ramapo River.
    2. Correlation of fluctuations in both the Ramapo River stage and the groundwater level.
    3. Comparison of the seasonal variations in temperature of ground water and of surface water.
    4. Evaluation of pumping test data.
    5. Seepage looses.
    6. Comparison of chemical quality of water from the Ramapo with water from stratified drift.

    If ground water in a stream valley is hydraulically connected to the surface water, a profile showing the ground water level across the valley should intersect the stream. Vecchioli and Miller constructed a ground water level profile for one locality on the valley. At that locality the profile intersected the stream. Analysis of other static water level data in the valley indicated that ground water levels were about the same as the river stage opposite the wells sites.

    Fluctuations of groundwater levels in the stratified drift were observed near public supply well fields in the valley; (1) the Mahwah Water Department "Ford" wellfield, in the west side of the Ramapo River in Mahwah and (2) the Oakland Water Department "Soons" wellfield, on the east side of the river just below the Oakland Mahwah boundary. A correlation was found between fluctuations in stream stage and those in ground water levels in the wells.

    Ground water in the Ramapo River Basin, occurring at depths of several tens of feet to a few hundred feet, generally has a nearly constant yearround temperature that approaches the average annual air temperature of the area. Temperature of ground water at the Mahwah "Ford" wellfield was measured periodically during 1964, 1965, and part of 1966. The temperatures ranged from a low of about 8 degrees in the Centigrade scale in early April to a high of about 13.5 degrees in the Centigrade scale in late September. These temperature variations were not as great as the variations in surface water temperature. However, they are considered to be in excess of what would be normally expected in ground water.

    When a well is pumped the cone of depression continues to expand and deepen until it captures sufficient water to equal the water being discharged from the well. If a stream intersects the aquifer, water can be provided to the aquifer by the stream when the cone of depression expands to the stream. When this occurs, the drawdown cone ceases to expand or continues to expand at a much lower rate.

    A pumping test was conducted at the Oakland "Soons" wellfield to determine the presence or absence of a recharge boundary resulting from interaction of the drawdown cone with the nearby Ramapo River. The water level in an observation well was monitored during the pumping test. Analysis of the water level trends showed that the drawdown rates werevery high immediately after a pumpingrate increase. However, the rate of drawdown pumping increased abruptly within minutes after the rate of pumping is increased, indicating the presence of a recharge boundary close to the well field. Because the most likely nearby source of recharge was the Ramapo River, it was concluded that the river was the recharging boundary and that it is hydraulically continuous with the aquifer.

    Streamflow measurements to determine induced recharge to the stratified drift aquifer were made by Vecchioli and Miller on both the tributary streams and the main streams at several places; from Mahwah to Oakland. Seepage losses associated to pumpage of wellfields were noted.

    Comparison of chemical analyses of water from the Ramapo River with water from wells tapping the valleyfill deposits showed that the waters are similar. Hence the 14 data constitutes evidence for a possible a hydraulic connection.

    Further information on induced stream recharge to the valleyfill aquifer was obtained from the U.S. Geological Survey in New Jersey: a report on the Ramapo River Basin by M.C. Hill and others is in preparation by the Survey. The report, to be entitled Geohydrology of and Simulation of Ground Water Flow in the Valley Fill Deposits of the Ramapo River Valley. New Jersey, is to be published as U.S. Geological Survey Water Resources Investigations Report 904151. Raw data was obtained from the Survey concerning seepage losses of the Ramapo River in the vicinity of the public supply "Ford", "Bush" and "Soons" wellfields. The data shows stream losses measured at stations downstream of the wellfields. According to Mr. Brown, "there is no doubt that wellfields receive recharge from the river".

    2. Streamflow Source Zone

    The streamflow source zone is the upstream area of losing streams which flow into the recharge area. The Aquifer Service Area includes the Townships of Mahwah and Wayne and the Boroughs of Ramsey, Oakland, Franklin Lakes, Allendale and Pomptom Lakes in New Jersey. In New York, the Aquifer Service Area includes the Towns of Ramapo, Haverstraw, Orangetown and Clarkstown and the Villages of Hillburn, Suffern and Spring Valley and the Township of Stony Point.

    Because the US EPA determined that contaminants introduced in any of these areas have the potential to adversely affect the Ramapo River Basin Aquifer Systems, the designated Sole Source Aquifer includes the aquifer recharge areas and streamflow source areas encompassed by the Ramapo River Basin boundaries. The Project Review Area is defined as coincident with the boundaries of the Ramapo River Basin.

    E. Ground Water Use

    Table 1 shows the water suppliers, population served, and amount of water withdrawn from all sources in the Aquifer Service Area (ASA). For the New York area, the figures were acquired from the New York State Department of Health 1982 Atlas of Community Water System Sources and from the Orange County Department of Health. The total population residing within the aquifer service area is estimated at 300,000. The population dependent on ground water is estimated at 180,000. An average of 57% of the population depends on ground water for its public water supply. The current drinking water sources for the petitioned SSA aquifer service area include eighty percent (80%) public water supply coming from the petitioned aquifer and twenty percent (20%) coming from surface water.

    F. Ground Water Quality

    Water from the Precambrian gneiss is characteristically low in dissolvedsolids content (56124 mg/l), is soft to moderately hard (3094 mg/l) (milligrams per liter), and is acidic to neutral, with the pH ranging from 5.2 to 7.2. In comparison, water from the Brunswick Formation contains moderate amounts of dissolved solids (129278 mg/l), is moderately hard to very hard (89188 mgjl), is neutral to slightly alkaline, with the pH ranging from 7.1 to 8.1. Water from the Quaternary sand and gravel deposits contains moderate amounts of dissolved solids (113-215 mg/l), is generally moderately hard (75-155 mg/l), and is neutral to slightly alkaline, with a pH ranging from 6.8 to 7.7.


    The chemical and physical quality of surface water varies with the discharge of the stream, as well as with the geology of the drainage area. The relation of surface water quality to geology and ground water can be demonstrated by comparing the quality characteristics of the tributary streams with those of the various aquifers. The surface water from the area underlain by Precambrian rocks is low in dissolved solids concentration(42-50 mg/l), is very soft (20-23 mg/l), and slightly acid to neutral (pH 6.3-6.8) (Vecchioli and Miller, 1974). In contract, the water of streams draining Triassic and Quaternary rocks is higher in dissolved solids concentration (105-128 mg/l), is moderately hard (66-90 mg/l), and is neutral (pH 6.7-7.4) (Vecchioli and Miller, 1974). This comparison is very similar to the comparison made of the ground water from these rocks.

    III. Susceptibility to Contamination

    The Ramapo River Basin Aquifer Systems are vulnerable to contamination from many sources. The Ramapo River Basin Aquifer Systems are unconfined, or water-table aquifers, which makes them vulnerable to contamination. In addition, much of the soil overlying the valleyfill aquifer in the Ramapo and Mahwah Rivers valleys is highly permeable. Further, the hydraulic connection between the aquifer and the Ramapo River has been documented. The aquifer is naturally recharged by the river and recharge is also induced by pumpage. As such, the potential exists for incidents of surface water contamination to affect public supply wells tapping the Ramapo River Basin Aquifer Systems.

    Incidents of contamination have already occurred in the Ramapo River Basin. The Ramapo Landfill Site, an NPL site covers ninety-six acres and is located in Ramapo, New York. The landfill is located 2,500 feet northeast of the intersection of U.S. Routes 17 and 59, approximately 1,800 feet east of the Spring Valley Water Company wellfield. Ground water at the site was found to be contaminated with volatile organic compounds (VOCs) and heavy metals. Surface water was found to be contaminated with heavy metals and phenols. Leachate from the site was found to be contaminating Torne Brook, a tributary of the Ramapo River. In a separate incident, one of the public supply wells in the Village of Suffern, New York was closed and two other wells were restricted due to contamination with methyl chloroform found in the Village's water supply system.

    IV. Alternative Sources of Drinking Water

    There are shortterm supply systems designed to provide public water supply if an emergency should occur. An emergency system has been established by Spring Valley Water Company for its New York State service area. A similar system is being completed in New Jersey. Those systems are considered supplements which would provide no more than twenty percent (20%) of drinking water supplies to the area and are notviable substitutes for the ground water supply obtained from the Ramapo River Basin Aquifer Systems. The proposed Ambrey Pond Reservoir has been in the planning stage and has been given approval should the Spring Valley Water Company's demand reach 27.9 mgd. However, the reservoir is considered to be a supplement for the ground water obtained from the Ramapo Aquifer Systems and not a supplement.

    V. Summary

    Based upon the information presented, the Ramapo River Basin Aquifer Systems meets the technical requirements for SSA designation. More than fifty percent (50%) of the drinking water for the aquifer service area is supplied by the Ramapo River Basin Aquifer Systems. In addition, there are no economically feasible alternative drinking water sources which could replace the Ramapo River Basin Aquifer Systems. It is therefore recommended that the Ramapo River Basin Aquifer Systems be designated a SSA. Designation will provide an additional review of those projects for which Federal financial assistance is requested, and will ensure protection measures, incorporating state and local measures whenever possible, for only those projects which request Federal financial assistance.

    VI. Selected References

    1. Brown, A., 1992. Personal Communication. U.S. Geological Survey, Water Resources Division, Trenton New Jersey.

    2. Bugliosi, E.F., and R. Trudell, 1988. Potential Yields of Wells in Unconsolidated Aquifers In Upstate New York -- Lower Hudson Sheet. U.S. Geological Survey, Water Resources Investigations Report 874274, scale 1:250,000.

    3. Canace, R., and W. Hutchinson, 1989. Bedrock Topography and Profiles of Valley Fill Deposits in the Ramapo River Valley, New Jersey Geological Survey Map Series 886, 2 plates, scale 1:24,000.

    4. Moore, R.B., 1984. Ramapo River Mahwah River Area. In Atlas of Eleven Selected Aquifers in New York. U.S. Geological Survey Water Resources Investigations, OpenFile Report 82553, p. 6181.

    5. Moore, R.B., D.H. Caldwell, W.G. Stelz, and J.L. Belli, 1982. Geohydrology of the Valley Fill Aquifer in the Ramapo and Mahwah Rivers Area, Rockland County, New York. U.S. Geological Survey Open File Report 82114, 6 sheets, scale 1:24,000.

    6. Perlmutter, N.M., 1959. Geology and Ground Water Resources of Rockland County, New York. U.S. Geological Survey Bulletin GW 42, 129pp..

    7. Township of Mahwah, and Passaic River Coalition, 1991. Sole Source Designation for Ramapo Aquifer Systems, 23 pp..

    8. U.S. Army Corps of Engineers, 1983. New York District Interim Report on Flood Protection Feasibility, Ramapo and Mahwah Rivers, Mahwah, N.J. and Suffern, N.Y., Passaic River Basin, New Jersey and New York, Phase I General Design Memorandum, Main Report and Environmental Impact Statement.

    9. U.S. Environmental Protection Agency, Office of Ground Water Protection, 1987. Sole Source Aquifer Designation: Petitioner Guidance, 29pp. appendices.

    10. Vecchioli, J., and E.G. Miller, 1974. Water Resources of the New Jersey Part of the Ramapo River Basin. U.S. Geological Survey, Water Supply Paper, 76pp..

    VII. Table

    Table 1. Municipalities Dependent on the Ramapo River Basin Aquifer Systems

      Town Population Dependent Population
    New Jersey Township of Mahwah 16,278 100% 16,278
      Borough of Ramsey 13,224 100% (1) 13,224
      Borough of Oakland 12,716 100% 12,716
      Borough of Franklin Lakes 9,912 100% 9,912
      Borough of Allendale 5,908 100% (2) 5,908
      Borough of Pompton Lakes 5,467 100% 5,467
      Borough of Wayne 1,300 100% (3) 1,300
      Total New Jersey 64,805   64,805
    New York Hillburn Village 926 100% 926
      Town of Ramapo 36,111 100% 36,111
      Village of Suffern 10,794 100% 10,794
      Village of Sloatsburg 3,154 0% ----
      Town of Haverstraw 8,800 40% (6) 3,520
      Township of Stony Point 8,686 40% (6) 3,474
      Village of Tuxedo Park 809 0% (7) ----
      Town of Monroe 23,035 0% (7) -----
      Monroe Village 5,996 0% (7) ----
      Town of Woodbury 8,236 0% (7) ----
      Town of Blooming Grove 16,673 0% (7) ----
      Village of Spring Valley 20,537 50% (5,6) 10,269
      Harriman Village 796 0% (7) ----
      Tuxedo Town 3,023 0% (7) ----
      Town of Orangetown 34,998 50% (5,6) 17,999
      Town of Clarkstown 74,346 50% (5,6) 37,173
      Total New York 256,920   22,325
    Total in NY & NJ   321,725   321,725

    Total Population served: 184,571 or 57.4%
    (1) Purchase 40-50% of their water from Mahwah.
    (2) Purchase 60% of their water from Ramsey.
    (3) Calculated only to that portion of the Township of Wayne dependent on ground water and in the sub-basin.
    (4) Total population served is approximately 250,000 according to Spring Valley Water Company: USGS calculated population served at 81,600 for the Ramapo River-Mahwah River area in 1980.
    (5) From May through November approximately 80% of their water comes from the Lake Deforest Reservoir and approximately 20% from the Ramapo Aquifer System.
    (6) Estimate by Spring Valley Water Company.
    (7) Located in Orange County, which is sparsely developed, contains a few small surface reservoirs, and may have some private wells drilled into the rock.
    (8) Accounting for which drop of water originating from the Ramapo Aquifer and which from others is extremely difficult, if not impossible. The estimates have been provided by the Spring Valley Water Company.

    VIII. Figures

    Ramapo Figures 



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