4. Hydrology and Water Quality Overview

4.1 Introduction

Environmental Conservation Law Article 57 requires that the Central Pine Barrens (CPB) comprehensive land use plan be designed to preserve the ecology and ensure the high quality of groundwater within the CPB, and that preparation of the plan be based on previously undertaken and current ecological and groundwater studies (Sections 57-0121(1) and (5)). Information on such topics as CPB ground and surface water hydrology, water quality, and water supply pumpage was therefore compiled to meet this requirement. Although Article 57 does not specify that such information be included in the plan (see E.C.L. Section 57-0121(6)), a summary is presented here to allow a more complete understanding of plan derivation.

Hydrologic and water quality information is important to the planning process because it allows the development of conceptual, statistical, analytic, and numerical models of the ground and surface water systems, which, in turn, help in understanding how these systems work and provide a means for predicting system responses to future conditions. The following discussions identify the major types and sources of information that are applicable to the CPB planning process, and provide summaries of relevant data and concepts. Referenced sources include U.S. Geological Survey (USGS) studies, Brookhaven National Laboratory (BNL) and Suffolk County Department Health Services (SCDHS) monitoring data, and recent work by State University of New York (SUNY) at Stony Brook and SCDHS on the Peconic River and Estuary system.

4.2 Hydrogeology

Issues concerning surface water ecology and water supply generally involve the two uppermost major geologic units the upper glacial deposits, and the older, deeper deposits of the Magothy formation. However, sophisticated modeling of the hydrologic system also requires an understanding of the deeper formations; the bedrock, Lloyd Sand, and Raritan clay. (Figure 4-1). This section will focus on the shallowest units. Data and discussions on the deeper units can be found in De Laguna (1963), Jensen and Soren (1974), and Soren and Simmons (1987).

4.2.1 Ronkonkoma Moraine and Outwash Plains

The most prominent topographic feature of the CPB is the Ronkonkoma glacial moraine (Figure 4-2), which traverses the area west-east, bisecting the western portion, dipping south of Brookhaven National Lab, and treading along the northern portion of the South Fork. (Jensen and Soren 1974). The moraine influences surface drainage patterns, but is not a significant factor affecting groundwater flow. To the south of the moraine lies a relatively flat glacial outwash plain composed of sand and gravel that contains very little silt or clay; to the north lie a series of shallow basins (Selden, Manorville, Riverhead) filled with similar outwash deposits from both the Ronkonkoma moraine and the Harbor Hill moraine, which runs along the north shore. (De Laguna 1963). These highly permeable outwash deposits comprise the major portion of the upper glacial aquifer. (see Upper Glacial Aquifer, below). For a more detailed history of Long Island glaciation, see Sirkin (1994), and Sanders and Merguerian (1994).

4.2.2 Surficial Silt and Clay Deposits

At the close of the glacial period, mud and silts are believed to have been deposited in swamps and lakes in the low lying area between the moraines. (De Laguna 1963; Warren et al., 1968). This deposition, in combination with the reworking of wind-eroded glacial material (loess), produced shallow silt and clay deposits that now are found locally, particularly in lowlands along the Peconic River and in minor headwater tributaries. These deposits are at most 5 to 10 feet thick, and are generally found less than 30 feet below grade. They retard recharge, forming swampy areas or ponds that persist even when the surrounding water table declines, thus creating perched or semi-perched surface water systems.

Figure 4-1: Hydrogeologic Cross Section D-D'
(Please see the printed version of the Plan for this illustration.)

It is not known whether such deposits underlie all of the freshwater ponds and wetlands in the headwater areas of the Peconic and Carmans Rivers.

4.2.3 Glacial Clay Units

The stratigraphy of the upper glacial deposits is complex, and includes a number of local, and possibly subregional, clay units that affect groundwater movement. Within the sequence of glacially-derived sediments is a thick clay unit that has been identified in the western portion of the CPB area as Smithtown Clay. Beginning at elevations ranging from 10 to 70 feet above sea level, it extends downward in thicknesses of 30 to 100+ feet. (Krulikas and Koszalka 1983). This unit is believed to have been deposited in a lake or series of lakes that formed north of the Ronkonkoma moraine, and the sequence "outwash-clay-outwash" is typical of much of the intermorainal area as far east as the North Fork . (Long Island Regional Planning Board (LIRPB) 1992). At Manorville, a clay unit (possibly related to the Smithtown Clay) was found to extend from sea level to a depth of -30 to -60 feet, although it was not identified below BNL. (De Laguna 1963). Where present, these clays can be expected to impede the downward flow of groundwater, resulting in water table "mounding," and may also confine deeper groundwater in areas such as the central and lower Peconic River valley. (see Upper Glacial Aquifer Flow and Magothy Aquifer Flow, below).

4.2.4 Upper Glacial Aquifer

The sequence of glacial deposits within the CPB area is generally on the order of 200 feet thick. Exceptions are found on the Ronkonkoma moraine, and in areas where the Magothy was eroded, including north-central Brookhaven, where 600-700 feet of glacial deposits fill a northeast-southwest treading valley running from Rocky Point to Centereach. (Koszalka 1984; Soren and Simmons 1987). The saturated portion of this sequence, comprising the upper glacial aquifer, is generally on the order of 150 feet thick below the outwash plain south of the Ronkonkoma moraine, but much greater to the north where the Magothy was eroded. (see above). The combination of high aquifer permeability and moderate thickness limits the effects of glacial pumping wells on water table elevations; for example, a typical supply well extracting 1,000 gallons per day (gpm) would produce calculated drawdowns of 2 feet at a distance of about 300 feet, 1 foot at a distance of about 1,000 feet, and one-half foot at a distance of about 2,000 feet. (SCDHS 1987). It should be noted, however, that even such modest reductions in water table elevations, when they occur long-term, may have negative impacts on sensitive wetland ecosystems. (SCDHS 1987).

4.2.5 Gardiners Clay Unit

The Gardiners Clay unit is generally present as a 10-20 foot thick mixture of clay and sand lying about 100 feet below sea level separating glacial and Magothy deposits throughout much of the region south of the Ronkonkoma moraine. (De Laguna 1963). De Laguna also identified a clay unit below BNL as being Gardiners, although this determination was not reflected in later USGS reports. (Jensen and Soren 1974; Soren and Simmons 1987). In any case, these clays are not believed to be a significant hydrologic barrier to the recharge of the Magothy from the upper glacial aquifer within the CPB area. (De Laguna 1963).

Figure 4-2: Glacial Moraines and Basins
(Please see the printed version of the Plan for this illustration.)

4.2.6 Magothy Aquifer

Below the southern portions of the CPB, the deposits of the Magothy formation are found at 100-150 feet below sea level and range in thickness from 800 to 900 feet. In the northwestern portion of the CPB, where the Magothy surface was eroded, the top surface of the Magothy is found as deep as 500-600 feet below sea level, and may be only 100 feet thick. (Jensen and Soren 1974; Soren and Simmons 1987). Magothy deposits consist primarily of clayey sands or sandy clays, which have lower hydraulic conductivities than the overlying glacial deposits. (De Laguna 1963). The lower 100-200 feet of the Magothy generally consists of coarse sands and gravel beds with higher conductivities. (Jensen and Soren 1974). Localized clay lenses, some as thick as 50 feet, are believed to be present throughout the formation, but are not believed to be a major barrier to groundwater movement. (De Laguna 1963).

4.3 Ground and Surface Water Hydrology

This section describes the various components of the hydrologic cycle: rainfall, recharge, and stream discharge as well as the movement of groundwater through the aquifer system.

4.3.1 Precipitation

All naturally occurring fresh water in the CPB area, as in all of Suffolk County, originates as precipitation. Long-term (40-year) average precipitation rates for Brookhaven National Lab (Upton) have been reported as 46.3 inches per year for 1943-1982 (Krulikas 1986) and 48.4 inches per year for 1950-1989. (Naidu 1992). Annual rates generally decrease by a few inches from the center of the island shoreward, and from west to east, possibly due to influences of land topography (e.g., the Ronkonkoma moraine) and the prevailing west to east direction of wind and storm movement. (see Miller and Frederick 1969). Precipitation at BNL reached a high of 68.7 inches in 1989, and a low of 31.8 inches (or 34% below the long-term average) during the drought in 1965. Lows approaching those of 1965 were also experienced in 1980 and 1985. (Naidu 1992). Monthly precipitation rates are fairly consistent throughout the year, so that no distinct wet or dry seasons are distinguishable. March, August, November, and December are the wettest months at Upton, averaging about 4.5 inches, while June, July, and September are the driest months, averaging between 3 and 3.5 inches. (Krulikas 1986).

4.3.2 Recharge

The amount of precipitation recharged to the aquifer system is reduced by the amount lost to evaporation and plant transpiration (cumulatively referred to as evapotranspiration) and by the amount lost through direct runoff to streams or tidal water bodies. Evapotranspiration has been calculated, using the Thornthwaite method for average precipitation conditions, to range from 22.4 inches per year for shallow-rooted vegetation in sandy loam soils in Riverhead, to 23.9 inches per year, for deep-rooted vegetation in silty loam soils in Upton. (Peterson 1987). Direct runoff for the CPB area has been estimated to be only about 0.5 inches per year (Krulikas 1986), so that recharge to the aquifer system under average precipitation conditions is calculated to range from 22 to 26 inches per year (or 1.05 to 1.24 million gallons per day (mgd) per square mile), with recharge patterns reflecting precipitation patterns. (Peterson 1987). Total recharge for the 100,000 acre (156 square mile) CPB area, therefore, is on the order of 164-193 mgd.

4.3.3 Hydrogeologic Zones

The CPB area encompass regions of deep aquifer recharge on both sides (north and south) of the groundwater divide, which traverses central Brookhaven and splits into North and South Fork branches, beginning in the area near the northwest corner of Brookhaven National Lab, and extending eastward. (Figure 4-3; see Upper Glacial Aquifer Flow, below). The boundaries of the CPB area approximate those of deep-flow Hydrogeologic Zone III, with the exception of the westernmost portion of the zone, as defined by the 208 Study (LIRPB, 1978) and later delineated by the SCDHS for the Suffolk County Sanitary Code (Figure 4-3). The Peconic River and upper reaches of the Carmans River drain the east-central and south-central portions of Hydrogeologic Zone III, respectively, and represent subsystems with shallow flow components within the deep recharge area. The CPB also includes areas surrounding the lower freshwater portion of the Carmans River, which extends into shallow-flow Hydrogeologic Zone VI.

4.3.4 Water Table and Depth to Water

The water table within the CPB reaches a maximum elevation of 50-55 feet above mean sea level along the divide in the westernmost portion of the area, and drops off to the north, south, and east, being about 25-35 feet at North Country Road (Route 25A), 40-45 at the LIE in Medford, 35-50 feet at BNL, and generally less than 30 feet on the South Fork. Long-term average annual water table fluctuations due to seasonal variations in precipitation are generally less than a few feet; however, declines as great as 4 feet (10%) from the long-term average were observed at BNL during the 1960s drought. (Krulikas 1986). Depths to the water table from land surface range from over 150 feet along the moraine, to about 80 feet north of the main divide, and 40 feet on the southern outwash plain and between the divides, declining to less than 10 feet in areas near the Peconic River and drainage ways at its headwaters. (Wallace et al., 1968). Maps of areas with less than 4 feet from land surface to seasonal high water table elevations were prepared and used in CPB Plan preparation.

4.3.5 Upper Glacial Aquifer Flow

The rate of vertical flow in the upper glacial aquifer is greatest at about 6 feet per year near the divides, and decreases to a negligible amount at the shoreward boundaries of deep-flow Hydrogeologic Zone III. (SCDHS 1987). Horizontal groundwater flow velocities within the upper glacial aquifer are generally on the order of one-half foot per day near the main divide and on the South Fork portion of the CPB, based on water table gradients of about 2-3 feet per mile, and about one foot per day for most other portions, based on a gradient of 5 feet per mile.

The directions of horizontal flow follow water table gradients, and are primarily north and south on the respective sides of the main groundwater divide, with a small easterly component throughout most of the CPB (except directly to the east of the Carmans River, where flow is south-southwest). The influence of the Peconic River extends westward just beyond Brookhaven National Lab, where the main groundwater divide splits into a northern branch that approximately bisects the Navy's Calverton facility, and a southern branch that generally follows the topographic high formed by the Ronkonkoma moraine. (Figures 4-2 and 4-3; see Jensen and Soren 1974; LIRPB 1992). Most of the recharge in the region between the divides discharges to the Peconic river via shallow flow. The shallow-flow groundwater contributing area of the Peconic River was delineated by Krulikas (1986), and his work was utilized by the SCDHS for the Brown Tide Comprehensive Assessment and Management Program (BTCAMP). (SCDHS 1992).

4.3.6 Magothy Aquifer Flow

Recharge of the Magothy from the upper glacial aquifer is greatest near the main groundwater divide, and gradually decreases seaward, until it is negligible at the deep recharge zone boundaries. Groundwater within the Magothy moves slower than in the upper glacial aquifer. It moves generally 0.1-0.2 feet per day even though head gradients are similar which reflects the lower hydraulic conductivity of the deeper unit. Residence times are thus much greater for the Magothy, taking hundreds of years for water recharged near the divide to be discharged at the shoreline. (Buxton and Modica 1992). The Magothy has an easterly component of flow below the entire CPB area, and Magothy water contributes to the underflow to the Peconic Estuary east of the Peconic River. (SCDHS 1992).

Figure 4-3: Hydrogeologic Zones and Groundwater Divides
(Please see the printed version of the Plan for this illustration.)

4.3.7 Water Supply Pumpage

Seven Suffolk County Water Authority (SCWA) public water supply wellfields are located within the CPB boundaries (Figure 4-4): Bailey Road (Middle Island), Bridgewater Drive (Ridge), William Floyd Parkway (Yaphank), Country Club Drive (Moriches), Moriches- Riverhead Road (Riverside), Old Country Road (Westhampton), Spinney Road (East Quogue). Pumpage for 1992, which was a year of average precipitation, totaled about 3 mgd, of which 2.6 mgd or 87%, was pumped from the upper glacial aquifer. The largest public pumpage occurred at the William Floyd Parkway wellfield, where two glacial wells produced 0.8 mgd, and one Magothy well produced 0.2 mgd. Other withdrawers within the CPB included Brookhaven National Lab (4.2 mgd), the Hampton Bays Water District (Bellows Road wellfield, 0.46 mgd), Calverton Hills Association (0.05 mgd), and Grumman-Calverton (0.2 mgd, estimated). Another 6.8 mgd was pumped in 1992 by the 13 public supply wellfields located just downgradient of the CPB area, which probably pump water originating within the CPB. (Figure 4-4). Total withdrawals from the CPB area in 1992, therefore, were as much as 14.5 mgd, which is equivalent to about 8% of recharge, but only a small percentage of this pumpage is believed to be used consumptively. Most pumpage is returned to the aquifer system in the general area from which it was pumped, although in some cases this may be outside (south) of the CPB area boundary. The largest consumptive use occurs at BNL, where on the order of 1 mgd of cooling water is lost to the atmosphere. (Naidu, 1993).

Figure 4-4: Public Water Supply Wellfields
(Please see the printed version of the Plan for this illustration.)

4.3.8 Streamflow

A significant portion (on the order of 25%) of the precipitation recharged within the CPB area leaves the groundwater system via streamflow, primarily in the Peconic and Carmans Rivers. The Peconic River system derives flow from areas as far west as BNL, and perched marshlands located just west of William Floyd Parkway, although this flow across the western portion of the lab is intermittent, usually occurring only after heavy rainfalls or during times of high water table elevations. Streamflow at the downstream (eastern) boundary of BNL is often minimal (Naidu 1992), but overall has been estimated to average 0.6 mgd. (Warren et al., 1968). Farther east, at Wading River-Manorville Road, flow averages around 2 mgd, but has been measured to vary from 1 to 28 mgd, reflecting water table fluctuations and the intensity of rainfall events. (Warren et al., 1968). Flow on the lower Peconic River, as measured at the USGS gauging station located 0.4 miles west of Riverhead, has ranged from 10.4 mgd (1966) to 43.9 mgd (1984), with a long-term (1942-92) average of 24.0 mgd (Spinello et al., 1993); an estimated 1.4 mgd, or 6% of the long-term average flow, is runoff. (SCDHS 1987). At the mouth of the river, just east of County Route 105, the average total freshwater flow rate is estimated to be 34 mgd, which includes 14 mgd of groundwater estimated by the USGS to be discharged to the river downstream of the USGS gauging station. (SCDHS 1992).

The Carmans River flows south through a gap in the Ronkonkoma moraine from its headwaters located in the area of Artist Lake in Middle Island. (see Figure 4-2). It reaches the dividing line between Hydrogeologic Zones III and VI at Yaphank, about six miles from its headwaters, with flows measured at the USGS gauging station ranging from 8.3 mgd (1967) to 24.3 mgd (1979), and a long-term (1942-92) average of 15.6 mgd. (Spinello et al., 1993). Farther south, the rate of discharge of groundwater to the river increases as it traverses the outwash plain, and by the time the river reaches the boundary of the CPB at Route 27, some 12 miles south of its starting point, the average flow rate has increased to about 35 mgd. The southernmost 3 miles of the river are tidal, where it gains an estimated additional 11.5 mgd of groundwater, bringing the total freshwater discharge into Bellport Bay at the mouth of the river to 46.5 mgd. (Warren et al., 1968).

4.4 Pond and Wetland Hydrology

The general status of knowledge concerning wetland hydrology has been characterized as "inadequate" (Kusler 1987), and this characterization holds true for the wetlands of the CPB area, where no systematic investigation of each individual wetland and its relation to groundwater has been made. Five of the six dominant surface hydrologic cover types associated with wetlands in glaciated regions (Hollands 1987) have been identified in the CPB area: open water bodies (ponds), vegetated wetlands other than cranberry bogs, inactive cranberry bogs, perennial streams, and ephemeral streams. Only active cranberry bogs are no longer present. Many of these wetlands have been altered by man through the creation of small channels (such as those interconnecting the Manorville ponds), the erection of small dikes and embankments to create cranberry bogs, and the construction of mill dams on the Peconic and Carmans Rivers to create artificial lakes.

Many of the CPB wetlands are found in kettle holes, which were formed by the melting of detached, buried blocks of glacial ice. These steep-sided depressions generally have no drainage outlet, and the wetlands at their bottoms can be either perched or groundwater fed. The rates of sediment input from runoff and dust, and the creation of organic sediments due to biological activity within CPB wetlands without surface outlets, can be assumed to have been minimal prior to development, or they would have long since filled in. Wetlands without surface outlets may both receive and discharge to groundwater, with a net balance favoring discharge, since rainfall generally exceeds open water evaporation rates for Long Island, estimated to be 34 inches per year. (Pluhowski and Kantrowitz 1964). Where stormwater runoff is directed into such ponds, they may rise above the water table and create small, localized recharge mounds. Perched and semi-perched systems, including ephemeral (post-precipitation) streams, have been identified around BNL. (Warren et al., 1968). These systems lie above the water table and can drain in any direction, independent of underlying groundwater flow.

4.5 Ground and Surface Water Quality

This section describes the known quality of water throughout the various stages of the hydrologic cycle within the CPB, beginning with input from rainfall, followed by movement through surface wetlands and groundwater, and concluding with output as streamflow and underflow.

4.5.1 Precipitation

Precipitation inputs to the CPB's hydrologic system are related to natural processes and to recent, anthropogenic sources such as fossil fuel combustion emissions and agricultural fertilizers, which can add nutrients and various contaminants to fragile wetland ecosystems and groundwater. Precipitation on Long Island, as elsewhere, is naturally acidic, but has been made more so by air pollution. pH values now generally range from 3.5 to 6 (Spinello et al., 1983), with a long-term (1965-89) average at BNL of 4.3. (Schoonen and Brown 1994). The input of plant nutrients is of greater concern. While concentrations of phosphorus are generally negligible (<0.1 ppm; Spinello et al., 1983), nitrogen, in the form of nitrate and ammonia, was found at BNL during 1969-1973 to range from non-detect to 2.8 ppm, with an average of 0.5 ppm. (Frizzola and Baier 1975). More recent data (1982-89) from BNL also indicate an average total nitrogen concentration of about 0.5 ppm (Schoonen and Brown 1994). Data from the New Jersey Pinelands (Morgan and Good 1988) and recent work by SUNY at Stony Brook with data collected at BNL during 1986-1989 (Proios and Schoonen 1994) demonstrated a distinct difference between storms originating over the ocean which contribute sea salt aerosols containing ions of sodium, chloride, magnesium and storms coming across the continent which also contain nitrate, ammonia, sulfate, potassium, and calcium ions from soil and mineral dust, agricultural activities, and industrial air pollution. These relationships have been used by Stony Brook researchers to estimate atmospheric loadings to the Peconic River watershed based on the frequency of various storm types. (Proios and Schoonen 1994).

4.5.2 Groundwater Quality

Shallow groundwater within the CPB area has a wide range of quality conditions, reflecting the nature and extent of local development. At one extreme is near "pristine" water found in undeveloped areas; it cannot be called truly pristine due to the low levels of contamination now introduced by rainwater. Such water is naturally acidic, and very low in plant nutrients such as nitrate-nitrogen (0.02-0.3 ppm), ammonia-nitrogen (0.02-0.2), sulfate (5-6 ppm), and total phosphorus (0.01-0.05 ppm), since these are readily taken up by vegetation in the nutrient-poor CPB ecosystem. It is also very low in dissolved minerals such as potassium, calcium, and magnesium. (Soren 1977; SCDHS unpublished data). Iron and manganese, however, are sometimes found at concentrations exceeding drinking water standards, although the low dissolved oxygen conditions associated with high metals concentrations are generally limited to deeper parts of the glacial aquifer and the Magothy aquifer.

At the other quality extreme are areas within or adjacent to major facilities such as BNL, Grumman, and Westhampton Airport, and areas near smaller commercial establishments such as gas stations along Route 25, where significant localized contamination of groundwater with petroleum products and/or organic solvents has occurred. Radiological impacts have been detected southeast of BNL, where a number of private wells have been impacted by tritium discharged by the Lab's sewage treatment plant, although at levels within the drinking water limit. (Naidu 1992).

Groundwater quality below residential areas reflects the impacts of sanitary sewage and lawn chemicals, which on occasion have contaminated shallow private wells beyond drinking water standards in more densely developed areas. Overall, however, residential development has not caused significant degradation of water quality in terms of water supply, and public supply wells have generally continued to produce water of excellent quality (i.e., nitrate-nitrogen less than 1-2 ppm, with no detectable organics). Exceptions have occurred in agricultural areas, where fertilizers and pesticides have leached to groundwater. (LIRPB 1992). For example, the SCWA's shallow glacial well at Spinney Road (East Quogue), located immediately downgradient of a farming area, has had nitrate-nitrogen over the 10 ppm drinking water standard, and is currently blended with the deeper, less contaminated glacial well water. Both have aldicarb concentrations high enough to prompt the voluntary installation of Granular Activated Carbon (GAC) filters. Nutrients and pesticides related to turf management may also be a problem in some areas. (LIRPB 1992). For example, tetrachloroterephthalic acid (TCPA), a breakdown product of the herbicide Dacthal, has been detected in a glacial well at SCWA Bridgewater Drive (Ridge), and the SCWA's two glacial wells at Country Club Drive (Moriches) have nitrate-nitrogen in the 3-4 ppm range, with elevated sulfates, probably related to current turf management and past farming activities in nearby upgradient areas. (Figure 4-4).

4.5.3 Pond and Wetland Water Quality

Chemical concentrations in the ponds and other wetlands of the CPB area have not been comprehensively documented, but present evidence indicates that these systems are similar to those in the New Jersey Pinelands. Specifically, they are highly acidic and nutrient deficient when in the undisturbed state. In New Jersey, phosphorus appears to be the primary nutrient that limits biological productivity in even marginally disturbed systems, while both phosphorus and nitrogen may limit productivity in undisturbed, pristine systems. (Morgan and Philipp 1986; Schoonen and Brown 1994). The sources, quantities, and significance of human inputs are now being investigated, including atmospheric pollution and stormwater runoff that may contain road salts, fertilizers, and pesticides. Septic system effluents and fertilizers may also be a source of nitrogen to groundwater-fed wetlands, but are probably not a significant source of phosphorus, since phosphate is relatively immobile in groundwater. (De Laguna 1964; NYSDOH 1969). Hydrologic factors are also believed to affect wetland water quality and ecology, including the presence of surface water inlets and outlets, the relationship to the water table, which may control the routes of contaminant input and the response to rainfall variations, and the water depth and bottom sediment composition, which control plant species, and therefore waterfowl populations and other fauna.

4.5.4 River and Underflow Water Quality

Water quality conditions in the Peconic and Carmans Rivers are monitored by the USGS, SCDHS, and BNL, and have recently been the subject of investigation by SUNY at Stony Brook. (Schoonen and Brown 1994). The average total nitrogen concentration measured by SCDHS at the USGS gauging station on the Peconic River during 1988-1990 was 0.5 ppm, with nitrate and organic matter contributing approximately equal amounts of nitrogen to annual loadings. A distinct seasonal variability in nitrate-nitrogen concentrations was observed, however, reaching as high as 0.6 ppm during the winter months when biological uptake is minimal. (SCDHS 1992). Total phosphorus at the gauging station during the same time period averaged 0.1 ppm. (SCDHS 1992). Traces of freon and 1,1,1-trichloroethane have also been found routinely in the river. (SCDHS unpublished data).

While these concentrations are relatively low, they do not reflect pristine conditions, and it must be emphasized that the river is a major source of nutrients to environmentally-stressed Flanders Bay, even with the relatively low levels of current development within the Peconic River watershed. (SCDHS 1992). The nutrient loadings derived from the estimated 14 mgd of shallow groundwater gained by the Peconic River downstream of the gauge are also significant, given the higher levels of development and agricultural activity in this area. (SCDHS 1992). The underflow that discharges directly to Flanders Bay has also experienced significant degradation due to nitrogen loading from agriculture and development (SCDHS 1992), although the contribution of Magothy water to underflow pollution loadings is probably minimal, given the present high quality of Magothy water emanating from the CPB area.

Evaluations of the significance of pollution sources within the Peconic River watershed are ongoing by the SCDHS, BNL, and SUNY at Stony Brook. Chemical budgets developed by Stony Brook and water quality data collected at multiple points along the river implicate road salts, fertilizers, and lime used on turf as factors in river quality degradation. (Schoonen and Brown 1994). Other Stony Brook data indicate that inorganic chemical concentrations in the headwaters of the Peconic River can increase after a rainfall, while those near the mouth decrease; the reasons for this response are as yet unknown. (Choynowski and Schoonen 1994). Based on a BTCAMP investigation of the relationship between groundwater and surface water quality in the Peconic River and Flanders Bay areas, the SCDHS has proposed stringent development controls in the Peconic River groundwater-contributing area. This includes limiting new residential development to no less than two acres per dwelling unit, or its equivalent in the remaining, undeveloped portions of the Peconic River groundwater shed, and establishing a policy of no net increases in nitrogen loading from point sources. (SCDHS 1992).

Water quality data collected by the SCDHS at the USGS gauging station on the Carmans River at Yaphank indicate total nitrogen concentrations are in the 1-2 ppm range, which are higher than those observed for the Peconic River. (Spinello et al., 1993). Intermittent traces of 1,1,1- trichloroethane have also been detected. (SCDHS unpublished data). Thus the Carmans River represents a significant source of nutrients, and possibly other contaminants, into poorly-flushed Bellport Bay.

4.6 Bibliography: Hydrology and Water Quality Overview

Brookhaven National Laboratory. Site Environmental Report for Calendar Year 1991. Safety and Environmental Protection Division. Upton, New York, September 1992.

Burton, Herbert T. and Edward Modica. "Patterns and Rates of Ground-Water Flow on Long Island, New York." Ground Water 30:6 (November-December 1992): 857-866.

Choynowski, John P. and Martin A. A. Schoonen. A Study of the Effects of a Rain Storm Upon the Major Chemical Constituents of the Peconic River, Long Island, New York. Earth and Space Science Department, SUNY Stony Brook, undated.

De Laguna, Wallace. "Geology of Brookhaven National Laboratory and Vicinity," Suffolk County, New York. U.S. Geological Survey Bulletin 1156-A, 1963.

Flipse, William J. Jr., Brian G. Katz, Juli B. Lindner and Richard Markel. "Sources of Nitrate in Ground Water in a Sewered Housing Development, Central Long Island, New York." Ground Water 22:4 (July-August 1984): 418-426.

Frizzola, John A. and Joseph H. Baier. "Contaminants in Rainwater and Their Relation to Water Quality." Water & Sewage Works (August 1975): 72-75; (September 1975): 94-95.

Hollands, Garrett G. "Hydrogeologic Classification of Wetlands in Glaciated Regions." In Proceedings of the National Wetland Symposium on Wetland Hydrology. Association of State Wetland Managers, 26-30. Berne, New York, 1987.

Jensen, H. M. and Julian Soren, "Hydrogeology of Suffolk County, Long Island, New York." U.S. Geological Survey Hydrologic Investigations Atlas HA-501, 1974.

Koszalka, Edward J. "Geohydrology of the Northern Part of the Town of Brookhaven, Suffolk County, New York." U.S. Geological Survey Water-Resources Investigations Report 83-4042, 1984.

Krulikas, Richard K. "Hydrologic Appraisal of the Pine Barrens, Suffolk County, New York." U.S. Geological Survey Water-Resources Investigations Report 84-4271, 1984.

Krulikas, Richard K. and Edward J. Koszalka. "Geologic Reconnaissance of an Extensive Clay Unit in North-Central Suffolk County, Long Island, New York." U.S. Geological Survey Water-Resources Investigations Report 82-4075, 1983.

Kusler, Jon. "Hydrology: An Introduction for Wetland Managers." In Proceedings of the National Wetland Symposium on Wetland Hydrology. Association of State Wetland Managers, 4-24 Berne, New York (September 1987).

Long Island Regional Planning Board, The Long Island Comprehensive Special Groundwater Protection Area Plan. Division of Environmental Quality. Hauppauge, New York, 1992.

Miller, J. F. and R. H. Frederick. "The Precipitation Regime of Long Island, New York." U.S. Geological Survey Professional Paper 627-A, 1969.

Morgan, Mark D. and Ralph E. Good. "Stream Chemistry in the New Jersey Pinelands: The Influence of Precipitation and Watershed Disturbance." In Water Resources Research 24:7 (July 1988): 1091-1100.

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