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At least 55 records · Page 3Linked to original sources
USGS2003

Trends in nitrogen concentration and nitrogen loads entering the South Shore Estuary Reserve from streams and ground-water discharge in Nassau and Suffolk counties, Long Island, New York, 1952–97

The 13 major south-shore streams in Nassau and Suffolk Counties, Long Island, New York with adequate long-term (1971-97) water-quality records, and 192 south-shore wells with sufficient water-quality data, were selected for analysis of geographic, seasonal, and long-term trends in nitrogen concentration. Annual total nitrogen loads transported to the South Shore Estuary Reserve (SSER) from 11 of these streams were calculated using long-term discharge records. Nitrogen loads from shallow and deep ground water also were calculated using simulated ground-water discharge of 1968-83 hydrologic conditions. Long-term declines in stream discharge occurred in East Meadow Brook, Bellmore Creek and Massapequa Creek in response to extensive sewering in Nassau County. The smallest longterm annual discharge to the SSER was from the westernmost stream, Pines Brook, which is in an area in which the water table has been lowered by sewers since 1952. The three largest average annual discharges to the SSER were from the Connetquot River, Carlls River, and Carmans River in Suffolk County; the discharges from each of these streams were at least twice those of the other streams considered in this study. Total nitrogen concentrations in streams show a geographic trend with a general eastward increase in median total nitrogen concentration in Nassau County and a decreasing trend from Massapequa Creek eastward into Suffolk County. Total nitrogen concentrations in streams generally are lowest during summer and highest in winter as a result of seasonal fluctuations in chemical reactions and biological activity. The greatest seasonal difference in median total nitrogen concentration was at Carlls River with values of 3.4 and 4.2 mg/L (milligrams per liter) as N during summer (April through September) and winter (October through March), respectively. Streams affected by the completion of sewer districts show long-term (1971-97) trends of decreasing total nitrogen concentration and streams showing an increase in total nitrogen concentration are in unsewered areas with increased urbanization. Discharges from shallow ground water (upper glacial aquifer) and deep ground water (upper part of Magothy aquifer) were simulated from a ground-water-flow model calibrated to steadystate (1968-83) conditions. Simulated discharges from shallow-ground-water system in Nassau County were 10,700 Mgal/yr (million gallons per year) or 40,500,000 m 3 /yr (cubic meters per year), and those from Suffolk County were 52,300 Mgal/yr or 198,000,000 m 3 /yr. Discharges from deep-ground-water system in Nassau County were 4,900 Mgal/yr or 18,500,000 m 3 /yr, and those in Suffolk County were 12,700 Mgal/yr or 48,200,000 m 3 /yr. Ground-water concentrations of nitrogen decrease with depth and from west to east. The shallow ground water median nitrogen concentration for each county was determined using 1,155 samples collected at 167 shallow wells (125 feet deep or less) within 1 mile of the shore. The deep ground water median nitrate concentration (nitrate represented almost all of the total nitrogen) for each county was determined using 112 samples collected at 25 deep wells (greater than 125 feet deep) within 1 mile of the shore. The median nitrogen concentration for the shallow and median nitrate concentration for the deep ground water in Nassau County were 3.85 and 0.15 mg/L as N, during 1952–97; the corresponding concentrations for Suffolk County were 1.74 and <0.10 (less than 0.10) mg/L as N, during 1952–97. Nitrogen loads discharged from streams to the SSER for each year during 1972–97 were calculated as the annual total nitrogen concentration multiplied by the annual discharge. These values were calculated only for the seven streams for which sufficient data were available. The largest long-term (1972–97) average annual nitrogen load from Carlls River was 104 ton/yr or 94,300 kg/yr—about twice that of Connetquot River (54 ton/yr or 48,900 kg/yr) and over three times that of Carmans River (33 ton/yr or 29,900 kg/yr). The smallest annual mean nitrogen load was from Pines Brook, which has the lowest annual mean discharge of all streams analyzed. The nitrogen load carried to the SSER by ground-water discharge in shallow-ground-water system in Nassau and Suffolk Counties was calculated as the simulated discharge for each county multiplied by the respective median nitrogen concentration, and loads from deep-ground-water system were calculated as the simulated discharge for each county multiplied by the respective median nitrate concentration. All discharges were obtained from the U.S. Geological Survey's Long Island ground-water-flow model. The resultant nitrogen loads discharged to the SSER from shallow ground water were 172 ton/yr (156,000 kg/yr) from Nassau County and 380 ton/yr (345,000 kg/yr) from Suffolk County; equaling 552 ton/yr entering the SSER. Those from deep ground water were 3 ton/yr (2,700 kg/yr) from Nassau County and <0.5 ton/yr (480 kg/yr) from Suffolk County; equaling about 3.5 ton/yr entering the SSER. The sum of both stream loads and groundwater loads results in the total load to the SSER. The largest calculated total nitrogen load entering the SSER from both streams and ground water occurred in 1979 with a total load of 1,260 ton/yr (1,140,000 kg/yr). The smallest calculated nitrogen load entering the SSER occurred in 1995 with a total load of 725 ton/yr (658,000 kg/yr).

New York↗
USGS2002

Estimating state-transition probabilities for unobservable states using capture-recapture/resighting data

Temporary emigration was identified some time ago as causing potential problems in capture-recapture studies, and in the last five years approaches have been developed for dealing with special cases of this general problem. Temporary emigration can be viewed more generally as involving transitions to and from an unobservable state, and frequently the state itself is one of biological interest (e.g., 'nonbreeder'). Development of models that permit estimation of relevant parameters in the presence of an unobservable state requires either extra information (e.g., as supplied by Pollock's robust design) or the following classes of model constraints: reducing the order of Markovian transition probabilities, imposing a degree of determinism on transition probabilities, removing state specificity of survival probabilities, and imposing temporal constancy of parameters. The objective of the work described in this paper is to investigate estimability of model parameters under a variety of models that include an unobservable state. Beginning with a very general model and no extra information, we used numerical methods to systematically investigate the use of ancillary information and constraints to yield models that are useful for estimation. The result is a catalog of models for which estimation is possible. An example analysis of sea turtle capture-recapture data under two different models showed similar point estimates but increased precision for the model that incorporated ancillary data (the robust design) when compared to the model with deterministic transitions only. This comparison and the results of our numerical investigation of model structures lead to design suggestions for capture-recapture studies in the presence of an unobservable state.

Long Island↗
USGS2002

Aquifer geochemistry and effects of pumping on ground-water quality at the Green Belt Parkway Well Field, Holbrook, Long Island, New York

Geochemistry, microbiology, and water quality of the Magothy aquifer at a new supply well in Holbrook were studied to help identify factors that contribute to iron-related biofouling of public-supply wells. The organic carbon content of borehole sediments from the screen zone, and the dominant terminal electron-accepting processes (TEAPs), varied by depth. TEAP assays of core sediments indicated that iron reduction, sulfate reduction, and undetermined (possibly oxic) reactions and microbial activity are correlated with organic carbon (lignite) content. The quality of water from this well, therefore, reflects the wide range of aquifer microenvironments at this site. High concentrations of dissolved iron (3.6 to 6.4 micromoles per liter) in water samples from this well indicate that some water is derived from Fe(III)-reducing sediments within the aquifer, but traces of dissolved oxygen indicate inflow of shallow, oxygenated water from shallow units that overlie the local confining units. Water-quality monitoring before and during a 2-day pumping test indicates that continuous pumping from the Magothy aquifer at this site can induce downward flow of shallow, oxygenated water despite the locally confined conditions. Average concentrations of dissolved oxygen are high (5.2 milligrams per liter, or mg/L) in the overlying upper glacial aquifer and at the top of the Magothy aquifer (4.3 mg/L), and low ( < 0.1 mg/L) in the deeper, anaerobic part of the Magothy; average concentrations of phosphate are high (0.4 mg/L) in the upper glacial aquifer and lower (0.008 mg/L) at the top of the Magothy aquifer and in the deeper part of the Magothy (0.013 mg/L). Concentrations of both constituents increased during the 2 days of pumping. The δ 34 S of sulfate in shallow ground water from observation wells (3.8 to 6.4 per mil) was much heavier than that in the supplywell water (-0.1 per mil) and was used to help identify sources of water entering the supply well. The δ 34 S of sulfate in a deep observation well adjacent to the supply well increased from 2.4 per mil before pumping to 3.3 per mil after pumping; this confirms that the pumping induced downward migration of water. The lighter δ 34 S value in the pumped water than in the adjacent observation well probably indicates FeS 2 oxidation (which releases light δ 34 S in adjacent sediments) by the downward flow of oxygenated water.

New York↗
USGS2002

History and hydrologic effects of ground-water use in Kings, Queens, and western Nassau Counties, Long Island, New York, 1800's through 1997

Ground-water withdrawals from the aquifers underlying Kings and Queens Counties varied temporally and spatially during the 20th century and caused extreme changes in water levels. The resultant lowering of water levels during periods of heavy pumping caused saltwater intrusion in nearshore areas and the migration of contaminants from land surface into deep aquifers. The recovery of water levels in response to countywide curtailment of pumping has resulted in the flooding of underground structures. Combined withdrawals for public and industrial supply in Kings and Queens Counties were greatest during the 1930's--about 130 million gallons per day. During this period, a large cone of depression developed in the water table in Kings County; within this depression, water levels were about 45 feet lower than in 1903. All pumping for public supply was halted in Kings County in 1947, and in Jamaica (in Queens County) in 1974. Water levels in Kings County had recovered by 1974 and have remained similar to those of 1903 since then, except for minor localized drawdowns due to industrial-supply or dewatering withdrawals. A large cone of depression that had formed in southeastern Queens County before 1974 has now (1997) disappeared. The estimated combined withdrawal for public supply and industrial supply in Kings and Queens Counties in 1996 was only about 50 million gallons per day. The water-level recoveries in the water-table and confined aquifers generally have resulted in the dilution and dispersion of residual salty and nitrate-contaminated ground water. The majority of recently sampled wells indicate stable or decreasing chloride and nitrate concentrations in all aquifers since 1983. Organic contaminants remain in ground water in Kings, Queens, and Nassau Counties, however; the most commonly detected compounds in 1992-96 were tetrachloroethene, trichloroethene, chloroform, and total trihalomethanes. Water samples from monitoring wells in Kings County indicate a greater number of occurrences of these compounds in the upper glacial aquifer than in the Jameco-Magothy aquifer, whereas samples from public-supply wells in Queens County indicated a greater number of occurrences in the Jameco- Magothy aquifer than in the upper glacial aquifer. This distribution suggests that organic contaminants were not drawn into the deeper aquifers in Kings County before 1947, when their use was limited and deep withdrawals were greatest, and (or) that the longer period of waterlevel recovery in Kings County than in Queens has allowed greater degradation, dilution, and dispersion of any organic contaminants that might have entered the deep aquifers before the cessation of pumping in 1947.

New York↗
USGS2002

Water-table and potentiometric-surface altitudes of the upper glacial, Magothy, and Lloyd aquifers on Long Island, New York, in March-April 2000, with a summary of hydrogeologic conditions

The three main water-bearing units on Long Island, New York--the upper glacial aquifer (water table) and the underlying Magothy and Lloyd aquifers--are the sole source of water supply for more than 3 million people. Water-table and potentiometric-surface altitudes were contoured from water-level measurements made at 394 observation, public-supply, and industrial-supply wells during March-April 2000. In general, water-level altitudes in the upper glacial, Magothy, and Lloyd aquifers were lower throughout most parts of Long Island than those measured during March-April 1997. Changes in altitude during this period ranged from an increase of about 6 feet in the Magothy aquifer in southwestern Nassau County to a decrease of more than 8 feet in the upper glacial aquifer in eastern Suffolk County.

New York↗
USGS1999

Simulation of the effects of development of the ground-water flow system of Long Island, New York

Extensive development on Long Island since the late 19th century and projections of increased urbanization and ground-water use makes effective water-resource management essential for preservation of the island's hydrologic environment and maintenance of a reliable source of water supply. This report presents results of a ground-water flow simulation analysis of the effects of development on the Long Island ground-water system. It describes ground-water levels, stream-flow, and the ground-water budget for the predevelopment period (pre-1900), the 1960's drought, and a more recent (1968-83) period with significant hydrologic stress. The report also presents estimated effects of a proposed water-supply strategy for the year 2020. Long Island has three major aquifers-the upper glacial (water-table), the Magothy, and the Lloyd aquifers-that are separated to varying degrees by confining units. Before development, recharge from precipitation entered the ground-water system at a rate of more than 1.1 billion gallons per day. An equal amount discharged to streams (41 percent), the shore (52 percent), and subsea boundaries (7 percent) . Urbanization and withdrawal of more than 400 Mgal/d (million gallons per day) from wells have resulted in local effects that include declines in ground-water levels, drying up and burial of streams and wetlands, reduction of ground-water recharge by increased overland flow to the ocean, a general decrease in ground-water discharge, and salt water intrusion. In some areas, the reduction in recharge is mitigated by leakage from water-supply and wastewater disposal lines, and infiltration of storm water through recharge basins. During 1968-83, a net loss of 240 Mgal/d from the ground-water system caused a decrease in ground-water discharge to streams (135 Mgal/d), to the shore (82 Mgal/d), and to subsea boundaries (23Mgal/d).The greatest adverse effects have been in western Long Island, where the most severe development has occurred. This analysis shows stream base flow to be highly sensitive to water-table fluctuations, and long streams to be more sensitive than short ones. A water-supply scenario for the year 2020 was simulated that employs redistribution of pumping centers to mitigate extreme local effects . Although the net stress on the ground-water system was projected to increase 57 Mgal/d (24 percent) above that of 1968-83, redistribution of ground-water withdrawals across the island would allow recovery of cones of depression in western Long Island, thereby reducing the threat of salt water intrusion and increasing base flow of some streams . The increased stress would cause a net decrease in base flow island wide of 44 Mgal/d; total base flow would be 281 Mgal/d - 39 percent below predevelopment levels or 14 percent below 1968-83 levels. The most severe effects would be in Nassau and western Suffolk Counties.

New York↗
USGS1999

Simulation of ground-water flow and pumpage in Kings and Queens Counties, Long Island, New York

The potential effects of using ground water as a supplemental source of supply in Kings and Queens Counties were evaluated through a 4-layer finite-difference ground-water-flow model with a uniform grid spacing of 1,333 feet. Hydraulic properties and boundary conditions of an existing regional ground-water-flow model of Long Island with a uniform grid spacing of 4,000 feet were refined for use in the finer grid model of Kings and Queens Counties. The model is calibrated to average pumping stresses that correspond to presumed steady-state conditions of 1983 and 1991. A transient-state simulation of the year-by- year transition between these two conditions was also conducted. Pumping scenarios representing public-supply withdrawals of 100, 150, and 400 million gallons per day (Mgal/d) were simulated to determine the duration of sustainable pumpage, defined as the length of time before a particular pumping rate induces landward hydraulic gradients from areas of salty ground water. The simulations indicate the following hydrologically feasible scenarios: (1) Pumpage of 100 Mgal/d could be sustained for about 10 months, followed by a 46-month period of pumping at reduced (1991) rates, to allow water levels to recover to 90 percent of 1991 levels. (2) Pumpage of 150 Mgal/d could be sustained for about 6 months, followed by a 79-month period of pumping at a reduced (1991) rate. (3) Pumpage of 400 Mgal/d could be sustained for about 3 months from an initial condition of maximum aquifer storage. Each of these scenarios could be modified by injecting surplus water from upstate reservoirs, available from January to May, into the proposed wells. Injection at half the pumpage rate during the recovery period reduces the recovery period to 14 months in scenario 1, 6 months in scenario 2, and 9 months in scenario 3.

New York↗
USGS1999

Pesticides in streams in New Jersey and Long Island, New York, and relation to land use

Pesticide compounds were detected in all 50 water samples collected from streams in New Jersey and Long Island, New York, during June 9-18, 1997. Samples were analyzed for 47 compounds, of which 25 were detected. The number of pesticides detected at each site ranged from 1 to 14. The seven most frequently detected pesticides were atrazine (in 93 percent of samples), metolachlor (86 percent), prometon (84 percent), desethyl-atrazine (78 percent), simazine (78 percent), carbaryl (44 percent), and diazinon (44 percent). All pesticide concentrations were within both U.S. Environmental Protection Agency (USEPA) and State maximum contaminant levels (MCL?s) for drinking water and USEPA lifetime health advisory levels (HAL?s). Concentrations of dieldrin and methylazinphos at one or more sites, however, equaled or exceeded a Federal or State water-quality criterion for aquatic life. The pesticides detected in a stream were related to the land-use composition of the basin. Detection frequencies of 14 of the 25 pesticides detected were highest at agricultural sites; acetochlor, azinphos-methyl, carbofuran, and pebulate were detected only at agricultural sites. Seven compounds were detected most frequently at urban sites; trifluralin, dieldrin, napropamide, and benfluralin were detected only at urban sites. Four compounds were detected most frequently at sites draining areas of mixed land use. No pesticides were detected most frequently at sites draining forested areas. The median concentration and the detection frequency of a given pesticide always were highest in samples from sites in the same land-use category.The median concentrations of seven pesticides at the agricultural sites were at least twice as high as the median concentrations at sites in other land-use categories. The median concentrations of the seven compounds detected most frequently at urban sites were equal to or only slightly higher than the median concentrations at sites in other land-use categories. The median total-pesticide concentration was highest at agricultural sites (0.2 mg/L (micrograms per liter)) and lowest at forested sites (0.025 mg/L). Total-pesticide concentrations varied most at agricultural sites and least at forested sites. Total-pesticide concentration and number of pesticides detected at a site increased as the percentage of agricultural land in the basin increased and decreased as the percentage of undeveloped land increased. Only three of the seven most frequently detected compounds?atrazine, metolachlor, and carbaryl?are among the seven most heavily applied pesticides in New Jersey. This is because detection frequencies are the result of physical and chemical properties of the pesticide compounds as well as application rates. Water solubility and soil-adsorption coefficients appear to be the two physical properties of pesticides that most influence their presence in streams.

New Jersey, New York↗
USGS1999

Relation of pesticide concentrations to season, streamflow, and land use in seven New Jersey streams

The presence and variability of pesticides in seven New Jersey streams was documented by analyzing 146 samples collected from the streams from April 1996 through June 1998. The samples were analyzed for 85 pesticides, including 50 herbicides, 28 insecticides, and 7 degradation products, at method detection limits that ranged from 0.001 to 0.018 &mu;g/L (micrograms per liter). Pesticides were frequently detected; however, concentrations were generally low. The pesticides most frequently detected were atrazine, in 97 percent of the samples; prometon, 96 percent; metolachlor, 95 percent; desethyl-atrazine, 91 percent; simazine, 88 percent; diazinon, 58 percent; alachlor, 56 percent; and carbaryl, 54 percent. Detection frequencies were highest during the growing season (April-September). At least one pesticide was detected in all but one of these samples, and 49 percent of the samples contained 9 or more pesticides. The numbers of pesticides detected at a given site ranged from 13 to 29. Ten pesticides were detected at concentrations that exceeded established water-quality criteria. Thirty-one of these detections were in samples collected during the growing season and one during the nongrowing season. The pesticides that exceeded the U.S. Environmental Protection Agency (USEPA) maximum contaminant level for drinking water were atrazine, which exceeded 3 &mu;g/L in four samples, and alachlor, 2 &mu;g/L in two samples. Cyanazine exceeded the USEPA liftime health advisory level (HAL) of 1 &mu;g/L in two samples. These eight detections occurred during runoff shortly after spring pesticide applications and represent a potential threat to municipal water supplies in the Raritan River basin. Concentrations of chlorpyrifos, chlorthalonil, diazinon, ethyl-parathion, and methyl-azinphos exceeded the chronic life criteria for the protection of aquatic life (ACQR) in 20 samples at four sites during the growing season. Dieldrin was detected in four samples and DDE in two samples at concentrations that exceeded New Jersey Department of Environmental Protection (NJDEP) human health criteria. Individual and total-pesticide concentrations and total numbers of pesticides detected in the samples varied with season and flow conditions. Median and maximum concentrations of most of the pesticides were highest during runoff in the growing season. Pesticide concentrations were typically lower and less variable in the nongrowing season than in the growing season, regardless of changes in hydrologic conditions; however, median concentrations of most pesticides were slightly lower during runoff than during base flow. The median total-pesticide concentration and median total number of pesticides detected were highest and most variable in runoff samples in the growing season. In the nongrowing season, the median total-pesticide concentration was lowest in runoff samples and least variable during base-flow conditions. Median total numbers of pesticides were lowest and least varibale in the nongrowing season during base-flow conditions at most sites. The highest total-pesticide concentrations were detected in samples from the two small agricultural basins (greater than 25 percent of land use is agricultural) during runoff in late spring and early summer. In general, insecticides were detected more frequently and in greater concentrations at urban sites. Concentrations of agricultural herbicides generally decreased with increasing flow at the four sites with less than 10 percent agriculture land use and increased with increasing flow at the three sites with more than 25 percent agricultural land use. Most of the pesticides that correlated positively with streamflow were detected at sites where land use in the basin would indicate the use of those particular pesticides. Most of the pesticides that correlated negatively with streamflow were present at the site in the Coastal Plain or at sites in which the land use in the basin would not indicate heavy u

New Jersey;New York↗
USGS1999

Ground-water resources of Kings and Queens counties, Long Island, New York

From 1981 through 1986, the U.S. Geological Survey investigated the ground-water system of western Long Island, New York, including Kings and Queens counties. This report describes the structure and operation of the western part of the Long Island ground-water system, and the hydrologic effects associated with human development from 1900 to the early 1980's. Recent (early 1980's) ground-water quantity and quality characteristics are described.

New York↗
USGS1997

Spatial variability of volatile organic compounds in streams on Long Island, New York, and in New Jersey

Volatile organic compounds (VOCs) are found in almost all natural and synthetic materials and are commonly used in fuels, fuel additives, solvents, perfumes, flavor additives, and deodorants. Potential health hazards and environmental degradation resulting from the widespread use of VOCs has prompted increasing concern among scientists, industry, and the general public.

New Jersey, New York↗