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Research about Nassau County, New York

Source-linked reports with geographic coverage including Nassau County, New York.

26 records · Page 2Linked to original sources
USGS1976

Factors affecting declining water levels in a sewered area of Nassau County, New York

Double-mass-curve analysis of ground-water levels in Nassau County, Long Island, N.Y., shows that the average-weighted ground-water levels in a 32-mi 2 (83-km 2 ) segment of a sewered area declined 11.8 ft (3.6 m) relative to an adjacent unsewered area to the east during 1953-72. Electric-analog-model analysis indicates that 4.9 ft (1.5 m) of the decline is due to pumping in nearby Queens County, west of the sewered area. Most of the remaining 6.9 ft (2.1 m) of the decline is due to sewering. Streamflow within the sewered area has also declined because of the lowered ground-water levels.

New York↗
USGS1969

Effects of urban development on direct runoff to East Meadow Brook, Nassau County, Long Island, New York

The study described in this report is concerned with the effects of intensive urban development on direct runoff to East Meadow Brook, a southward-flowing stream in central Nassau County, N.Y., during the period 1937-66. The specific objectives of the study were (a) to relate indices of urban development to increases in the volume of annual direct runoff to the stream; (b) to compare hydrograph features at different periods during the transition of the drainage basin from rural to urban conditions; and (c) to compare the rainfall-runoff relations for periods before and after urban development. Periods of housing and street construction in the drainage basin correspond to three distinct periods of increased direct runoff after the base period 1937-43-namely, 1944-51, 1952-59, and 1960-62. During each period, the average annual direct runoff increased because of an increase in the area served by storm sewers that discharged into East Meadow Brook. The amount of land served by sewers increased from about 570 acres in 1943 to about 3,600 acres in 1962, or about 530 percent. During this same period, the average annual direct runoff increased from about 920 acre-feet per year to about 3,400 acre-feet per year, or about 270 percent. The shape of direct-runoff unit hydrographs of East Meadow Brook also changed during the period of study. The average peak discharge of a 1-hour-duration unit hydrograph increased from 313 cubic feet per second, for storms in 1937-43, to 776 cubic feet per second, for storms in 1960-62, or about 2.5 times. In addition, the widths of the unit hydrographs for 1960-62 at values of 50 and 75 percent of the peak discharge were 38 and 28 percent, respectively, the comparable widths of the unit hydrographs for 1937-43. An analysis of the rainfall-runoff relations for both preurban and urban conditions indicates that the direct runoff for both periods increased with the magnitude of the storm. However, the direct runoff during a period of urbanized conditions (1964- 66) was from 1.1 to 4.6 times greater than the corresponding runoff during the preurban period 1937-43, depending on the size of the individual storm. The volume of direct runoff from the parts of the subarea equipped with storm sewers that discharged into East Meadow Brook is estimated to have been roughly 3,000 acre-feet per year in 1960-62, or about 20 percent of the precipitation on those parts of the area. The increase in direct runoff probably represents a loss of ground-water recharge. However, because data changes in evapo-transpiration are insufficient and because the effects of recharge basins are unknown, adequate quantitative estimates of groundwater recharge can not be made. On the basis of the present zoning regulations and on assumption that an additional 320 acres in the Hempstead subarea will be serviced by storm sewers that discharge into East Meadow Brook, direct runoff from the subarea is expected to increase in the future to an estimated 4,000-4,500 acre-feet per year.

New York↗
USGS1960

Position of the salt-water body in the magothy(?) formation in the Cedarhurst-Woodmere area of southwestern Nassau county, Long Island, N.Y.

The position and chloride concentration of a sizable body of salt water , moving slowly landsyard from the south-shore bays of Long Island and the Atlantic Ocean were defined by recent test drilling in the Cedarhurst-Woodmere area of southwestern Nassau County, Long Island, N. Most of the salt-water body is in the lower part of a permeable artesian aquifer; the lowermost part of the salt-water body is in clay deposits underlying the permeable aquifer. The upper limit of the salt-water body in this area was found at depths increasing progressively in a landward direction. It was 318 feet below sea level at a well in Cedarhurst and 541 feet below sea level at a well in Woodmere. The lower limit of the salt-water body was determined at depths between 578 and 630 feet below sea level in the Cedarhurst-Woodmere area. The salt-water body is more than 300 feet thick at a well in Cedarhurst, and it thins out to zero in the vicinity of a pumping center about 1- miles northeast of the Cedarhurst well. Chloride concentration in the salt-water body in the Cedarhurst-Woodmere area ranged from about 40 to 16,000 ppm (parts per million). Isochlors define a zone of diffusion about a mile wide in the Cedarhurst-Woodmere area. They indicate a thickness of diffused water ranging from a few tens to more than 150 feet vertically. Electrical-log data show that the upper boundary of the salt-water body moved upward 21 feet between 1952 and 1958 at a site in Woodmere about half a mile southwest of the pumping center. ' From this information it is inferred that between 1952 and 1958 the leading edge of the saltwater front moved landward about 2,000 feet toward the pumping center.

New York↗
USGS1959

Ground-water levels and related hydrologic data from selected observation wells in Nassau County, Long Island, New York

Nassau County has experienced a rapid growth in population and industry in the past 20 years that has resulted in increased development of its ground-water resources. The county is located in west-central Long Island and its boundaries enclose a land area of 274 square miles. The climate is relatively mild and precipitation averages 43 inches a year. The precipitation is the ultimate source of natural replenishment to the ground-water reservoir. Ground water is found in the pore spaces of unconsolidated sands, gravels, and clays which overlay a basement of crystalline bedrock.

New York↗
USGS1951

Pumping test at Levittown, Nassau County, New York, September 16-18, 1949

This report presents and discusses the quantitative and qualitative data obtained during a pumping test at the Levittown housing development in Nassau County, N. Y. One of the ten principal supply wells, screened in the sands of the Magothy (?) formation which is overlain unconformably by the sand and gravel of the upper Pleistocene deposits, was pumped for more than 24 hours at a rate of 790 gallons per minute. During this time the develop ment of the cone of depression extended a distance of more than 1,000 feet from the pumping well. A coefficient of transmissibility of 245,0W gallons per day per foot was computed and a coefficient of storage of 0.13 was de termined at the site of the pumping test. The qualitative results show that the two aquifers at the pumping-test site, that is, the sand and gravel of the upper Pleistocene deposits and the underlying sands of the Magothy (?) formation, function essentially as one hydrologic unit. Such information, together with other data of this kind, assumes importance when it is realized that the New York rater Power and Control Commission by regulation considers every aquifer as a separate and distinct hydrologic unit. It thus requires the return of water pumped for cooling and other similar uses to the same aquifer from which the water taken, unless sufficient evidence is obtained to show that two adjacent aquifers function as a single hydrologic unit. Sufficient data were obtained during the test to suggest that perhaps about 14 feet of the 19.7 feet measured as drawdown in the pumped well is attributable to well and screen losses.

New York↗
USGS1950

Salinity of ground water at sampling wells located in southeastern Nassau County, Long Island, New York

In 1939, a special program for the systematic collection of chloride data in southeastern Nassau County was inaugurated in which three agencies participated. The Nassau County Department of Public Works constructed the sampling wells, the Ground Water Branch of the U.S. Geological Survey began to collect at period intervals water samples which were analysed at the Mount Prospect Laboratory of the New York Department of Water Supply, Gas and Electricity, The Nassau County Department of Public Works and the U.S. Geological Survey have continued financial cooperation for the maintenance of this program up to the present time.

New York↗