Trends in Nitrogen Concentration and Nitrogen Loads Entering the ...
Prepared in cooperation with New York State Department of State
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
Water-Resources Investigations Report 02-4255 U.S. Department of the Interior U.S. Geological Survey
Cover photograph: Narrow stretch of water in the South Shore Estuary Reserve where you can see across to the other side. The photo was taken from Smith Point Marina just west of Smith Point bridge. (Photograph by Jack Monti, Jr.; USGS)
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 By Jack Monti, Jr. and Michael P. Scorca
U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 02-4255
Prepared in cooperation with NEW YORK STATE DEPARTMENT OF STATE
Coram, New York 2003
i
U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary U.S. Geological Survey Charles G. Groat, Director
The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. ______________________________________________________________________ For additional information write to:
Copies of this report may be purchased from:
U.S. Geological Survey 2045 Route 112, Bldg. 4 Coram, NY 11727
U.S. Geological Survey Branch of Information Services Box 25286, Bldg. 810 Denver, CO 80225-0286
ii
CONTENTS Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Purpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Previous studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Physiography and hydrogeology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground-water system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effects of urbanization on streamflow and ground water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Historic changes in base flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effects of sanitary sewers, storm sewers, and recharge basins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Method and approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stream data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discharge data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen-concentration data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Estimation of annual stream loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground-water data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discharge data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen-concentration data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Estimation of ground-water loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Factors affecting load calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen concentrations in streams and ground water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Geographic trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nassau County. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Suffolk County. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Seasonal trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Long-term trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Geographic trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Temporal trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trends with depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen loads entering the South Shore Estuary Reserve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Annual stream loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Geographic trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Temporal trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground-water loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Shallow-ground-water system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Deep-ground-water system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Total nitrogen load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 2 3 4 4 4 8 8 8 9 9 9 10 10 11 11 12 12 13 15 15 16 16 17 17 18 18 18 21 21 21 26 26 27 27 27 27 32 32 32 33 34
FIGURES 1. Map showing location of study area and South Shore Estuary Reserve, Long Island, N.Y. . . . . . . . . . . . . . . . . . . . . . 2. Map showing locations of 13 selected streams that discharge to the South Shore Estuary Reserve from Nassau and Suffolk Counties, N.Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contents
3 5
iii
3. Generalized section showing hydrogeologic units and generalized directions of ground-water flow on the north and south shores of Long Island, N.Y. (Modified from Nemickas and others, 1989, fig. 8). . . . . . . . . . . . . . . . . . . . 4. Map showing partial model grid and locations of upper layer (layer 1) constant-head cells representing the South Shore Estuary Reserve in the U.S. Geological Survey Long Island regional ground-water flow model . . . . . . . . . . 5. Vertical section showing model hydrogeologic geometry along column 50, constant-head cells in layer 1, and simulated shallow- and deep-ground-water discharge entering the South Shore Estuary Reserve (SSER) . . . . . . . . 6. Map showing locations of 192 wells on the south shore of Nassau and Suffolk Counties, N.Y. for which at least one sample was available with a calculated total nitrogen value during 1952-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Map showing location of the 1-mile-wide zone along the south shore of Nassau and Suffolk Counties, N.Y., and the five geographic areas into which it was divided for comparison of geographic trends in total nitrogen and nitrate concentrations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. Boxplots showing distribution of total nitrogen concentration in 13 selected streams on the south shore of Nassau and Suffolk Counties, N. Y., 1971-97.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9. Boxplots showing distribution of nitrogen concentration for summer (April through September) and winter (October through March) during 1971-97 at 13 south shore streams in Nassau and Suffolk Counties, N.Y. . . . . . . 10. Graphs showing total nitrogen concentrations of 13 selected streams on the south shore of Nassau and Suffolk Counties, N.Y., 1971-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. Boxplots showing distribution of nitrogen concentration in streams on the south shore of Nassau and Suffolk Counties, N.Y. during selected time periods: A. In the nine streams in sewered areas. B. In the four streams in unsewered areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12. Boxplots showing distribution of total nitrogen concentrations in samples from streams and shallow wells, and nitrate concentrations in samples from deep wells in the five geographic areas within 1 mile of the south shore of Nassau and Suffolk Counties, N.Y., 1952-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13. Boxplots showing distribution of nitrogen concentrations in samples from shallow wells in Areas A through E along south shore of Nassau and Suffolk Counties, N. Y., for four selected time periods . . . . . . . . . . . . . . . . . . . . . 14. Graphs showing annual mean discharge, mean nitrogen concentration, and mean nitrogen load calculated for 11 selected south-shore streams that discharge to the South Shore Estuary Reserve from Nassau and Suffolk Counties, N.Y., 1972-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15. Boxplots showing distribution of nitrogen load calculated in 11 selected streams on the south shore of Nassau and Suffolk Counties, N.Y. 1972-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16. Bar chart showing combined nitrogen load from four streams in Nassau County and seven in Suffolk County, N.Y. that discharge to the South Shore Estuary Reserve during 1972-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6 13 14 15
16 17 19 20
22
24 25
29 31 32
Tables 1. Generalized description of principal hydrogeologic units underlying Long Island, N.Y. . . . . . . . . . . . . . . . . . . . . . . 7 2. Drainage area, period of record, mean discharge, and water-sampling data for the 13 selected streams that discharge to the South Shore Estuary Reserve, Long Island, N.Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3. Maximum, median, and minimum total nitrogen concentrations for the 13 selected streams that discharge to the South Shore Estuary Reserve from Nassau and Suffolk Counties, N.Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4. Simulated annual mean discharge from shallow and deep ground water to South Shore Estuary Reserve, Nassau and Suffolk Counties, N.Y., based on 1983 steady-state hydrologic conditions . . . . . . . . . . . . . . . 13 5. Time periods used in temporal-trend analysis of nitrogen concentrations in streams of Nassau and Suffolk Counties, N.Y., 1952-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 6. Number of samples collected from selected shallow and deep wells within 1 mile of the south shore of Nassau and Suffolk Counties, N.Y., and maximum, median, and minimum concentrations of nitrogen at shallow wells and of nitrate at deep wells, 1952-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 7. Minimum, maximum, and median total nitrogen concentrations in shallow and deep ground water in Areas A through E of South Shore Estuary Reserve, Nassau and Suffolk Counties, N.Y., 1952-97. . . . . . . . . . . . . . . . . . . . . 23 8. Geographic grouping of the 13 selected streams that discharge to the South Shore Estuary Reserve, Long Island, N.Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 9. Estimated annual nitrogen loads entering the South Shore Estuary Reserve from 11 streams on the south shore of Long Island, N.Y., 1972-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
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Contents
10. Median concentration and annual load of nitrogen entering the South Shore Estuary Reserve from shallow and deep ground water in Nassau and Suffolk Counties, N.Y., as calculated from concentrations at wells within 1 mile of the shore, 1952-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. Total annual nitrogen load entering the South Shore Estuary Reserve from streams and ground water on the south shore of Long Island, N.Y., 1972-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31 33
CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS Multiply
foot (ft) mile (mi)
acre square mile (mi2)
foot per day (ft/d) cubic foot per second (ft3/s)
ton
By
To Obtain
Length 0.3048 1.609
meter (m) kilometer (km)
Area 4,047 2.59 Flow 0.3048 0.02832 Mass 907.2
square meter (m2) square kilometer (km2)
meter per day (m/d) cubic meter per second (m3/s)
kilogram (kg)
Chemical Concentration milligrams per liter (mg/L) Other Abbreviations Used nitrogen (N) kilograms per year (kg/yr) million gallons per year (Mgal/yr) cubic meters per year (m3/yr) year (yr) second (s) less than (
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
Water-Resources Investigations Report 02-4255 U.S. Department of the Interior U.S. Geological Survey
Cover photograph: Narrow stretch of water in the South Shore Estuary Reserve where you can see across to the other side. The photo was taken from Smith Point Marina just west of Smith Point bridge. (Photograph by Jack Monti, Jr.; USGS)
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 By Jack Monti, Jr. and Michael P. Scorca
U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 02-4255
Prepared in cooperation with NEW YORK STATE DEPARTMENT OF STATE
Coram, New York 2003
i
U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary U.S. Geological Survey Charles G. Groat, Director
The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. ______________________________________________________________________ For additional information write to:
Copies of this report may be purchased from:
U.S. Geological Survey 2045 Route 112, Bldg. 4 Coram, NY 11727
U.S. Geological Survey Branch of Information Services Box 25286, Bldg. 810 Denver, CO 80225-0286
ii
CONTENTS Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Purpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Previous studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Physiography and hydrogeology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground-water system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effects of urbanization on streamflow and ground water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Historic changes in base flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effects of sanitary sewers, storm sewers, and recharge basins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Method and approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stream data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discharge data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen-concentration data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Estimation of annual stream loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground-water data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discharge data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen-concentration data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Estimation of ground-water loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Factors affecting load calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen concentrations in streams and ground water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Geographic trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nassau County. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Suffolk County. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Seasonal trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Long-term trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Geographic trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Temporal trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trends with depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen loads entering the South Shore Estuary Reserve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Annual stream loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Geographic trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Temporal trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground-water loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Shallow-ground-water system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Deep-ground-water system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Total nitrogen load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 2 3 4 4 4 8 8 8 9 9 9 10 10 11 11 12 12 13 15 15 16 16 17 17 18 18 18 21 21 21 26 26 27 27 27 27 32 32 32 33 34
FIGURES 1. Map showing location of study area and South Shore Estuary Reserve, Long Island, N.Y. . . . . . . . . . . . . . . . . . . . . . 2. Map showing locations of 13 selected streams that discharge to the South Shore Estuary Reserve from Nassau and Suffolk Counties, N.Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contents
3 5
iii
3. Generalized section showing hydrogeologic units and generalized directions of ground-water flow on the north and south shores of Long Island, N.Y. (Modified from Nemickas and others, 1989, fig. 8). . . . . . . . . . . . . . . . . . . . 4. Map showing partial model grid and locations of upper layer (layer 1) constant-head cells representing the South Shore Estuary Reserve in the U.S. Geological Survey Long Island regional ground-water flow model . . . . . . . . . . 5. Vertical section showing model hydrogeologic geometry along column 50, constant-head cells in layer 1, and simulated shallow- and deep-ground-water discharge entering the South Shore Estuary Reserve (SSER) . . . . . . . . 6. Map showing locations of 192 wells on the south shore of Nassau and Suffolk Counties, N.Y. for which at least one sample was available with a calculated total nitrogen value during 1952-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Map showing location of the 1-mile-wide zone along the south shore of Nassau and Suffolk Counties, N.Y., and the five geographic areas into which it was divided for comparison of geographic trends in total nitrogen and nitrate concentrations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. Boxplots showing distribution of total nitrogen concentration in 13 selected streams on the south shore of Nassau and Suffolk Counties, N. Y., 1971-97.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9. Boxplots showing distribution of nitrogen concentration for summer (April through September) and winter (October through March) during 1971-97 at 13 south shore streams in Nassau and Suffolk Counties, N.Y. . . . . . . 10. Graphs showing total nitrogen concentrations of 13 selected streams on the south shore of Nassau and Suffolk Counties, N.Y., 1971-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. Boxplots showing distribution of nitrogen concentration in streams on the south shore of Nassau and Suffolk Counties, N.Y. during selected time periods: A. In the nine streams in sewered areas. B. In the four streams in unsewered areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12. Boxplots showing distribution of total nitrogen concentrations in samples from streams and shallow wells, and nitrate concentrations in samples from deep wells in the five geographic areas within 1 mile of the south shore of Nassau and Suffolk Counties, N.Y., 1952-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13. Boxplots showing distribution of nitrogen concentrations in samples from shallow wells in Areas A through E along south shore of Nassau and Suffolk Counties, N. Y., for four selected time periods . . . . . . . . . . . . . . . . . . . . . 14. Graphs showing annual mean discharge, mean nitrogen concentration, and mean nitrogen load calculated for 11 selected south-shore streams that discharge to the South Shore Estuary Reserve from Nassau and Suffolk Counties, N.Y., 1972-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15. Boxplots showing distribution of nitrogen load calculated in 11 selected streams on the south shore of Nassau and Suffolk Counties, N.Y. 1972-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16. Bar chart showing combined nitrogen load from four streams in Nassau County and seven in Suffolk County, N.Y. that discharge to the South Shore Estuary Reserve during 1972-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6 13 14 15
16 17 19 20
22
24 25
29 31 32
Tables 1. Generalized description of principal hydrogeologic units underlying Long Island, N.Y. . . . . . . . . . . . . . . . . . . . . . . 7 2. Drainage area, period of record, mean discharge, and water-sampling data for the 13 selected streams that discharge to the South Shore Estuary Reserve, Long Island, N.Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3. Maximum, median, and minimum total nitrogen concentrations for the 13 selected streams that discharge to the South Shore Estuary Reserve from Nassau and Suffolk Counties, N.Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4. Simulated annual mean discharge from shallow and deep ground water to South Shore Estuary Reserve, Nassau and Suffolk Counties, N.Y., based on 1983 steady-state hydrologic conditions . . . . . . . . . . . . . . . 13 5. Time periods used in temporal-trend analysis of nitrogen concentrations in streams of Nassau and Suffolk Counties, N.Y., 1952-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 6. Number of samples collected from selected shallow and deep wells within 1 mile of the south shore of Nassau and Suffolk Counties, N.Y., and maximum, median, and minimum concentrations of nitrogen at shallow wells and of nitrate at deep wells, 1952-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 7. Minimum, maximum, and median total nitrogen concentrations in shallow and deep ground water in Areas A through E of South Shore Estuary Reserve, Nassau and Suffolk Counties, N.Y., 1952-97. . . . . . . . . . . . . . . . . . . . . 23 8. Geographic grouping of the 13 selected streams that discharge to the South Shore Estuary Reserve, Long Island, N.Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 9. Estimated annual nitrogen loads entering the South Shore Estuary Reserve from 11 streams on the south shore of Long Island, N.Y., 1972-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
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10. Median concentration and annual load of nitrogen entering the South Shore Estuary Reserve from shallow and deep ground water in Nassau and Suffolk Counties, N.Y., as calculated from concentrations at wells within 1 mile of the shore, 1952-97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. Total annual nitrogen load entering the South Shore Estuary Reserve from streams and ground water on the south shore of Long Island, N.Y., 1972-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31 33
CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS Multiply
foot (ft) mile (mi)
acre square mile (mi2)
foot per day (ft/d) cubic foot per second (ft3/s)
ton
By
To Obtain
Length 0.3048 1.609
meter (m) kilometer (km)
Area 4,047 2.59 Flow 0.3048 0.02832 Mass 907.2
square meter (m2) square kilometer (km2)
meter per day (m/d) cubic meter per second (m3/s)
kilogram (kg)
Chemical Concentration milligrams per liter (mg/L) Other Abbreviations Used nitrogen (N) kilograms per year (kg/yr) million gallons per year (Mgal/yr) cubic meters per year (m3/yr) year (yr) second (s) less than (
