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Effects of residential and agricultural land uses on the chemical quality of baseflow of small streams in the Croton Watershed, southeastern New York

Water-Resources Investigations Report 99-4173

Prepared in cooperation with the New York City Department of Environmental Protection
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Abstract

Data on the chemical quality of baseflow from 33 small streams that drain basins of differing land-use type and intensity within the Croton watershed were collected seasonally for 1 year to identify and characterize the quality of ground-water contributions to surface water. The watershed includes twelve of New York City's water-supply reservoirs. Baseflow samples were collected a minimum of three days after the most recent precipitation and were analyzed for major ions, boron, and nutrients.

Findings—

  • Concentrations of selected chemical constituents in baseflow were strongly affected by the predominant land use in a given basin. Land uses included forested undeveloped, unsewered residential, sewered residential, and agricultural (horse and dairy farms).
  • A positive linear relation was indicated for chloride concentration in baseflow and the basin's annual rate of road-salt application (or density of two-lane roads). Chloride concentration exhibits a relatively stable relation to road-salt application rate or 2-lane road density throughout the year.
  • Positive linear relations were indicated for nitrate concentration in baseflow and the basins unsewered housing density. Nitrate is characterized by a different relation to unsewered housing density for each season, with the highest observed nitrate concentrations during the winter and the lowest concentrations during the summer.
  • Baseflow nitrate concentrations in sewered basins, and in unsewered basins with riparian wetland buffers between residential development and the stream, were lower than concentrations predicted from unsewered-housing density.

Study Area

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Effects of residential and agricultural land uses on the chemical quality of baseflow of small streams in the Croton Watershed, southeastern New York
Series title:
Water-Resources Investigations Report
Series number:
99-4173
Year Published:
2000
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Description:
15 p.
Country:
United States
State:
Connecticut, New York
Other Geospatial:
Croton Watershed
Online Only (Y/N):
N
Additional Online Files (Y/N):
N