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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

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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.

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
Edition:
-
Year Published:
2000
Language:
ENGLISH
Publisher:
Dept. of the Interior, U.S. Geological Survey ;Branch of Information Services, distributor,
Description:
15 p. :col. ill., col. map ;28 cm.