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A reconnaissance study of saltwater contamination in the El Dorado aquifer, Union County, Arkansas

Water-Resources Investigations Report 84-4012

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Abstract

Since 1960 chloride concentrations in the El Dorado aquifer have increased near El Dorado, Arkansas. The aquifer is a major source for municipal and industrial water supply in Union County. Greatest withdrawal occurs near El Dorado. Because of this withdrawal, the potentiometric surface at El Dorado has been lowered more than 300 feet. Geologic, hydrologic, and chemical data indicate that water from a graben south and east of El Dorado is the source of contamination from salt within the El Dorado aquifer. The data indicates that surface brines and deeper aquifers are not the sources of chloride contamination. Lowering the potentiometric surface near El Dorado has caused water to move out of the graben toward El Dorado. Estimates based on interpretation of electric logs for two wells in the graben indicate chloride equivalents may be as high as 2,500 milligrams per liter in the aquifer. Concentrations outside the graben range from 130 to 650 milligrams per liter at the west end of the graben and from 25 to 150 milligrams per liter farther west and north. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
A reconnaissance study of saltwater contamination in the El Dorado aquifer, Union County, Arkansas
Series title:
Water-Resources Investigations Report
Series number:
84-4012
Edition:
-
Year Published:
1984
Language:
ENGLISH
Publisher:
U.S. Geological Survey, Water Resources Division,
Description:
v, 47 p. :ill., maps (some folded) ;28 cm.