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Water quality of Corydon Reservoir before implementation of agricultural best-management practices in the basin, Wayne County, Iowa, September 1990 to September 1991

Water-Resources Investigations Report 93-4099

Prepared in cooperation with Iowa Department of Natural Resources (Geological Survey Bureau), U.S. Environmental Protection Agency, U.S. Department of Agriculture
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Abstract

A hydrologic investigation to define the water quality of Corydon Reservoir before implementation of agricultural best-management practices in the basin was conducted from September 1990 to September 1991. Runoff from the 1,680-acre basin is the primary source of water to the 58-acre reservoir. Current water quality of the reservoir is affected substantially by runoff from the agricultural basin. Total-solids, total-nitrogen, and total-phosphorus concentrations were largest during April through July 1991, the months of greatest rainfall. Herbicide concentrations increased substantially in June after application. The concentration of the sum of all triazines was greater than 50 micrograms per liter in one sample, with the predominant herbicides being atrazine and cyanazine. Atrazine concentrations, estimated from immunoassay, were greater than 8.0 micrograms per liter from June through September 1991 as a result of reservoir storage. Atrazine concentrations commonly were less at the surface than at depth. Algal populations remained constant even though nutrient concen- trations increased during the summer months. This may be due to the presence of suspended sediment that reduces light penetration and herbicides that inhibit photosynthesis.

Study Area

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Water quality of Corydon Reservoir before implementation of agricultural best-management practices in the basin, Wayne County, Iowa, September 1990 to September 1991
Series title:
Water-Resources Investigations Report
Series number:
93-4099
Year Published:
1993
Language:
Enlish
Publisher:
U.S. Geological Survey
Publisher location:
Iowa City, IA
Contributing office(s):
Iowa Water Science Center
Description:
vi, 36 p.: ill., maps; 28 cm.
Country:
United States
State:
Iowa
County:
Wayne County
Other Geospatial:
Corydon Reservoir basin
Online Only (Y/N):
N
Additional Online Files (Y/N):
N