Effect of the Cedar River on the quality of the ground-water supply for Cedar Rapids, Iowa

Water-Resources Investigations Report 94-4211




Surface Water Treatment Rule under the Safe Drinking Water Act, 1986 requires that public water supplies be evaluated for susceptibility to surface water effects. The aquifer adjacent to the Cedar River in east-central Iowa is evaluated for biogenic material and monitored for selected water-quality properties and constituents to determine the effect of surface-water on the water supply for the City of Cedar Rapids, Iowa. Results from monitoring of selected water-quality effects. Estimated traveltimes from the river to the municipal well ranged from 7 to 17 days. This would indicate that the ground water has a short residence time in the aquifer before it is pumped out for consumption. Above-normal stream-flow and precipitation during the study could have increased the effect the river had on the alluvial aquifer and the possibility of contamination by a pathogen. Microscopic particulate analysis of 29 samples found on Giardia cysts or Crytosporidium oocysts in water collected from municipal wells. Biological values for selected municipal wells tested indicate that the aquifer is filtering out large numbers of algae, diatoms, rotifers, and nematodes as well as filtering out Cryptosporidium, Giardia and other protozoa. A relative risk factor was determined for the aquifer. One municipal well had a high-risk factor, three other wells had a moderate-risk factor, and four wells had a low-risk factor. Data also indicate at least a 99.9 percent reduction in particulates between the river and the wells.

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USGS Numbered Series
Effect of the Cedar River on the quality of the ground-water supply for Cedar Rapids, Iowa
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Water-Resources Investigations Report
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U.S. Geological Survey ; U.S.G.S. Earth Science Information Center, Open-File Reports Section [distributor],
vi, 68 p. :ill., maps ;28 cm.