SNY MAGILL WATERSHED MONITORING PROJECT: BASELINE DATA
Iowa Department of Natural Resources, Geological Survey Bureau,
Technical Information Series 32, 1994, p. 43-62

SUMMARY OF BASELINE WATER-QUALITY DATA FOR SNY MAGILL AND BLOODY RUN WATERSHEDS, AND SURROUNDING LOCATIONS

L.S. Seigley(1) and G.R. Hallberg(2)

(1)Iowa Department of Natural Resources, Geological Survey Bureau
109 Trowbridge Hall
Iowa City, IA 52242-1319

(2)University of Iowa Hygienic Laboratory
University of Iowa; Oakdale Campus
Iowa City, IA 52242

ABSTRACT


Historic water quality data was compiled for Sny Magill and Bloody Run creeks, for surrounding creeks and rivers, and for groundwater from the Big Spring basin to give perspective on past quality of surface water and groundwater in the northeastern Iowa area. The water-quality data illustrates an increase in nitrate concentrations with increases in agricultural landuse and management changes. Average nitrate-N concentrations from Sny Magill and Bloody Run have approximately doubled from 1976-78 to 1991. The studies illustrate both temporal and seasonal changes in water quality. The coldwater streams in the region generally have good water quality, especially during groundwater dominated baseflow periods. Data from across the region showed typical downstream declines in nitrate concentrations, related to in-stream nutrient consumption and denitrification. The historic water-quality data, especially from the Big Spring basin, illustrates the need for long-term monitoring to document improvements in water quality from land management changes and to account for extreme climatic conditions.