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Zimmerman, J. K. H., B. Vondracek, and J. V. Westra. 2003. Environmental Management 32:93 105.
Abstract: We examined the relationship between water quality and fish communities within two agricultural areas using a computer simulation model. Our analyses focused on a cool water stream, Wells Creek in southeastern Minnesota, and a warm water stream, the Chippewa River in western Minnesota. We used the Agricultural Drainage and
Pesticide Transport (ADAPT) model in relation to land use to calculate in-stream suspended sediment concentrations using estimates of sediment delivery, runoff, baseflow and stream bank erosion, and quantified the effects of suspended sediment exposure on fish communities. We predicted the effects of agricultural practices on stream fish communities under several possible land use scenarios,
with reference to current conditions. Land-use changes lead to reductions in sediment loading of up to 84% in Wells Creek and 49% in the Chippewa River. The reduction in sediment loading across scenarios may be directly related to a reduction in runoff by about 35% in both study areas. We found a 98% decrease in "lethal" concentrations of suspended sediment on fish in Wells Creek with
an increase in conservation tillage, riparian buffers, and permanent vegetative cover. However, the effects of suspended sediment did not significantly decrease in the Chippewa River. This difference between study areas was likely due to differential tolerance to suspended sediment between cool water and warm water fish communities and differences in topography, runoff and bank erosion between
the two streams.
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