Acidic Deposition and the Status of Virginia’s Wild Trout Resource:  Revisited

Wild Trout VII, Yellowstone National Park, October 2000

J.R..Webb, F.A..Deviney, Jr., B.J..Cosby, A.J..Bulger, J.N..Galloway

Department of Environmental Sciences
University of Virginia
Charlottesville, Virginia 22903

Quarterly Sampling 1988-1999

Since the initial VTSSS survey in 1987, quarterly sampling (during the last seven days of January, April, July, and October) has been conducted on a geographically and geologically representative subset of native brook trout streams associated with minimally disturbed forested watersheds. With a few exceptions, highly buffered streams associated with carbonate bedrock are not presently included in the quarterly sampling program.

We examined the patterns of estimated trends in sulfate and ANC for 58 streams for which 12 years of quarterly sample data are available. We also examined changes in stream classifications relative to the ANC categories defined by Bulger et al. [2000] for brook trout response to acidification.

Distribution of Trends by Slope Rank Given a binomial test for numbers of positive and negative trends, sulfate results indicated no significant difference. ANC results indicated significantly more negative trends than positive.   Because of ANC trends, some streams were reclassified from transitional or not acidic to chronically or episodically acidic.