Current, reconstructed past, and projected future status of brook trout (Salvelinus fontinalis) streams in Virginia

Southern Appalachian streams host a rich diversity of fishes, but the South ern Appalachian Assessment concluded that 70% of stream locations showed si gnificant fish community degradation, partly due to acid deposition. About 40% of total Southern Appalachian trout stream length occurs in Virginia. O ur research in Shenandoah National Park, Virginia, has documented both chro nic and episodic acidification in streams and brook trout (Salvelinus fonti nalis) mortality during acid episodes. Here, we analyze a representative sa mple of 60 Virginia brook trout streams on noncarbonate bedrock with minima l human disturbance in their watersheds. Of more than 300 such streams in V irginia, only about 50% are currently suitable for brook trout, based on th eir acidification status. For the population of brook trout streams to whic h this analysis applies, model-based projections indicate that continued su lfate deposition at 1991 levels will result in about 70 additional streams becoming chronically acidic and unsuitable for brook trout. A 40% reduction will result in about 48 additional chronically acidic streams. Even a 70% reduction will likely result in about 15 additional streams becoming acidif ied. We conclude that reductions in sulfate deposition greater than 70% (re lative to 1991 levels) are needed to prevent more brook trout stream losses in Virginia.