Virginia's wild trout streams are much more sensitive to acid pollution than previously thought, and its southwestern mountain forests are showing signs of "severe damage," according to the results of two recent independent studies.

Scientists at the University of Virginia tested 353 wild trout streams and found that half were "extremely sensitive" to acid, and 11 percent had already "acidified," said Dr. James Galloway, associate professor of environmental science.

"If you're a fisherman, and interested in going to the mountains and catching trout in your favorite fish stream, these results indicate that sometime in the future, you may not be able to do it," Galloway said.

Meanwhile, scientists at the University of New Hampshire, studying satellite images, have discovered that Virginia's red spruce and fraser fir trees, including those at Mount Rogers, the state's highest peak at elevation 5,729 feet, appear to be under considerable stress.

Scientists cannot say with certainty how many trees are dead or dying, or what is causing the damage, or how fast it is occurring. Using remote satellite images to assess forest health is a new technique, and they want to verify their findings against data obtained on the ground before commenting, said U-N.H. Associate Professor Barry Rock.

The studies could prove helpful in forming a Virginia policy for dealing with suspected pollutants, including nitric and sulfuric acids, which state officials believe are drifting here from heavily industrialized sections of the Midwest.

The research will also be used as base line data, with which to chart future changes in stream or forest conditions. There is no such comprehensive historical data for Virginia's resources.

The trout stream study is part of a two-year, $88,500 state-federal effort. It is being conducted by U-Va. scientists, with help from hundreds of volunteers, for the Virginia Department of Game and Inland Fisheries.

An estimated 80 percent of Virginia's wild mountain trout streams were tested. All are in western counties, including Rappahannock, Warren and Shenandoah, scientists said.

The 20 percent of trout streams not tested are those whose stream chemistries have been affected by nearby development, or those whose surrounding soils contain high levels of calcium carbonate, an acid buffer.

Scientists had guessed that perhaps one-third of streams tested might be sensitive to acidification, based on 1980 studies of 55 Shenandoah National Park streams. "But," Galloway said, "we were wrong."

He could not comment on acid levels of individual streams; those findings have not yet been released.

But he called the acid-sensitivity findings significant; just as coal miners used canaries to warn them when the air in the mines was going bad, trout streams, because of their keen environmental susceptibility, can act for scientists as modern canaries.

Said Dan Salkovitz, staff meteorologist for the State Air Pollution Control Board, of the trout stream study: "What they've done is take a snapshot of what the streams' state is right now, and the key is going to be for them to go back in the second phase of the study and determine what is actually happening."

The study will continue with the testing every three months of 65 trout streams.

The forest study is part of a $140,000 satellite imaging pilot program being done by U-N.H. scientists for the U.S. Forest Service, Rock said. Work began a year ago, and has included study of other forests, including Whiteface Mountain in New York, and Mount Mitchell in North Carolina.

Using satellite images, scientists are able to infer by comparing red to blue or green splotches that forest damage has apparently occurred at both Mount Rogers and at White Top Mountain, near Damascus, Va. Scientists will not know for certain until their findings are checked against ground observations, although one visit to Mount Rogers already has revealed evidence of yellowing leaves and defoliated trees, Rock said.

"Again, we can't say what the cause is," Rock said, adding that the problem could be insects, winter damage, pollutants -- "a number of things." Most of the damage appears to be at high elevations, on northwest-facing slopes.

Previous studies have shown that Virginia's rainfall is at least 10 times as acidic as might be expected in remote areas of the world, but comparable to precipitation in other developed parts of the United States, Galloway said.

Rain samples taken from eight stations around the state, including Fairfax County, show that Virginia's rain has an average relative acidity of pH 4.3 on a scale of acidity to alkalinity that runs from 0 to 14, with 7 being neutral and 0 extremely acid. The pH of normal rain is considered to be somewhere between 5.0 and 5.6, although there is considerable debate, according to the state Air Pollution Control Board.

One of Virginia's best-known acid rain studies involves Deep Run, a Shenandoah National Park stream. Acid levels there have increased over seven years, from pH 5.8 to 5.4, and scientists have said that this change may be attributable to the release of accumulated sulfates from surrounding soil.

Having first fallen to the ground as air pollution, the sulfates became concentrated in the ground. When the ground could no longer absorb them, sulfates began to leach into the water, causing a change in the pH level, Galloway said.