Targeting the ebb at Mountain Lake

Jessica Coker, interim director of the Mountain Lake Conservancy, looks off the boat ramp toward the lake in Giles County. Mountain Lake is one of only two natural lakes in Virginia and has been at "low pond" since 2008. Matt Gentry| The Roanoke Times

Stone cairns mark the shore level of Mountain Lake which has been at "low pond" since 2008. Matt Gentry | The Roanoke Times

Researchers have released a small amount of dye in Mountain Lake to study its wavering water level, which falls as water drains out holes in the lake floor.

Never before has dye research such as the current study been used to understand the lake’s odd behavior. But it could be several weeks or months before results of the experiment are released.

In a spectacle that’s both awesome and irksome, the rare natural lake in Giles County sporadically shrinks to little more than a couple of wide but deep mud puddles. In time, springs partially replenish the lake, which can span 50 acres when full and sits adjacent to a resort hotel.

Located near Pembroke, it is one of two natural lakes in Virginia and is kept open for year‑round visitation by the Mountain Lake Conservancy, a nonprofit organization founded to help manage and protect the 2,600 acres of Mountain Lake property and foster environmental and cultural education — the edict of its late owner, Mary Moody Northen.

In the launch of the latest experiment, researchers including Virginia Tech Geological Sciences master’s student Luke Joyce, along with engineering geologists Skip Watts and George Stephenson from Radford University, put the green tracer dye into the lake in mid-January. They applied a pound above each of four drain holes, boring through ice to access the water.

They also set up charcoal-based detectors to trap the dye if it shows up in streams of the surrounding watersheds.

Jessica Coker, interim director of the conservancy, said the color that the dye appears ranges from green to orange to red to invisible depending on the dilution and background.

A laboratory will read the traps once they are removed from streams. No results have been released.
Researchers have established that lake water escapes through the lake bottom.

“It’s very much like a bathtub,” Watts said. “There are pretty good-sized holes at the deep end.”

The dye is supposed to help determine where the water goes after leaking out.
Buzz Scanland, who manages the hotel, said the periodic near-depletion of the lake hurts business.

“I think what we’ve got to do is seal up some of those points where the water is going out,” he said.

Coker said some view the water drop, and the exposure of lake bottom, as disruptive to lake ecology as well. Right now, the lake, while rising, is 59 feet below full pond and holding about 6 percent of its potential total water volume, Coker said.

But even if research offers a possible strategy to modify the lake, some people may not want the “unique process” by which the lake rises and falls disturbed, Coker said.

Any changes would be up to the board of directors of the Texas-based Mary Moody Northen Endowment, which owns the property, she said.
Mountain Lake Hotel, its dining room and gift shop plan to stage a seasonal opening celebration in early May.

The BrewRidge Music Festival is scheduled from noon to 5 p.m. on May 5.
The hotel will then be open seven days a week through October.

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