| Research: Mountain Lake
Recent years have revealed a pattern in the water level of Mountain Lake that was presumed to be a new phenomenon of water "draining" from this basin. Further study by our researchers has uncovered what has proven to be an ancient pattern of cycles that leave the water level of Mountain Lake both "up" and "down" for extended periods of time. The reason has to do with how much water Mother Nature gives us in the form of rainfall.
Water Level
What keeps the lake "full" is the amount of water that flows into the lake from groundwater, e.g. rain & melted snow. dry years equals less input; wet years equals more input.
When we have a "dry" season, less water flows into the lake while water is still flowing out, causing the lake to look like we've pulled the plug! All year long, the lake's water level fluctuates according to the amount of rainfall we've had up here.
So, whether there's a "full pond" or "low pond", this basin on top of salt pond mountain is naturally wet and dry.
Either way, be sure to enjoy a swim in the freshest water around! (a balmy 69 deg F -19 deg C in summer, a cool 45 deg F -7 deg C in the winter!)
Here's how it works:
The basin upon which the waters of Mountain Lake sit is made up of four different rock substrates and their corresponding fault lines  and it is fed entirely by springs and ground water from the surrounding mountaintop and basin - at nearly 4,000 feet above sea level. So, it's remarkable that a lake even exists here when you think of the implications of it lying on the top of a lot of cracks and on top of a mountain!
Water has been flowing into this mountaintop basin for 8 or 10,000 years, but it probably never stayed for very long. Then, about 6,000 years ago, the rocks at the north end of the lake slid down from the surrounding mountaintop, creating a semi-permeable "dam" at that site, resulting in a more bowl-like structure for this basin. With the new layout of the basin, outflow of water would now take longer, resulting in the creating of a pond or lake as water accumulated faster than it could leave
Recent studies show that subterranean water "loss" up here occurs at about 600 gallons per minute; every day, year around!
Come to the Conservancy Visitors Center located at the East end of the Lakeview Building to learn more about Mountain Lake, it's cycles, and the surrounding ecosystem!
| Research Papers: |
| Subterranean Loss and Gain of Water in Mountain Lake, Virginia: A Hydrologic Model |
| Authors: |
Martin Jansons
P.E., Peed & Bortz, L.L.C
Civil/Environmental Engineers,
20 Midway Plaza Drive Suite 100,
Christiansburg, VA, 24073, U.S.A.
Bruce C. Parker
Department of Biology,
Virginia Polytechnic Institute and State University,
Blacksburg, VA 24061, U.S.A.
Jacob E. Waller
Department of Biology,
Virginia Polytechnic Institute and State University,
Blacksburg, VA 24061, U.S.A. |
| Abstract: |
Mountain Lake, Virginia is a small, unique, oligotrophic, subalpine ecosystem in the southern Appalachians. Previous studies have disclosed that this lake has manifested periodic prolonged low water levels during the several thousand years of its existence. The most recent low water level occurred during the drought years of 1999-2002. Measurements of lake level, precipitation, and other meteorological data including calculated evapotranspiration in the lake basin from 2/19/02 to 8/31/03 have enabled estimation of the net subterranean water losses presumably through cracks between Clinch sandstone boulders and/or the recently discovered deep hole at the northwest end of Mountain Lake. These net losses reflect the balance between total losses and any gains from springs and boulder cracks not quantified in this study. Scuba divers have documented the existence of these cracks and the deep hole. Subterranean net water losses of about 0.04-0.05 m3/s (634-792 gpm) apparently occur year-round. |
| A Review of Research Studies at Mountain Lake, Virginia |
| Authors: |
Bruce C. Parker
Department of Biology,
Virginia Polytechnic Institute and State University,
Blacksburg, VA 24061, U.S.A. |
| Abstract: |
Mountain Lake, Giles County, Virginia (37° 27' 56''N, 80° 31'39''W) is the only natural lake of significance in the unglaciated highlands of the southern Appalachians . This oligotrophic montane lake located at 1181m (3875 ft) elevation near the summit of Salt Pond Mountain occupies a relatively small, undisturbed watershed which is about five times the surface area of the full lake. All surface outflow of water occurs at the northwest end into Pond Drain, then Little Stony Creek and the New River . Although Mountain Lake (or Salt Pond) has been known since its discovery by the British surveyor Christopher Gist in 1751 (Johnston, 1898), it remained free of published scientific studies until 1884. This first and many subsequent scientific studies of Mountain Lake are scattered widely among various journals, books, documents, and theses (often unpublished or obscure), making acquisition and compilation difficult. Yet this literature is relevant and often essential for future investigations, especially in the physical, chemical, and biological limnology, the geology, and the origin and paleohistory of Mountain Lake. Accordingly, a brief chronological review of the pertinent scientific literature on Mountain Lake with some previously unpublished new information form the author's laboratory and field records are here included. |
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