_We quite commonly have fall turnover at Smith Mountain Lake, usually in October, and not in all coves at the same time. we have had a severe winter in comparison to our recent winters, probably as a result of climate change effects. _This does not always happen in the spring at Smith Mountain Lake, because of the mild winters we have had in recent years. “When the weather in our region also has high winds and runoff from snow melt and /or rain the the stability of the lake water column is disrupted and may turn over with just minor temperature differences in the water. We have had very low temperatures some nights in this region contributing to this phenomenon. However in spring when we have cold nights and warmer day times, the water at the surface becomes more dense at night and may sink below the less dense water at the bottom and middle depths. _During winter the water generally becomes fairly uniform in its temperature difference from the surface to the bottom water. Of course, that is why ice floats, because the density of frozen water is less than the density of liquid water. _Water is most dense at 4 degrees Celsius (39 degrees Farenheit) and becomes less dense as it warms or as it becomes frozen. The physical process of lake turnover is caused by the warming and cooling of the lake water on the surface of the lake. The weather of course contributes to this turnover occurrence and is generally dependent on the climate in the region. _ I have observed that phenomenon before in Smith Mountain Lake. Carolyn Thomas of Ferrum College, a professor of environmental sciences who also heads Smith Mountain Lake_s annual Water Quality Monitoring program. The spring turnover is the most likely cause at this time, _ said Dr. “Many processes contribute to the turbidity of the water in most lakes and especially in a reservoir as large as Smith Mountain Lake. Dissolved oxygen at the bottom of the Lake is the single most important water quality parameter that drives nature’s cleansing process, according to scientists. It also revives and replenishes the anerobic bacteria population so they can start decomposing organic litter that has built up. The oxygen drives off toxic gases the build up in the substrate of the Lake. It is nature’s way to supplying oxygen-rich water from the surface layer to the stagnant water at the bottom. Although created by man as a hydroelectric impoundment, the Lake also is governed by the oft-mysterious performances of Mother Nature, and “turnover” is one of them. Inversion literally breathes life into the Lake, itself a dynamic, ever-metamorphosing and magnificent organism. Inversion does not occur all at once, like flipping a pancake, but takes place sporadically in separate areas at different times and water temperatures fluctuate in spring and fall. “I agree,” with Robert Hallock Jr., a Bedford County reader who called the Smith Mountain Eagle recently about the possibility of an inversion occurring. “What we are most likely witnessing is “Lake turnover,” or inversion,” said Pam Dinkle, Lake Management and Project coordinator for the Tri-County Lake Administrative Commission (TLAC). What is happening, rather than siltation of the water, could be a twice-a-year phenomenon and natural cleansing and aerating process called inversion, “Lake Turnover,” or “rollover.” In waters that deep, sediment from runoff does not show up at the surface. Some have attributed the Lake’s murky shade to runoff from melting snow packs upstream, but according to experts, that is not entirely so, especially in the main channel at Hales Ford, where the water is more than 110 feet deep. Lake residents and commuters who cross Hales Ford Bridge each day may have taken note in the last week or two of the hue of the blue-brown waters beneath the span. Natural phenomenon observed as the Lake “turns over” YOU MAY JUST WANT TO TAKE OUT A SUBSCRIPTION TO THE PAPER! GO TO THE WEBSITE AND CHECK IT OUT. IT IS A GREAT LOCAL WEEKLY NEWSPAPER PUBLICATION ABOUT ALL SORTS OF PEOPLE, EVENTS, AND NEWS CONCERNING THE SMITH MOUNTAIN LAKE AREA. THE FOLLOWING ARTICLE WAS PUBLISHED IN THE Smith Mountain Eagle ON MARCH 10,2010.
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