Dry weather causes Smith Mountain Project flow reduction

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By John Barnhart

Appalachian Power is letting a little less water out of Smith Mountain lake due to dry weather.

According to John Shepelwich, a company spokesman, the power company seeks to balance the needs of people who use the lake with the needs of people downstream from the hydroelectric project. The project's license from the Federal Energy Regulatory Commission (FERC) specifies a minimum outflow from the project of 650 cubic feet per second (cfs). There is a process that allows the company to get a variance on this outflow if it threatens to lower the lake level too much. The lake is a major tourist resource and the water level becomes a safety issue for the lake's recreational users if it drops too much.

The process to ask for a variance was triggered on July 23, at 6 a.m., when the lake's adjusted elevation reached 793.38 feet. Adjusted elevation indicates the level that the lake would be at if water currently in Leesville Lake was pumped back into Smith Mountain Lake. This is nearly 2 feet below Smith Mountain Lake's full pond level of 795 feet. Water flow into the lake had been dropping for some time and, by that date, the power company was releasing more than three times as much water from the lake as was flowing in.

The necessary variance is issued by Virginia's Department of Environmental Quality (DEQ). Shepelwich said that the Smith Mountain Project's reservoir manager, Teresa Rogers, has been holding weekly conference calls with lake stakeholders, including DEQ, on the lake's water level, so DEQ was aware of the need.

Shepelwich said that, in order to get the variance, Rogers had to make a formal written request to DEQ. The variance is good for 45 days, or until the lake's adjusted water level reaches 794 feet, whichever comes first.

Under the variance, Appalachian must release a daily average of 500 cfs of water from the Leesville Dam. Water flow in the river, as measured at Brookneal, must be at least 600 cfs. If waterflow hits 700 cfs, the power company will lower its water releases to bring the flow back down to 600 cfs, although releases from Leesville can't drop below 400 cfs. Shepelwich notes that Staunton River has water flowing into it from other sources between the Leesville Dam an Brookneal, which could affect the flow at that point.

The variance also requires a weekend change in water releases. The release will be modified on weekends so that a flow of 650 cfs, measured on the river at Long Island, begins at or near 8 a.m. on Saturdays during the variance period and continues until 8 p.m. the following Sunday. For Labor Day weekend, releases of 650 cfs will continue until 8 p.m. on Monday.

Shepelwich said that, based on weather forecasts, more rainfall is expected in the watershed that feeds Smith Mountain Lake and officials expect waterflow into the lake to be improved before the variance period ends. If this doesn't happen, the power company would have to ask for an additional variance. This would have to come from FERC. According to Shepelwich, the power company had to do that last year.

Appalachian Power posts flow and water levels on the Internet at www.aep.com/environmental/recreation/hydro. This gives data for Smith Mountain Lake and the company's other hydro projects.

The Smith Mountain Project is a pumped storage hydroelectric project that smooths out the power load on Appalachian's system. During high demand hours, water is released from the lake, turning turbines that run generators at Smith Mountain Dam before entering Leesville Lake.

When power demand is low, electrical power is used to pump water from Leesville Lake back into Smith Mountain Lake. This keeps the power company's other plants operating at their optimum level for efficiency by soaking up excess electrical energy and storing it in the form of water pressure for later use. The dam's generators can crank up from zero to full power in a matter of minutes.

Leesville Dam also has turbine generators and some of the water leaving Leesville Lake is used to generate electricity. The entire Smith Mountain project can generate 636 megawatts of electricity.

Appalachian Power serves three states and is a unit of American Electric Power.