Tropical storm could bring drought relief

Published 12:00 am Wednesday, December 2, 2009

By Mark Wineka
mwineka@salisburypost.com
Meteorologists are hoping Tropical Storm Fay in Florida eventually takes a path into North Carolina and does a lot of damage ó not to property, but to the drought Piedmont counties are mired in.
Rainfall from a good tropical storm might go a long way toward replenishing waters in the mountains and foothills that feed the Catawba River and, more locally, the Yadkin and South Yadkin rivers.
Salisbury, for one, relies on the Yadkin River for its water supply.
Fay is expected to be over western South Carolina by Friday morning and over North Carolina’s mountain region Saturday, but the amount of rain it will bring is hard to gauge, said National Weather Service meteorologist Doug Outlaw in Greer, S.C.
The five-day forecast for rainfall projects 10 inches or more in the Charleston to Savannah area, Outlaw said. The projection currently is 2 to 3 inches over the western Carolinas, but three times that could fall “if it were to come straight up and across the western Carolinas,” he said.
Western and central North Carolina also can expect substantial rain, Outlaw said.
Fay was headed for the Florida Keys on Monday and could become a hurricane as it barrels toward the west coast of Florida.
Outlaw said some groundwater levels are at historic lows and “a big rain like this could give great benefits to the lakes and reservoirs and the ground water.”
Last week on the Yadkin River, water flow reached its lowest point of the summer, but locally it still has a way to go to reach the nadir recorded in the 2002 drought.
The water flow past the Yadkin College station on the river last week was about 300 cubic feet per second, or 195 million gallons a day. (The average flow should be about 1,800 cubic feet per second.)
A Saturday night storm burst recharged the Yadkin to just more than 500 cubic feet per second, or 320 million gallons a day. But that spike may not last long.
Jeff Jones, planning and research manager for Salisbury-Rowan Utilities, recalled Monday that flow in the Yadkin River dipped below 200 cubic feet per second in August 2002.
High Rock Lake, the first of four reservoirs that make up Alcoa’s Yadkin Hydroelectric Project, also was 24 feet below full pond in July 2002 when Alcoa managed its release of water downstream much differently. High Rock Lake was 6 feet below full pond Monday ó the lowest point all summer.
The Yadkin Drought Management Team, made up of Alcoa and other river stakeholders in North and South Carolina, meets regularly to respond to drought conditions.
The Federal Energy Regulatory Commission has granted the team two variances this summer in relation to how much water Alcoa releases downstream from its project. Alcoa started out releasing 1,400 cubic feet of water per second but was allowed to change that to 1,000 cfs, then 900 cfs.
It’s a record low drawdown for Alcoa.
“Through 2007 and 2008,” Jones said, “Alcoa has done a much better job of managing the lakes.”
Meanwhile, virtually all of Rowan County (except its southeastern tip) remains in “extreme” drought conditions, according to the U.S. Drought Monitor. Jones says the Yadkin River Basin is essentially divided with half of its area in the “extreme” drought category and half in the “severe,” which despite its name is not as bad.
There is one category ó “exceptional” ó which is worse than extreme.
The mountains of North Carolina are in the exceptional drought category ó that is 18 counties in the southwestern portion of the state.
The U.S. Geological Survey reports that streamflow in the French Broad River at Asheville has reached the lowest level since 1895. There, it is about 188 cubic feet per second, or 121 million gallons a day.
The U.S. Geological Survey says minimum record stream flows also are being recorded in sections of the Yadkin and Catawba river basins.
Salisbury has remained under voluntary conservation measures (Level 1) since last fall, although the Yadkin River water level above its intake grates has remained above the line when voluntary conservation is supposed to kick in.
Jones said the Yadkin is 35 inches above the voluntary line, though that is the lowest level this summer.
At the drought’s worst in 2002, the Yadkin River level was 18 inches above the voluntary conservation line.
Once the water level reaches the Level 1 line, the city still has 21 inches of depth to work with before its ability to deliver water would become impaired, Jones said.
“We still have a lot of safety factor built in,” he said.
Winston-Salem recently returned to voluntary conservation measures based on the lower Yadkin River water flows.
National Weather Service figures show the rainfall deficit for the year so far is 10.69 inches in Asheville and 11.06 inches in the Greenville-Spartanburg area. Charlotte’s deficit is 5.83 inches.
South Carolina state climatologist Hope Mizzell said a return to normal rainfall patterns is needed to break the drought, not just a big rain event.
“Certainly, a tropical storm bringing us some rainfall without the severe weather would be welcomed and would help,” she said.
Last week, South Carolina Gov. Mark Sanford sought a federal drought disaster declaration for all but two of the state’s counties. Sanford said more than 30 percent of this year’s harvest of corn, hay and pasture crops has been lost because of drought.
About a fourth of South Carolina suffers from extreme drought, the worst level on the state’s drought scale.
The Associated Press contributed to this story.