LAWRENCEVILLE - A faulty gauge has caused the U.S. Army Corps of Engineers to unknowingly release billions of gallons of water from Lake Lanier, which is Gwinnett County's main water source.
As a result, the lake at Gwinnett's northern tip is actually two feet lower than earlier reported by the federal agency in charge of the 38,000-acre impoundment.
Instead of three feet below full pool, the lake is five feet short of being full, the Corps reported over the weekend after discovering the problem on Friday.
"We were actually releasing more water than was necessary during the 52-day period because we thought we had more water to release," said Corps spokesman Pat Robbins.
Two weeks ago Georgia officials criticized the Corps of Engineers for not keeping more water in Lake Lanier and warned its water levels could reach record lows this summer and cause water shortages in metro Atlanta.
Gov. Sonny Perdue and others said too much water was being released at Buford Dam to benefit endangered species downstream in Alabama and Florida, when instead it should be stockpiled for the summer dry season.
A calibration error in a gauge used to monitor the amount of river water flowing into the lake led to the mistake, Robbins said.
The Corps' current strategy is to release the same amount of water that enters the lake from the north Georgia mountains. Since the gauge gave an inflated reading, the agency was letting more flow through Buford Dam than was coming in from upstream.
The gauge was off by only four-tenths of an inch, according to the Corps. That translates into a half-inch of water being released each day over a 52 day period, the agency reported.
However, when a half-inch of water is spread across thousands of acres of lake surface, it can add up. One person familiar with the lake said 2 feet of water in Lanier equals roughly 20 billion gallons of water.
On its peak day this year, Gwinnett County drew 110 million gallons of water from the lake for its residents and businesses.
A spokeswoman for Gov. Perdue said the faulty lake reading backs the state's earlier contention that more water should be stored in Lanier and other lakes for Georgia's use.
"We've been warning the Corps that they were releasing too much water and now it appears that we were right and further more, the situation is worse than expected," said Perdue spokeswoman Heather Hedrick.
The revelation that Lake Lanier is lower than thought will have no immediate effect on Gwinnett County water customers, said county Water Resources Director Frank Stephens.
Gwinnett will monitor the situation and, if necessary, tighten outdoor water use restrictions that were made permanent in 2003, Stephens said.
"It certainly does present things in a new light, and I think we will stay in communication with both (the state Environmental Protection Division) and the Metro North Georgia Water Planning District," Stephens said.
"If either of those report that communities need to go to the next level of outdoor water use restrictions, we will move accordingly."
Most of Georgia is experiencing drought conditions, said state Climatologist David Stooksbury.
Gwinnett County is in moderate drought, meaning plants and trees will start wilting and appear sickly, Stooksbury said.
Water is already receding from boat docks that border Lake Lanier.
Although state officials warn Lake Lanier will reach historical lows this summer, the Corps says it will drop no lower than it did during a four-year drought that ended in 2002. In 2001 the lake receded to 15 feet below full pool.
The anticipated lake levels will have "critical impacts" on electricity generation at Buford Dam and recreation at Lake Lanier, Robbins said.