FORSYTH COUNTY, Ga. — Although it may seem as though it’s rained nearly every day this summer, experts with the U.S. Army Corps of Engineers Mobile District say Lake Lanier probably won’t reach full pool this year.
Chief of Water Management for the Mobile District James Hathorn made the forecast during a Facebook Live chat July 25, answering questions from the public regarding Lake Lanier.
Impounded by Buford Dam, Lake Lanier is a critical source of water supply for Georgia, Alabama and Florida.
“Buford Dam, Lake Lanier is part of a larger multipurpose reservoir basin the Corps must manage to balance the downstream demands for water to meet all purposes for the entire system,” Hathorn said. “Water supply, water quality, hydropower, navigation, flood damage reduction and recreation are all factors considered in managing the system.”
The lake is a federal reservoir that was built in 1958 for flood control, water supply, navigation, power production and recreation.
The lake encompasses approximately 38,000 acres with a full summer pool of 1,071 feet above mean sea level.
“The corps of engineers is not intentionally keeping the reservoir below the 1,071 foot level,” Hathorn said. “It takes a tremendous amount of rain to refill the lake to the summer level. To put it into perspective, 11.7 billion gallons of water is approximately equal to 1 foot of storage in the project.”
Their goal is to do their best to refill the reservoir every year, he said. The reservoir level has increased 4.5 feet since the beginning of the year, Hathorn said.
“Since the rainfall has returned to normal conditions, the combination of the conservative operation with an increase in rainfall has resulted in higher levels at the reservoir,” he said. “Continual rainfall above (upstream from) the reservoir needs to occur in order for us to return elevation to 1,071 feet this summer.”
The Corps manages water releases from the dam according to the recently approved Apalachicola-Chattahoochee-Flint Water Control Manuals.
“Water is captured in the winter and slowly released during summer and fall during low flow seasons where precipitation is diminished,” Hathorn said. “We capture the water and release it slowly to meet those project demands later in the year.”
The water levels at the lake are reflective of the flow into the lake from other streams, creeks and rivers, as well as withdrawals and evaporation.
Since the beginning of the year, the Corps has allowed, supported and enabled the reservoir to fill about 5.5 feet as of July 20, Hathorn said.
“For the past 12 months, the operation at Buford Dam has been to meet the water supply and quality,” Hathorn said. “There’s been sufficient storage at other downstream projects that have storage to meet the full requirements.”
The Corps monitors and releases water flow into the lake at all times, he said.
Water releases into the Chattahoochee usually occur on weekends, or the middle of the day or night to ensure there’s enough water to meet requirements downstream. Releases are affected by outdoor temperatures. Demand is higher in the summer.
“Sometimes on the weekend is slightly different,” Hathorn said. “We ensure the peaking operation takes place during the afternoon. This allows the water to be used for recreation without impacting the safety.”