Q: I don't understand how the level of Lake Lanier is managed. The lake level drops even when there is rainfall in the previous 24 hours. It sometimes drops less when there is no rainfall than when there is some. As of Oct. 20, the lake was more than 10 feet below summer level.
-- Ronald Wimer, Loganville
A: Several factors drive the releases from Buford Dam and the water level of Lake Lanier. During the week, the primary purpose of the releases is to balance the system's storage reservoirs, meet the Jim Woodruff Dam minimum flow requirement for endangered species and ensure metro Atlanta's water supply and water quality flows, E. Patrick Robbins, the chief of legislative and public affairs for the U.S. Army Corps of Engineers, Mobile District, wrote in an email. On weekends, the primary purpose of Buford Dam and Lake Lanier is to meet the water supply and water quality flows for metro Atlanta. Hydropower needs and requirements are met through the current primary purposes. "As for rainfall, it is important to note where the rain falls," Robbins wrote. "The drainage basin that feeds Lake Lanier is to the north, northeast and northwest of the lake. Rainfall on either the east side or the west side drains east or west away from the lake and rain on the south side drains south." Lake Lanier has the smallest drainage basin in the Apalachicola-Chattahoochee-Flint (ACF) River system because of its location in the northern part of Georgia and how the topography dictates the size of the basin, Robbins wrote.
Andy Johnston wrote this column. Do you have a question about the news? We’ll try to get the answer. Call 404-222-2002 or email q&a@ajc.com (include name, phone and city).
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