by Chris Scalley
How can the Chattahoochee be cold enough for trout in the hot Georgia summer? It’s all about water storage! Let’s begin with Lake Lanier, which is huge with 38,000 surface acres and over 700 miles of shoreline! It takes a drop of water typically two years from the time it enters the lake until it exits the Buford Dam.
We always have to remember that the past winter season cold weather helped to create a tremendous layer of cold, dense water that gravitates to the lake floor. Even though the lake surface temperature is 78F in mid-summer, if you were to dive just 15 feet you would feel a dramatic change to cooler water. The warmer, less dense summer water molecules stay higher in the water column and the denser, cold winter water molecules gravitate to the depths of the lake. It just so happens that the Buford Dam “penstocks” or raceways, where the lake water exits the base of the Dam, are about 130 feet deep. The average annual water temperature from Buford Dam is 56F.
In 1957 the Army Corps of Engineers designed and constructed the dam for flood control and hydropower. Little did they know the tailwater would be one of the best trout fisheries in the nation. So while your catching wild and stocked trout on the Chattahoochee in the suburbs of Atlanta this summer, just briefly think about how cold last winter was.