Georgia Power's North Georgia Hydro Group
In the early 1900s, the Georgia Railway and Power Company (predecessor to the current Georgia Power Company) built a series of dams on the Tallulah and Tugalo Rivers to supply power to Atlanta.We bagged 'em all on a Dam Quest based at Black Rock Mountain State Park.
The northern most dam is Burton, impounding Lake Burton. It originally was meant for storage for the Tallulah Falls plant, but later a plant was added locally producing 6 megawatts. It is a concrete gravity dam, 128 feet high and 1,110 feet long, and was finished in 1919.
The next is Nacoochee Dam, impounding Lake Seed. It was completed in late 1926, and is a gravity dam standing 75 feet high and 490 feet long. It produces about 4.8 Megawatts of power.
Further downstream is Mathis Dam, impounding Rabun Lake, and supplying the Terrora Power Plant (don't ask me, I didn't name them!). This dam is proudly billed as an "Ambursen type construction" dam... which is basically a thin sheet of concrete reinforced with connected buttresses on the downstream side. If you look at the dam, it is a little different from any others we have seen. Outside the spillway, the construction appears to be a bunch of chambers as opposed to solid concrete. Completed in 1915, the dam stands 108 feet high and 660 feet long.
Originally built for the same purpose as Burton, to store water for the Tallulah Falls Plant, it was later decided to add a plant at the dam. Eventually that was abandoned in favor of locating the plant just behind the Tallulah Falls dam, and take advantage of an additional 100 feet of head. So now Mathis diverts the flow into a mile long tunnel to the Terrora Power Plant, with a capacity of 16 Megawatts
This is the Terrora Power House and Switchyard. The penstocks feeding it are seen below.
This is the Tallulah Falls Dam. As you can see, it is right at the bridge for US 441. In fact, you can't see the dam as you drive over the bridge. This is another diversion dam: the water is sent through a 6,666 foot (thats what it said!) tunnel to the surge chamber above the power house. The dam is 126 feet high and 426 feet long and was completed in 1912.
Coming back from our Cherokee Trip in April 07, we caught it spilling. Georgia Power schedules several spills every year, ranging from 200 cfs "aesthetic" spills to 700 cfs for rafters. This was a 700 cfs spill. Since you can't see the dam from the road, we actually drove by it, until Jan noticed a parking lot reserved for "Rafters Only"! A quick U-turn, and here you go!
The total head is over 600 feet, and the plant is capable of 72 Megawatts. For comparison, the combined capacity of the rest of the group is about 94 Megawatts. Altitude makes a difference! Also notice the railway next to the penstocks. This was used during construction, and is still used today for access to the plant. Unfortunately, it is not open to the public, but at least access is allowed to the upper parking area. The gates are closed and locked when the crew leaves work for the day at about 3:00 PM, so be aware of the time. We were able to talk to one of the guys, and he gave us a brochure, which is the source of most of our information about the group. We're very appreciative because we were unable to find another copy of the brochure anywhere, and we fear it may be out of print now.

One of the most breathtaking views is that of the Tugalo Dam. As you can tell from the picture, it is off the beaten path. There is a one lane unimproved access road back into the woods, not in too bad of shape up to this point; the old family truckster negotiated it without difficulty. As you make the drive, you approach a "shinbone" ridge, and you can tell it by the increasing visibility. All of a sudden you pop out into the open, and there it is! This view shows the lake and the convergence of the Tallulah and Chattooga Rivers to form the Tugulo River. The head at the dam is almost 150 feet, and the plant is capable of 45 Megawatts. The dam stands 155 feet high and 940 feet long, and was completed in 1923.
You can continue on the road as it descends into the gorge to get to the base of the dam and the power house. Its a little rougher because of the descent, but the Caravan made it with no problems. Georgia Power also maintains a campground there. There is a public restroom with running water, but no other facilities.
Finally, we get to Yonah Dam. Believe it or not, this was the hardest one to find, because we didn't have good maps at the time. After criss-crossing the river, we finally stumbled across Yonah Dam Road (duh!), drove about 5 miles upstream, and thar she blows! In the bag now, Yonah has about 70 feet of head and is capable of 22.5 Megawatts. The dam is 90 feet high and 980 feet long, and was completed in 1925.
The Tugalo River flows into Lake Hartwell and becomes part of the Savannah River, the border between Georgia and South Carolina, and empties into the Atlantic Ocean.
While doing other research in June of 2001, we discovered there is now another development that is considered part of the North Georgia Hydro Group, the Estatoah Development, near Mountain City. It must be a small one, since its capacity is only listed at 240 Kilowatts... about a quarter of a Megawatt. But we'll have to add it to the group when we get a chance.