“All dams leak” were three interesting words I heard prior to taking a tour of the inside of Norris Dam located at Norris, Tenn. This dam was the first one constructed by the Tennessee Valley Authority (TVA) in 1933.
While it’s not the largest of the TVA dams, standing 265 feet below it gives one the sense of the awesome force of what it’s holding back.
My guide unlocked an iron door and led me into the belly of the dam. We slowly walked through a short tunnel to a “T” junction. Here we entered a longer corridor running the entire length of the dam. This was just one of four corridors strategically located inside the dam. It reminded me of the Egyptian pyramids in a way. Tunnels located throughout a solid structure of concrete, all built with a purpose in mind.
A small channel of water trickled along one side of the corridor. “This is where water trying to find its way under the dam emerges,” the guide explained. “It flows up from pipes buried deep below.” This supported his earlier statement that all dams leak.
Folsom Dam and Reservoir, Mormon Island Auxiliary Dam and eight earthen dikes make up the Folsom Facility that’s managed by the U.S. Department of Interior, Bureau of Reclamation. Reclamation and the U.S. Army Corps of Engineers are in the final phase of a $900 million project at the dam.
Phase four, the auxiliary spillway, is the last piece of a modification deemed necessary to reduce hydrologic (overtopping) of the dam, seismic (earthquake) and static or seepage events. Remember, all dams leak and Folsom is no exception.
The concerns being addressed have a low probability of occurring in any given year but because of the large population downstream, the modifications are necessary for improved public safety.
Viewing the lake now, it’s hard to imagine why the spillway is needed and I doubt anyone living today will ever see it in action. In fact, the project is a 200-year insurance policy. There’s a one-in-200 chance the spillway will ever be used.
If the water level in Folsom Lake does reach the brim, it will flow through a 1,100-foot approach channel that will funnel it from the lake into the spillway. From there a control structure with six submerged gates will work in concert with the gates on the main dam to control the water released. It would then flow through the 3,027-foot long spillway chute down to the American River.
This final phase of the project is scheduled to be completed in late 2017.
Flooding downstream before then is highly unlikely. Drought conditions have resulted in less than 18 percent capacity and getting lower by the day. Parts of the lake bed are now exposed that haven’t been for many years. This is giving curiosity seekers a rare chance to explore old stone foundations and the remnants of the town of Red Bank.
If you own a metal detector, here’s an opportunity to find my sunglasses lost while boating on the lake two years ago. Not to mention jewelry, fishing lures or other valuables accidentally dropped off the side of pleasure craft over the years.
The El Dorado County Sheriff’s Department is currently searching for something more meaningful as they try to locate the wreckage of a plane that plunged into the lake in 1965. The remains of three of the four passengers were never recovered.
In the event this record-breaking drought drags on and rationing water becomes necessary, try to remember all dams leak, unless of course it’s one with no water behind it. Folsom Lake appears heading in that direction.
Richard Esposito is publisher of the Mountain Democrat. His column appears each Wednesday.