Water flows from five of the eight flood gates at Folsom Dam Friday, March 18, 2016, in Folsom, Calif. Recent storms and snow runoff have caused The U.S. Bureau of Reclamation, which manages the dam, to open the gates, their first use since 2012. (AP Photo/Rich Pedroncelli)
As California faces climate change and a future with bigger storms and longer droughts, the challenges before us lead to an often-asked question: Should we make some of our existing dams bigger?
That is precisely what is happening now on the American River above Sacramento. Folsom Dam and its 340-foot-tall wall of concrete has been protecting the capital from flood since 1956. It is halfway through a construction project to increase its elevation by about 3.5 feet.
Meanwhile, upstream on the Sacramento River, a possible project with very similar engineering is at Shasta Dam. A proposal to raise the 602-foot dam by another 18.5 feet has some fresh political support, with recent legislation in the House of Representatives. But decades of steadfast opposition has made raising Shasta by any amount one of the most controversial water ideas in California.
Why does raising Folsom by 1% raise no hackles while the idea of raising Shasta 3% deeply divides the water community?
The benefits and the impacts of each possible dam are very different. And so are the politics.
Raising Folsom is a life-or-death matter to help ensure that the dam never fails. Raising Shasta is more of a balancing act of public values that pits some water benefits against environmental preservation and affected lands that are sacred to local native tribe.
The idea of raising Folsom Dam began to surface more than two decades ago as a previous flood protection alternative — a large new dam in the northern American River canyon near the community of Auburn — faded into history.
Floodplain interests in Sacramento concluded that it was politically impossible for Congress to approve a dam after multiple attempts. In 1999, the Sacramento Area Flood Control Agency, the Army Corps of Engineers and the federal Bureau of Reclamation all turned their attention to studying additional storage at Folsom and levee improvements downstream.
A single person opposed these ideas entirely because they were alternatives to the Auburn Dam. And it turns out this person was one of the most powerful members of Congress at the time, Republican John Doolittle of Rocklin, who remained in Congress until 2009 but could not stop progress at Folsom.
There is a real public safety reason to make this dam slightly taller. At the moment, Folsom is not tall enough to contain the largest conceivable storm the dam is designed to protect against, an apocalyptic event known in water vernacular as the Probable Maximum Flood. Under this theoretical disaster of disasters, the peak of flood waters would flow over the top of Folsom Dam, endangering its very survival. With this slight raise, floodwaters are predicted to stay in the spillway system, protecting the infrastructure.
Work is now underway on a series of enlargements of wing dams, an auxiliary dam and the main dam itself. Completion of the $373 million project is scheduled for 2025.
Meanwhile, at Shasta Dam, the idea of enlarging this structure has been around for decades longer than enlarging Folsom.
A taller dam has its benefits.
“More water storage, more yield, plus you are going to increase the cold water (behind Shasta) for fisheries,” says proponent Jerry Meral, one of California’s true water veterans who served under both administrations of former Gov. Jerry Brown. “It’s such a winner.”
Raising Shasta also has its impacts. While state law allows a taller Folsom Dam to slightly encroach upstream on the American River forks, it prohibits the same upstream of Shasta on the McCloud River. The California Legislature since 1989 has prohibited any state agency or department from participating “in the planning or construction of any dam.”
To a local Indian tribe that is not officially recognized by the federal government, the Winnenum Wintu, the McCloud is the most sacred of landscapes. The tribe has staunchly fought the dam.
Undeterred, Central Valley Republicans in the U.S. House of Representatives are making another run at raising Shasta. HR 215 by David Valadao, R-Hanford, seeks to break the political logjam by Congress pre-empting the state prohibition on a larger dam.
Rare is the California water project that has no opposition, particularly the raising of an onstream dam. With Folsom as a shining example, such rarity may be what it takes for a dam raise to actually happen.
Tom Philp is a Sacramento Bee columnist. ©2023 The Sacramento Bee. Distributed by Tribune Content Agency.
Originally published at Tom Philp