This article from the Sacramento Bee details all the reasons we need extra water storage above Folsom Dam, specifically, a redesigned Auburn Dam able to withstand the earthquakes, funding, and other issues that derailed the original.
Northern California’s El Niño winter has been on pause lately, with this week’s storm representing the only significant rainfall so far in February. Yet federal dam operators recently increased the flows out of Folsom Lake by thousands of acre-feet a day as a precaution against flooding. They did so even as the reservoir sat 40 percent empty.
The dam operators weren’t acting on their own initiative. They were adhering to a nearly 30-year-old manual, drawn up by the U.S. Army Corps of Engineers, that requires them to release water when Folsom Lake rises to a specified height. The requirement holds even if no major storms are forecast and the state is trying to conserve water during the fifth year of an epic drought.
Similar operating manuals, all created by the Corps, govern flood-control releases at 54 dams in California. The majority haven’t been updated since at least the 1980s; Folsom’s manual was last updated in 1987.
Now, a small but growing chorus of Sacramento-area water managers and hydrology experts says it’s time to rework the guidelines at Folsom and other reservoirs to permit more flexibility on water storage, particularly given a warming climate expected to bring more frequent and longer dry spells.
“When April rolls around, it’s … likely we’ll look back and say, ‘Gosh, I wish we hadn’t made those releases,’” said Jay Lund, director of the Center for Watershed Sciences at UC Davis.
The ramped-up releases didn’t occur in a vacuum; they followed a remarkable surge in which the lake’s water level tripled in less than two months. Officials with the Corps said flood safety remains a paramount concern, particularly with hundreds of thousands of Californians living on floodplains below dams.
Christy Jones, chief of water management in the Corps’ Sacramento district, said every dam’s flood-control manual provides some wiggle room to account for recent weather patterns, forecasts and hydrological conditions, but reservoirs must have ample space during the wet season to ward against unforeseen floods.
“If they say that (a storm) is going to be really small, and it ends up being much bigger than what they forecast, then we don’t we keep enough space in the reservoir, then we’ve not done our duty to help reduce that flood risk downstream,” she said.
The increase in water releases from Folsom, which began Feb. 5, spilled enough water to supply the Sacramento region for weeks, much to the chagrin of water managers who remain under orders from the state to meet stiff conservation targets. They say it’s difficult to get people to take shorter showers and rip out their lawns when extra water is flowing out of Folsom even amid prolonged forecasts of sunny skies.