California’s stubborn drought could force Santa Barbara County water agencies to re-evaluate the way Lake Cachuma’s water is allocated, since the reservoir that’s expected to last through a seven-year dry spell is emptying quickly after just four.
“Looking back now I think we should have made some reductions sooner than what we did on this go-around,” said Tom Fayram, deputy director of the county Public Works Department.
The entitlement amounts — how much water each agency can take from Cachuma each year — haven’t changed since 1995, when the current contract with the county went into effect. Given silt accumulation, the reservoir has a current capacity of 188,000 acre·feet of water, with an acre-foot roughly equivalent to the annual water use of an average family of four.
The agency allocations weren’t cut until the region was several years into a drought. Now, officials from various water agencies are starting to talk about smaller entitlements in the future.
“We can’t have a lake that lasts four years,” Fayram told Noozhawk.
“Who knows if we’ll continue into the drought or El Niño will help us, but what we do know is we have suffered through seven-year drought cycles before and it’s really important to last,” he added. “We have to do things a little differently going forward if Cachuma is going to be our mainstay water source.”
The Public Works Department is conducting a study of options for future water allocations, since the current contract expires in five years.
“Part of the problem is the allocations set up with the first contract — 25,700 acre-feet per year — was put in place but there was no mechanism to reopen and reanalyze that because things changed over time,” Fayram said.
This time, Fayram wants to include a way to reopen discussions every few years, so the allocations aren’t locked in for another 25-year period.
There are two water-delivery models, both calculated using the worst past drought period. The 1945-1952 drought has been the model, but the current drought could be the “new worst,” Fayram said.
The county could use a safe yield model, in which agencies receive a smaller, consistent amount each year, or allocate more water in abundant years and incrementally less in dry years, so agencies have to make up for shortages in the later years of a drought.
Monthly evaporation rates are significant for Cachuma, with more than 1,000 acre-feet evaporating this July. If the lake is full, the surface area is twice as big as it is now, and evaporation during summertime can be 2,000 acre-feet per month, Fayram said.
“It’s a Catch-22, because if we keep the lake full to keep the water for longer, it also evaporates more,” he said.
Carpinteria, Goleta and Santa Ynez are turning more to their groundwater basins as surface water dries up, while Santa Barbara voted to reactivate its seawater-to-potable water desalination plant. Montecito desperately wants in on that facility and is simultaneously pursuing its own, just in case.
Besides the daily deliveries for the South Coast, which range from 50 to 80 acre-feet of water per day, reservoir water is released downstream of Bradbury Dam to replenish groundwater basins for Santa Ynez River water rights holders.
This year’s downstream releases start Monday and will take out 8,000 acre-feet over a period of two months, or about 300 acre-feet per day. Those releases will drop the lake level about eight feet, Fayram said.
As of July 31, Cachuma was at 24.6 percent capacity and its elevation — relevant for the gravity-fed system that delivers water to Goleta, Santa Barbara, Montecito and Carpinteria — is dropping.
The Cachuma Operation and Maintenance Board, which manages water deliveries to those South Coast agencies, commissioned an emergency pumping facility to keep water moving after the lake level drops too low for the current system.
A pumping barge will draw water into the intake tower, which is 2 miles east of Bradbury Dam, and into the Tecolote Tunnel through the Santa Ynez Mountains.
With the downstream releases starting Monday, it’s expected the pumping will start later in the month, COMB general manager Randy Ward said.
Included in the COMB plan is the option to move the pumping barge to a deeper part of the lake when necessary, relocating near Lake Cachuma County Park. The recreation area — which prohibits swimming in the lake — is open to camping and day-use visitors, and the sites were packed last week as people bicycled, boated, kayaked and hiked around the western end of the lake.
As of June 30, $5.4 million has been spent on the project and another $2.7 million is expected for the current fiscal year for operation and maintenance, electrical connections and construction for relocating the pumping barge system.
The pumping project was finished last year but conservation from water users and imported water have kept the lake levels high enough to delay the need, said Ward, who retired from COMB on Friday.
“This thing is not without cost to operate and the longer we’re able to gravity feed, the more time we have to get us into the winter and have that lake level rise a little,” he said. “Cross your fingers and knock on wood.”