This winter has started out as a wet one, but even if the rain tapers off, Santa Barbara can meet the water demands of its customers through 2022 with existing supplies, according to city staff.
It’s been more than eight years since Lake Cachuma filled up and spilled, and groundwater basins all over Santa Barbara County are at historically low levels after being heavily pumped during the long drought.
Groundwater well pumps are off to help basins “rest,” and it will take an estimated five years for the basins to recover from the drought, water supply analyst Dakota Corey told the city’s Water Commission at Thursday’s meeting. That’s how long it took after the drought in the early 1990s, she said.
Another consequence of heavy groundwater pumping is the threat of seawater intrusion, since Santa Barbara’s largest basin is connected to the ocean. Monitoring wells check chloride levels, which have been rising since pumping increased around 2014, according to Corey.
“The closer it gets to our production wells, the more concerned we are,” she said.
Santa Barbara will use surface water supplies — from Lake Cachuma and the State Water Project — to meet demand in the next two water years, as well as desalination plant-produced water and recycled water, which is used for some irrigation customers.
City residents are still conserving water — using 30 percent less than they did in early-drought 2013 — which is a trend seen all over the South Coast.
Corey said the city does not anticipate purchasing supplemental water supplies or expanding the desalination plant’s capacity to meet water demand through the 2022 water year, which ends in September.
The desalination plant, which converts seawater to potable water, produced 2,993 acre-feet in the 2018-19 water year, about a third of the city’s total demand for water.
While it was originally built in the 1990s, it was mothballed when heavy rains hit the region, and the city spent more than $70 million to get it operational for the most recent drought.
Its long-term role as a city water supply “will need to be revisited” when the city updates its water management plan in 2020, according to city staff.
Santa Barbara is negotiating to sell the Montecito Water District 1,432 acre-feet of water a year, but it has enough excess supplies to meet the demands of the agreement — if it’s ratified — through 2022 without expanding the desalination plant, Corey said.
The city also needs to pay back its outstanding water debt from years of supplemental water purchases during the drought.
Wildfire Effects on Local Reservoirs
Santa Barbara County was labeled “abnormally dry” in mid-November, but a series of storms pushed the region out of any drought condition.
As of Friday, the county had 142 percent of its normal-to-date rainfall, helped by the weekend storm and the Christmas rainfall that prompted flood advisories.
Lake Cachuma was 72.4 percent full, the city’s Gibraltar Reservoir was 29.9 percent full and Montecito’s Jameson Reservoir was 82.3 percent full. All three South Coast reservoirs have lost storage capacity after wildfires burned across their watersheds.
Gibraltar has about one-third of its original capacity, after being heavily affected by siltration following the 2007 Zaca Fire, the 2016 Rey Fire and the 2017 Thomas Fire, according to the city’s water supply report.
The city doesn’t know the full impact of the Thomas Fire yet, but a study showed a 654-acre-foot loss in capacity between August 2017 and August 2018.
Winter storms helped flush out some of the sediment, leaving its estimated current capacity at 4,583 acre-feet.
Likewise, recent wildfires have burned two-thirds of Lake Cachuma’s watershed (about 180,000 acres), which affected water quality and sedimentation.
The Cachuma Operation and Maintenance Board is studying options to manage the burned watershed, including erosion control and in-lake treatment, city staff said.
Water quality effects from the Thomas Fire made Jameson Reservoir unusable as a supply for more than a year, and the blaze burned down the Juncal Dam caretaker buildings.
— Noozhawk managing editor Giana Magnoli can be reached at firstname.lastname@example.org. Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.