With the recent dumping by three successive storm cells, the City of Santa Barbara’s Gibraltar Reservoir is poised to spill, meaning runoff water should soon start pouring downstream and into Lake Cachuma in significant quantities for the first time since 2011.
As of Tuesday evening, Gibraltar — by far the smaller of the two reservoirs from which the city draws — is about two feet from spillage, meaning it could overflow anytime. With Gibraltar overflowing, all the water it had previously short-stopped — thick with sediment from recent fires — can now run towards Cachuma, which is reportedly 11 percent full. Last week, it was at nine percent of storage capacity.
Once Gibraltar spills, Cachuma can impound inflow and runoff at a much faster rate. But as usual with this year’s rains, the news looks rosier than it immediately is. First, the most recent storm proved substantially less bountiful than predicted. Second, none of the water flowing into Cachuma can be used by the member water agencies drawing from the dam until there’s a live stream flowing from the base of Cachuma down the main stem of the Santa Ynez to the ocean. Even then — according to byzantine water accounting rules — another 4,000 acre-feet worth of water will have to be set aside for downstream users, and another 2,000 acre-feet set-aside to replenish accounts created for steelhead restoration efforts, before South Coast water agencies can start availing themselves to the accumulated run-off now collecting in Cachuma.