This past week’s storm not only brought Montecito 3.46 inches of much needed rain and without causing debris flows in the Thomas Fire burn scar, but generously added to the water supply at Jameson Lake.
Thursday’s rain in particular fell over the Santa Ynez upper watershed and was concentrated over Jameson Lake, where the rain gauge recorded 6.19 inches of rainfall for the previous 24 hours around midday on Thursday, according to a Montecito Water District news release.
That was about 5 inches more rainfall than measured during the same time period at the water district’s office.
As the News-Press reported Friday, Santa Barbara County Public Works recorded that Jameson Lake accumulated the highest rain total over a seven-day period with 9.46 inches, ahead of the second highest San Marcos Pass, which received 9.4 inches.
By Thursday, Jameson Lake was filled to 2,217 feet and rising, 7 feet below its storage elevation of 2,224 feet. Rainfall between Sunday and Thursday deposited approximately 1,250 acre-feet of runoff into the lake, which increased its total storage to around 4,300 acre-feet, 83 percent of its 5,144 acre-feet capacity.
That does not mean the additional water will be treatable, as each rain since the Thomas Fire has deposited ash and debris into the lake, threatening water quality and making treatment difficult.
Water deliveries from Jameson Lake were indefinitely suspended after the Thomas Fire while the water district works on a treatment improvement project at its main treatment facility.
According to the news release, due to runoff and nearby streams, the lake level will continue to rise even without rain.
A future rainstorm could cause the lake to spill, in which case the water would flow down the Santa Ynez River toward Gibraltar reservoir. Spills from Gibraltar then go to Lake Cachuma, a primary water resource for the Montecito Water District and the entire South Coast.
Santa Barbara County remains in its winter rainy season and more storms are likely.