As a rainy December comes to close, nearly all Northern California reservoirs were still drier than historic averages for this time of year, according to data from the California Department of Water Resources.

But the precipitation still gave several reservoirs a boost from the beginning of the month.

Of seven major reservoirs in Northern California, three currently have more water than they did a year ago: Lake Mendocino, up 7%; Lake Oroville, up 2%; and Hetch Hetchy, up 15%. That’s an improvement from mid-December, when only Hetch Hetchy held more water than a year ago.

That reservoir, which supplies much of the Bay Area, is also the only one to hold more than its average capacity.

While the rain certainly helps, in Hetch Hetchy’s case, much of the additional water can be chalked up to conservative water management practices at the reservoir, Michael Anderson, a state climatologist with the California water department, explained.

While not quite enough to bring levels up to historic averages, the December rain did boost water levels at six of the seven reservoirs, with Lake Mendocino seeing the biggest jump, from holding 17% of its total capacity last month to 31% this month.

Trinity Lake, located in Trinity County north of Redding in Shasta County, has remained steady in its water supply since last month at 29% of capacity, down from 51% a year ago. Its historic average for this time of year is 60%.

As a rainy December comes to close, nearly all Northern California reservoirs were still drier than historic averages for this time of year, according to data from the California Department of Water Resources.

But the precipitation still gave several reservoirs a boost from the beginning of the month.

Continue reading the article from the San Fransisco Chronicle here.