California's Biggest Reservoirs Filling After Parade of Wet Storms

You've seen lots of rain out the window over the past 10 days or so, and you're wondering what impact the storms have had on the reservoirs that most of California depends on.

Well, El Niño has delivered.

The series of wet storms that began the week before last brought very heavy rain to the upper Sacramento River and Feather River watersheds, which feed the state's two largest reservoirs, Shasta Lake and Lake Oroville, respectively. And the reservoirs are rising fast.

How much rain merits the description "very heavy"?

Bucks Lake, a notably wet locale in the Feather River watershed in the northern Sierra, has gotten 26.12 inches of rain in the past 11 days. Sims, site of a roadside weather station along Interstate 5 north upstream from Shasta Lake, reports a 12-day rain total of 20.72 inches.

The rain has turned the streams flowing to the big lakes into torrents, and the reservoirs themselves are filling with a speed that's almost shocking after several years of drought.

Since March 1, Shasta and Oroville have increased a total of more than 1.5 million acre-feet -- enough water for about 3 million California households for a year.

Storage in Shasta has increased by 874,000 acre-feet; as of Monday morning, the reservoir stands about 105 percent of average for the date -- the first time in more than three years it has risen above its historic norm. The vast lake, which stretches into the upper reaches of the Sacramento, McCloud and Pit rivers, has risen 37 feet in the last two weeks.

The rise has been so dramatic that Shasta is now above its flood limit -- the maximum capacity allowed by federal regulations that require water managers to maintain a certain amount of reservoir space for flood control.

Lake Oroville's storage has increased by 681,000 acre-feet and 60 vertical feet over the past two weeks. By midday Monday, the reservoir had reached 100 percent of average for the date.

Storage in the state's other major reservoirs is also increasing -- though not at the same rate as seen in Shasta and Oroville. A California Department of Water Resources daily report on storage in 46 key reservoirs said Monday that collectively they're now about 78 percent of average for the date. Reservoir levels in the San Joaquin River watershed -- including New Melones, McClure and Pine Flat reservoirs -- are still just one-third to one-half their historic average.

Levels for the state's 10 largest reservoirs at midnight Sunday: