Rain storms this winter have swelled water in Lake Sonoma to near-record levels, submerging once-dry boat ramps, repeatedly flooding the dockside marina and banishing the bath tub rings that for years were a telltale sign of the state’s prolonged and withering drought.
Only in the El Niño winter of 1995 did the reservoir in northwestern Sonoma County — the North Bay’s largest, created behind Warm Springs Dam in 1982 — rise higher than it did early this week, when it topped 125 percent of its capacity, with enough water to cover 300,000 football fields 1-foot-deep. The bountiful supply is more than twice the volume of water held in the lake in November 2014, amid the five-year drought that forced conservation of drinking water and cut into recreational opportunities for boaters and others.
The outlook now could hardly be more different.
With torrents of runoff coming into Lake Sonoma and Lake Mendocino, the Russian River’s smaller reservoir to the north, dam managers are now cranking up their releases to preserve room for additional storms. Another front is expected to arrive Wednesday night.
“We’re releasing a lot of water like we’re supposed to — we need to keep space open for the next big storm,” said Mike Dillabough, chief of Operations and Readiness division for the United States Army Corps of Engineers’ San Francisco Division. “But we’re told it’s burgeoning on a record year.”
Water levels in Lake Mendocino reached 117 percent of seasonal capacity Tuesday, with nearly three times the water volume from its two-decade low in November 2015.
The wet winter is a boon for boaters and wildlife. During the parched summers of 2013-15, boats launched from trailers into Lake Sonoma had a long way to travel down the ramp before they reached the water, said Brittany Wagner, office manager for Lake Sonoma Resort Area. This summer, the trip should be much shorter.
“These storms will make for a good summer,” Wagner said. “There were a few years where there wasn’t a whole lot of water in the lake.”
With the lake level up 18 feet since Oct. 1, the dockside marina at Lake Sonoma Resort is underwater for the fourth time this year. Wagner said flooding of the store didn’t amount to a disaster because the building is designed to withstand rising waters from time to time.
For the region, flooding and landslides caused by heavy rains have created burdens, such as closing roads, triggering mudslides and inundating homes.
“We asked for a wet winter and that’s what we’re getting, but sometimes you have to be careful what you wished for,” said Brad Sherwood, spokesman for the Sonoma County Water Agency.
Still, with Lake Sonoma and Lake Mendocino full, the system that serves 600,000 North Bay customers will have plentiful supplies come this dry season, the first time water managers will have such a bright long-term outlook in many years. Officially, the North Bay exited drought status late last year.
In such wet years, plenty of water is around to meet both human demands and the needs of fisheries and watersheds, Sherwood said. High water levels in the fall are good for coho and Chinook salmon at the Warm Springs Fish hatchery at Lake Sonoma, he said.