The shore of Shasta Lake behind Shasta Dam in Shasta Lake, Calif., is seen Sunday, March 13, 2016. The lake's water level has been rising after a series of storms brought strong winds, periods of heavy rain, snow and high surf to California Sunday, the fourth straight day of wet weather. The lake is rising after several years of dropping water levels due to the ongoing California drought. (Nathan Solis/The Record Searchlight via AP) (Nathan Solis)

Sunday's storms brought more rain to Northern California, but they also helped the state hit a key milestone in its efforts to recover from the historic four-year drought.

Shasta Lake, the largest reservoir in California and a critical source of water for Central Valley farms and cities from the Bay Area to Bakersfield, reached 100 percent of its historic average Sunday as billions of gallons continued to pour in from drenching downpours.

The 21-mile-long reservoir, north of Redding, holds enough water when full for the needs of 23 million people for a year. Three months ago, on Dec. 8, it was just 29 percent full. On Sunday, it hit 77 percent full -- and 101 percent of the historic average for mid-March -- the first time it has reached that "normal" milestone in three years.

"It's just pouring up here," said Tom Groves, a manager at Shasta Marina at Packers Bay. "The wind is so strong, there are whitecaps and waterfalls all around the lake. A lot of people think it takes years to fill the lake after a drought. But all it needs is one good winter. It will probably be full by May."

Similarly, the state's second-largest reservoir, Oroville in Butte County, reached 69 percent full on Sunday -- 96 percent of its historic average for mid-March. The largest reservoir that serves the 1.4 million customers of the East Bay Municipal Utility District, Pardee, in the Sierra Nevada's Mokelumne watershed, hit 89 percent full -- 103 percent of average.


"This March is wetter than I expected. After February, I was worried," said Jay Lund, director of the Center for Watershed Sciences at UC Davis. "This is really going to help a lot."

Meanwhile, Loch Lomond Reservoir, the largest in Santa Cruz County, also spilled over its dam Sunday, filling to the top for the first time since 2013.

"It's very good news," said Eileen Cross, a spokeswoman for the Santa Cruz Water Department, which serves 93,000 people. "A lot depends on what happens these next few weeks. Based on the supply we have now in the reservoir, that would suggest that we don't need to do restrictions this summer. We'll know by the beginning of April what course of action we'll be taking."

Sunday's storms ended a wet weekend across the Bay Area. Waves in the ocean reached 20 feet, and mountain areas were soaked, with occasional power outages, minor mudslides and downed trees. A sinkhole at Rheem Shopping Center in Moraga caused a gas line break, with no fire, prompting police Sunday to evacuate people within a quarter-mile.

A man walks along the shore of Shasta Lake behind Shasta Dam in Shasta Lake, Calif., Sunday, March 13, 2016. The lake's water level has been rising after a series of storms brought strong winds, periods of heavy rain, snow and high surf to California Sunday, the fourth straight day of wet weather. The lake is rising after several years of dropping water levels due to the ongoing California drought.(Nathan Solis/The Record Searchlight via AP) (Nathan Solis)

Over the 72 hours ending at 4 p.m. Sunday, Mount Diablo received 5.9 inches of rain, Pescadero 7.2, Summit Road on the Santa Cruz-Santa Clara county line 5.7 and Ben Lomond 6.14. Around the bay, totals were more modest: Oakland received 2.53 inches, Walnut Creek 2.12, San Francisco 3.14, San Jose 0.47 and Palo Alto 0.79.

The storms pushed rainfall totals at all of the major cities in Northern California to near 100 percent of the historic average for this date or above, making this winter the best in five years.

What effect that will have on summer water restrictions statewide is still unclear. The State Water Resources Control Board has said it will meet in mid-April to decide how much to relax the mandatory water targets that last summer forced nearly every urban area in the state to impose water rationing and other restrictions.

Experts said Sunday that all the reservoirs are filling, but groundwater levels remain low after four years of heavy pumping during the drought. Some fish species, like endangered salmon, are far from recovery, and the Sierra Nevada snowpack is still only about 83 percent because warm, dry temperatures in February melted large amounts that had built up in January.

"For cities and farmers, this is great news. It's important that the reservoirs are filling," Lund said. "But because we've had an average rain year so far, that doesn't mean the drought is over and we never need to worry about the water supply again."

Lund said, however, that this winter's rains have removed the emergency nature of the drought. He expected there will be some summer restrictions, particularly in Southern California, where rainfall totals have not been as high. However, in Northern California, he said he expects summer drought rules

will be more mild than they were last summer.

Three of the 10 reservoirs in Santa Clara County were spilling Sunday: Vasona, Stevens Creek and Uvas. Because of water levels that rose in Uvas Creek as water poured over the Uvas Dam spillways, more than 150 people were evacuated from Thousand Trails Campground near Morgan Hill after water rose as high as a bridge that is used to cross the creek in the area, authorities said.

There was no major flooding, however.

The Russian River at Guerneville, which emergency officials said might flood this weekend, was expected to crest Monday at 26 feet -- well below its 32-foot flood stage.

At Shasta Lake, the linchpin of the Central Valley Project, a 500-mile-long series of dams and canals that provides the backbone of California's water supply, the changes have been breathtaking.

The water level at the lake has risen 117 feet since Dec. 8, and the reservoir is now holding 3.5 million of its 4.5 million acre-feet capacity. To reach the top of the massive concrete dam, which was built in the 1930s and early 1940s, the water level needs to come up another 38 feet. Since March 1, the lake has risen 32 feet, or 2 feet a day.

This week, however, will see a break in the rain. The National Weather Service said sunny weather will return all week, with another storm system not expected until the middle of the following week.

"Our phone has been ringing off the hook," said Groves at Shasta Marina. "This is going to be a great summer for boating. If it stopped raining today, we'd be extremely happy. Everyone up here is talking about it."

Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN.