Sierra snowpack at 61% as new drought looms for California this summer

Highlighting the second dry winter in a row, the Sierra Nevada snowpack on Tuesday was just 61% of its historical average for this date, the latest signal that California appears headed toward summer drought conditions, with water restrictions possible in some areas for the first time in five years.

The last major storm system in the state was more than a month ago, when an atmospheric river drenched the Bay Area and Central Coast in late January. Weeks of unusually sunny, dry weather came before it, and have come since. As a result, this winter is shaping up to be similar to 2014, state water officials said Wednesday, a year when California was firmly in the middle of its historic 2012-2016 drought.

"Absent a series of strong storms in March or April we are going to end with a critically dry year on the heels of last year's dry conditions," said Karla Nemeth, director of the state Department of Water Resources. "With back-to-back dry years, water efficiency and drought preparedness are more important than ever."

Water officials across California have watched the dry weather nervously, and have begun to plan for water conservation, and in some cases possible mandatory water restrictions. Many agencies are expected to make their final decisions later this month or in early April.

"All indications are that we are in a drought," said Rick Callender, CEO of the Santa Clara Valley Water District, which provides water to 2 million people in Santa Clara County. "We'll recommend to our board tighter restrictions. I'm not sure yet if they will be mandatory or voluntary."

The East Bay Municipal Utility District, which provides water to 1.4 million people in Alameda and Contra Costa counties, plans to make a decision by late April about whether to impose summer water restrictions, district spokeswoman Andrea Pook said.

Light rain is forecast for this weekend in the Bay Area. A storm system is expected to arrive in the North Bay late Friday afternoon and spread across the region into Saturday. But rainfall amounts will only total about a quarter inch in most Bay Area cities, and about half an inch in the coastal mountains, according to the National Weather Service.

It won't be enough to help the state out of its deep rainfall deficit. Most Bay Area cities and Los Angeles have received about 40% of their normal rainfall totals, and only a month remains in the state's winter rainy season, which typically ends around the beginning of April.

Typically, December, January, February and March are the four wettest months of the year in California.

A year like this one hasn't happened often since California became a state. The seven-month period from July 1 to the end of February has been the seventh driest in San Francisco in the past 172 years, since 1849, when records began. And over the same time, the Northern Sierra Nevada, which is key to the state's water supply, is suffering through it sixth driest season, according to calculations from Jan Null, a meteorologist with Golden Gate Weather Services in Half Moon Bay.

How much snow falls every winter is critical to California's water picture. The snow, which forms a vast "frozen reservoir" over California's 400-mile-long Sierra mountain range, provides nearly one-third of the state's water supply for cities and farms as it slowly melts in the spring and summer months. The melt sends billions of gallons of clean, fresh water flowing down dozens of rivers and streams into reservoirs.

After a dry year last year, which did little to replenish them, most of the state's largest reservoirs are currently below historical averages for this time of year.

Shasta Lake, the state's largest reservoir, near Redding, is currently 50% full, or 68% of normal for this time of year. Lake Oroville, in Butte County, is 38% full, or 55% of normal. New Melones Lake, in the Sierra Foothills of Calaveras and Tuolumne counties, is in better shape, at 65% full, or 106% of its historic average. And San Luis Reservoir, near Los Banos, is 58% full, or 68% of its historical average.

According to the U.S. Drought Monitor, a weekly federal report, 84% of California is in at least a "moderate drought," while 29% is in a "severe drought," including Napa, Solano, Inyo and San Bernardino counties, along with much of the Sacramento Valley.

About 84% of California was in a "moderate drought" or worse, with 29% in a "severe drought," according to the U.S. Drought Monitor on Feb. 27, 2020.

If the dry weather persists in March and April, fire danger will be heightened this summer and fall because moisture levels in grasses, shrubs and trees will be low. Add to that, temperatures are rising due to climate change. Last year was the hottest year recorded on Earth since 1880 when modern temperature records began, according to NASA and NOAA, the parent agency of the National Weather Service. The seven hottest years since 1880 have all occurred in the past seven years.

Each community in the state has different water supply conditions. Some areas have large amounts of water stored in underground aquifers, if the geology near them is favorable, while others do not. Other places have more reservoirs, or recycled water projects, or in the case of San Diego and Santa Barbara, new ocean desalination plants built in recent years.

One thing that is a near certainty for nearly every California community, starting in April or May: There will be a new push by city water departments and regional water districts to ask people to use less water on landscaping, take shorter showers and check homes for leaks. In some cases, those requests will be public relations campaigns. In others, they will come with financial penalties for water use over certain levels, as happened during the 2012-16 drought in many areas.

"It's safe to say we will end this year dry," said Sean DeGuzman, chief of the state Department of Water Resources Snow Surveys and Water Supply Forecasting Section. "It's important that we'll have to plan accordingly."