After its third-driest winter on record, driest calendar year and third straight year of below-average precipitation, California water officials were no doubt bracing for bad news when they set out to conduct a statewide snow survey high in the Sierra Nevada Mountain range on April 1. The snow survey is seen as a key marker of the health of the state's water supplies, since it typically marks the peak snow cover for the season.

Snow surveyors found a snowpack on Tuesday that contains just 32% of the average water content typically observed at this time of year, which places 2014 as among the lowest water-content years on record since such records began in 1930.

The low water content, combined with unusually low reservoir levels, means that the country's most populous state faces a long and stressful dry season ahead, with farmers and their thirsty crops competing with urban residents for access to increasingly scarce supplies. The California agriculture industry is the largest of any state in the U.S., generating about $45 billion in annual revenue, and the drought is projected to hit farmers especially hard.

"We're already seeing farmland fallowed and cities scrambling for water supplies," Mark Cowin, director of the California Department of Water Resources, said in a statement. "We can hope that conditions improve, but time is running out, and conservation is the only tool we have against nature's whim."

California has been mired in a historic drought for more than a year, part of a broader multi-year drought that is also affecting other states in the west. It had its warmest and third-driest winter on record, which intensified the preexisting drought following the state's driest calendar year on record in 2013. As of March 25, all of California was in some form of drought condition, with "exceptional drought" gripping about 23% of the state.

The drought is the most severe one-year drought on record in California, even more severe than the 1976-77 drought. To find a comparable drought, you have to go back to events that took place before instrument records began in the late 19th century.

"Snowpack measurement on April 1 is often considered a key measure of where we are," Peter Gleick, president of the Oakland-based environmental-research group Pacific Institute, told reporters on a conference call. “By any measures, our snowpack is low."

Recent storms have helped boost California's water supplies slightly, and forecasts show additional wet weather is possible in parts of the state during the next two weeks. However, precipitation on a scale that would be required to end the drought is not likely until next fall or winter.

Electronic readings from the California Department of Water Resources found that the central parts of the Sierra Nevada have the most snow, with snowpack water content 38% of normal. This compares to 23% of average for the northern mountains and 31% of normal for the south.

Runoff from mountain snowpack contributes about one-third of California's water supply, with the rest coming from reservoirs or piped in from out-of-state. According to the World Resources Institute, a Washington think tank, California draws water from 157 million acres of land across eight states.

Making matters worse, reservoirs are also running far below average levels for this time of year — another sign of the water stress that California will grapple with this summer.

Lake Oroville in Butte County, which is the State Water Project's largest reservoir, is at only 49% of its capacity. And San Luis Reservoir, which contributes water to the State Water Project and the Central Valley Project, is at just 42% of its capacity, the Department of Water Resources said.

Responding to the drought conditions, water suppliers — including the state — have been slashing their promised deliveries. On Jan. 1, the State Water Project, which supplies supplemental water to nearly 25 million Californians and 750,000 acres of irrigated farmland, set its water delivery estimate at zero, which — if it remains at that level — would be the first time that has happened in the 54-year history of the project. In addition, the Department of Water Resources also said it planned to reduce allocations to farmland by 50%, the maximum extent allowable by law.

Santa Clara Valley Water District, which supplies water for much of Silicon Valley, has instituted a mandatory reduction in water use to 20% below 2013 levels, after a series of water-delivery cutbacks from state and federal agencies.

The role of climate change in the current drought is complicated, since natural variability in the climate system has brought more severe and far longer-lasting droughts to the west in the past. However, a new report from the United Nations Intergovernmental Panel on Climate Change and other data show that increased temperatures help dry out soils faster and melt more snow, thereby acting as a drought amplifier.

“We know that climate change is contributing to the current drought,” Pacific Institute's Gleick said. “Climate change now influences extreme events and will continue to do so.”

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