With summer approaching state water managers say California's snowpack is at 18 percent of average for the date.
The Department of Water Resources on Thursday said the season's final survey of the Sierra Nevada snowpack found more bare ground than snow.
The Sierra snowpack is an essential element of California's water supply — it accounts for about one-third of the state's water.
The last measurement was on April 1, considered the peak of the snow season. It showed that the state's snowpack was about 32 percent of average water content.
Tyrone Jue, the spokesperson for the SFPUC, said that snowpack for the Hetch Hetchy watershed, from which San Francisco gets its water, was at 38 percent of normal levels as of April 1.
DWR Director Mark Cowin says the dire results reaffirm that every drop of water in the state needs to be saved.
Jue echoed Cowin's warning, asking San Franciscans to conserve as much water as possible. “We need everyone to do their part this summer to reduce water use,” Jue said. SFPUC has asked its 2.6 million water users to cut consumption by 10 percent.
“We have the possibility to take more stringent actions if the voluntary call is not sufficient,” Jue added. If water is not conserved, the SFPUC has the option to instate mandatory water rationing for the Bay Area.
“Conservation is going to be a key way for us to stretch our water supplies,” Jue said.
California suffered its last major drought in 2007. That year, the April 1 measurement showed snowpack at approximately 50 percent of normal levels.
A chart provided by SFPUC shows snowpack levels for the Hetch Hetchy watershed in 2007, 2013, and 2014, as well as the median snowpack levels.
Although mandatory water rationing is not yet on the horizon for San Francisco, it may become a reality in other parts of the state. State water managers are set to order farmers and other big water users to limit the water they take from rivers for the first time since 1977.
The State Water Resources Control Board projected that curtailment letters would be sent out later this month for water users on 10 different rivers and their watersheds.
While no letters have yet been sent, the prospect is extremely likely, water officials said.
The orders will be delivered first to junior water-rights holders — those who obtained their water rights after 1914 and whose ability to take water is second behind pre-1914 senior rights holders. Senior holders would still be able to take water initially, and only be ordered to curtail if conditions became even more extreme.
The rare measure of ordering curtailments comes amid the third year of withering drought conditions.
The Associated Press contributed to this report.