California is drying up, and not just in the southern half that was previously thought to be the most parched.
On Thursday, more of the state than ever before -- including much of Northern California and nearly all of the Bay Area -- reached the most severe drought classification given by a federal monitoring system. And if the trend continues, water reserves could be tapped by next summer.
"This is unprecedented," said Mark Strudley, a hydrologist with the National Weather Service. "Fifty-eight percent of the state is in D4, and that's not yet happened since the drought monitor started [in 1999]."
The U.S. Drought Monitor has five categories to label the intensity of a drought, ranging from D0, or abnormally dry, to D4, considered an exceptional drought. Various factors contribute to drought intensity, including temperatures, precipitation, groundwater levels and how many water districts are running low on water.
An additional 22 percent of California, including for the first time Napa and Sonoma counties, reached the most severe drought level Thursday, which is further evidence that California might not have enough water by next summer.
"If we have another year that's similar in style, it looks like what might be possible is a lot of those reserves that are allowing systems to subsist through this year ... would be all used up," Strudley explained. "Then we wouldn't have much, if anything, to get through next summer."
The historical average summer drawdown of California's 154 reservoirs totals 8.2 million acre-feet, but usage in 2012 and 2013, the first two years of the drought, averaged 11.5 million acre-feet.
Storage has fallen to 17.3 million acre-feet, meaning California is short about 11.6 million acre-feet -- more than a year's worth of reservoir water -- for this time of year.
The worst-case scenario would see some of California's biggest reservoirs drying up -- an outcome that could potentially lead to lowering environmental regulations and forcing the state to haul in water from another source, according to Strudley.
"That's the most-dire picture," he said. "It's not outside the realm of possibility."
San Francisco has been in D4 status since April 24. This year marks the 15th-driest rain year for The City since the National Weather Service began measuring San Francisco's rainfall in 1849, according to Strudley.
There have been just 42 days with measurable rain in The City so far this year. Only four other years since 1849 had fewer days of rainfall, Strudley said.
Additionally, this is the fourth-driest period of three consecutive years for San Francisco, after 1974-77, 1958-61 and 1897-1900 (rain years are July 1 to June 30).
The City, however, appears to be doing its part for water conservation. Water customers in San Francisco and surrounding areas served by the San Francisco Public Utilities Commission have cut their water use by 10 percent, as asked by city officials in January.
As of Wednesday, SFPUC water customers have saved about 3.5 billion gallons of the approximately 8 billion gallons of water needed by the end of the year, commission spokesman Charles Sheehan said.
"We've made tremendous progress this summer to catch up to our conservation goals," Sheehan said. "We're starting to see real results."
New statewide regulations that include fines of up to $500 a day for residents who waste water took effect Tuesday.
Though California is in the third year of its severe drought, this year marked the first time any part of the state reached D4 classification since the U.S. Drought Monitor's inception, Strudley said.
It remains to be seen whether enough rain will fall this year to replenish depleting reservoirs.
"The stuff that's pushing us through this summer in the reservoirs will basically not be there if we don't get normal rainfall," Strudley said. "If we get another drought year, we're not going to have this cushion to push us through next summer."
And what happens if California actually runs out of water?
"When the water really runs out, I don't think a lot of people know what's exactly going to happen," Strudley said.