California Threats Jump from Fires to Floods as Wet Season Hits

By Brian K. Sullivan | December 10, 2019

California’s climate threats could soon be jumping from wildfires and blackouts to floods and mudslides as the wet season kicks into gear.

About half the water that falls in the state in any given year does so in the 90 days between Dec. 1 and the end of February. Too much rain has at times meant catastrophic floods and dangerous mudslides. Too little threatens agriculture with drought, and potentially creates a tinderbox effect in the year ahead.

Meanwhile, a late start to the wet season has firefighters remaining on watch. While last week saw rains across the state, the next 7 days are forecast to be dry, with a high pressure system sitting over the west.

“California has always been a land of extremes, it has just got a lot worse in recent years,” said Peter Gleick, co-founder of the Pacific Institute, a non-profit that studies climate issues. “We seem to segue right from fire season into either drought or flood, with nothing in between.”

While PG&E Corp. declared in November that the end of the fire season was near, consider the following. The Thomas Fire, the second-largest in the state’s history, hit on Dec. 4, 2017, eventually burning 281,893 acres before it was contained on Jan. 12 after torrential rains fell. But those rains brought flooding and mudslides to the community of Montecito, killing 23 people.

The state’s reservoir system is gearing up for this year’s wet season with plans to control area flooding with planned releases when needed, while keeping as much water as possible on hand to meet drinking, agriculture and industrial needs for the rest of the year. At the same time, the National Weather Service and the state are monitoring the snow pack on the Sierra Nevada Mountains to weigh their potential effect on California’s streams and rivers.

Now the levels are deep, banking water that will be needed to bring moisture to the state once the wet season is over. But one warm spell in the meantime can make a big difference, said Graham Fogg, professor of hydrology at University of California at Davis.

Warm winter storms can “release a whole lot of water,” Fogg said in a telephone interview. “And that’s where we get the flood hazards downstream, especially in the Central Valley and coastal basins.” Meanwhile, early release from the snow pack means less water available when summer hits, raising drought risks.

California is no stranger to that threat, suffering through one of its worst droughts in modern history from 2011 to 2017.

“Predicting whether, in the next decade, we are in for another five-year drought or ten-year drought or 20-year drought that’s a big unknown,” Fogg said by telephone.

By recent standards, this year’s fire season inflicted relatively little damage. California’s Department of Forestry & Fire Protection recorded 6,872 blazes, scorching 253,321 acres, burning 732 buildings and leading to three deaths. As sobering as those number sound, they pale compared to the nearly 2 million acres burned and 100 people killed in 2018.

This year, however, the state resorted to a desperate tactic to prevent fires, as utilities repeatedly cut power to millions of Californians so live wires wouldn’t generate sparks during wind storms. The intentional blackouts, once limited to small outages in rural areas, struck suburbs and portions of such densely populated cities as Oakland.

In December, Cal Fire reported 212 small fires, and on Monday let go the last of about 2,600 seasonal firefighters that helped battle almost 7,000 fires this year, according to Scott McLean, a department spokesman.

While the fire season “is diminished, it is not yet gone,” McLean said by phone. “We’re watching the weather as always.”

While the state’s fire monitor has let go its seasonal firefighters, it remains prepared with 13 new engines to join a fleet that’s staffed year round, McLean said.

Climate change has made a mark on California’s water cycle, Fogg said. But research is underway looking at how best to deal with storms that bring more rain than snow. One potential solution is to capture the water flowing out of the mountains, and use it to recharge aquifers in the central and southern part of the state.

“It is a constant challenge to balance these extreme events and it is going to get worse,” the Pacific Institute’s Gleick said.

–With assistance from David R. Baker.

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