No doubt — it’s been a great month for California.
A more favorable, wet El Niño pattern has finally kicked in after a pathetically dry February. Across the northern half of the state, major cities including San Francisco and Sacramento have already seen more rain in the first 10 days of March than they normally do in the entire month.
But it hasn’t been nearly enough to put an end to the state’s exceptional drought, which will likely continue into next winter.
Despite widespread rainfall totals of three to six inches across central and northern California since March 1, there was no change in the drought update released Thursday by the U.S. Drought Monitor. Southern California actually saw conditions worsen in the first week of March.
This winter’s very strong El Niño, which has led to a rainy boom in years past, has been a huge disappointment for Southern California. “February is normally one of the wettest months of the year, especially in Southern California,” said NOAA senior meteorologist David Miskus, “and it was quite dry.”
Miskus, who authored Thursday’s update, said that the California-Nevada drought team concluded that heavy rain during the first week of March “made up” for the previous three warm and dry weeks in the northern half of the state. The team considered some degradation, he added, but they saw the rain in the weekend forecast and held off.
Unfortunately, while the March storms have brought ample rainfall, they’ve been too warm to deliver the kind of snow Miskus likes to see on the Sierra Mountains — an important factor in drought mitigation. Snow pack serves as secondary reservoirs for the state, holding water until the spring months when it melts and replenishes lakes.
As another series of storms thrashes the state with heavy rain and snow, Californians are optimistic that March will be the miracle they’ve hoped for. Reservoirs have shown marked improvement since earlier this winter.
Lake Shasta in far northern California is at nearly 70 percent capacity after rising 100 feet since early December. Folsom Lake, which has been used as a poster child in the media for the severity of the drought, was up to 69 percent capacity as of Friday — 19 percent higher than its historical average level.
— NWS Sacramento (@NWSSacramento) March 9, 2016
With rain in the forecast, dams have been releasing reservoir water, which has led people to believe the drought is coming to an end. Miskus cautions this is not any kind of an indicator of drought conditions in the state.
“They can’t hoard it all,” Miskus said. “They have to [release water] downstream for wildlife, drinking water and agriculture. Just because they release it doesn’t mean the drought is over. People don’t understand that.”
Also at play is a decades-old rule that requires reservoirs to release water when they’re well-below capacity — even in the midst of exceptional drought — to prevent flooding in the event of a major winter storm.
At Folsom Lake, billions of gallons of water have been sent downstream, much of which ended up in San Francisco Bay, KQED’s Lauren Sommer reported in late February. “Sitting 40 percent empty allows the reservoir to act as a buffer against floods, gulping the runoff without overflowing,” Sommer reported. “In years where the upstream reservoirs are fuller, Folsom Reservoir is required to remain 60 percent empty.”
The flood gates were opened ahead of March storms, which will continue to inundate much of the state through the weekend. “I’m looking at the radar right now and they’re just getting hammered up there,” said Miskus on Friday. “I would be very surprised if those areas don’t see a one-category improvement next week.”
A one-category improvement in northern and central California would be phenomenal, but the state has such a long way to go before it can say drought conditions have significantly improved. Miskus says they need much more than a couple of weeks of above-average rain.
“We need another winter or two like this — that would go a long way to improving the drought conditions,” Miskus said. “Everything counts on this winter precip, and if they don’t get it they’re screwed until next winter.”