As waterlogged storms repeatedly pounded California this winter, social media was filled with variations on a distinct photo theme. The subject was a freshly plowed road wedged between towering white walls of snow measuring 10 or 20 feet tall. As long as vehicles had safe passage, a wintry trench would be fine — that snow had to go somewhere after all.
But with an early-spring heat wave in the forecast, it’s time to start thinking about what a massive amount of snowmelt will mean for the state — that water has to go somewhere, after all.
Despite snowpack in the Sierra Nevada measuring 153 percent above normal, it should be noted that experts aren’t expecting anything too terrible for California. When the National Weather Service recently issued its spring outlook, minor flooding was foreseen in the Golden State, unlike the deluges seen in the Midwest along the Mississippi and Missouri rivers.
Still, impact is assured from so much water trickling down mountainsides into streams and creeks, eventually joining a river before being captured in a reservoir or flowing all the way to the Pacific Ocean. And that doesn’t take into account the possibility of more storms, such as the one that lashed the Sierra Nevada foothills on Wednesday, dropping up to 30 inches of snow in the higher elevations while prompting the Weather Service to issue warnings for a tornado and flash flooding.
The spillway at Oroville Dam, the United States’ tallest, is about to get tested for the first time since it nearly failed with catastrophic results two years ago. Since the catastrophe, the spillway was rebuilt, and repairs involved more than 1.2 million cubic yards of concrete — enough to fill 372 Olympic-size swimming pools.
According to the Sacramento Bee, “residents downstream of the spillway are watching the spillway nervously. They’ve been skeptical about (California Department of Water Resources’) insistence that small amounts of water flowing down the spillway in recent weeks wasn’t from cracks or other problems. DWR says it’s normal seepage from the spillway gates.”
This inevitable deluge will kick off another inevitability: debates about whether California does enough to capture and store runoff. As the Record of Stockton points out, the state’s last major reservoir project was New Melones on the Stanislaus River in Calaveras County — and it started filling in 1979. “Since then the state has gained about 15 million residents.”
Possible improvements include constructing smaller reservoirs on the eastern side of the Coastal Ranges, generally north of Sacramento, and maybe raising the height of Shasta Dam (at 4.5 million-acre feet the state’s largest reservoir).
In November, the voters of Los Angeles County approved a property tax projected to raise hundreds of millions of dollars annually to capture and clean up storm water.
The coming heat wave, expected to peak on Sunday, is the work of a high-pressure ridge parking over the state. Offshore winds will keep marine air at bay, and high temperatures are expected to soar perhaps a dozen degrees past seasonal norms for the warmest day of 2019 so far.
After the ridge fades, extended forecasts call for unsettled weather across the state — with the possibility of further rain/snow events.