The Oroville Dam has gotten a run of near ideal weather, with only 0.16 inches of rain since February 22, and virtually no precipitation expected for the next week. (Although the warm, sunny weather will likely melt some snow.) They’re now running over 8k cubic feet of water per second through the powerplant (about 60% of its capacity), almost as much as is currently pouring into the reservoir due to the long dry spell.
The reservoir is a few inches below the 860 foot level that was designated as the point at which they’d turn back on the main spillway. But now they’ve decided to let the lake rise to 865 feet (36′ below the dangerous Emergency Spillway overflows) before restarting the main spillway, which might allow them to continue dredging the river at the foot of the spillway thru the end of the next work week before they’d have to clear away the heavy equipment and unleash the spillway torrent again.
Hopefully they’ll dredge enough debris out of the riverbed next week to run the powerplant at full capacity, because the powerplant method of draining the reservoir doesn’t cause problems (knock on wood). Whereas the harder they have to run the main spillway, the more debris winds up in the riverbed, forming another impromptu dam that shuts down the powerplant. (The Sisyphus Syndrome.)
Here’s what happens to the river when they run the broken main spillway at two-thirds of rated capacity:
They’re also trying to harden some parts of the exposed mountain side where the broken main spillway has been eroding down into the river.
They’re still highly vulnerable to a major pineapple express warm rainstorm dumping a lot of rain and melting asnow, but without some major bad luck on the weather front, the path for getting out of this winter now looks pretty doable.
No plans have been announced yet for a long term fix for the broken spillway.