OROVILLE (KTVU) -- The Oroville Dam rehabilitation project moved into a critical phase Monday as warmer weather raised the risk of an enormous amount of water being released into the dam as the snowpack melts.
The water from the Oroville Dam's regular spillway was reduced to virtually nothing but officials say they don't know how much water can be transported down the already damaged main spillway without further damage occurring.
The re-fortification of the emergency spillway at the top of the dam is nearly complete but officials must also begin removing the huge debris pile at the foot of the spillway. That could take between five and seven days, officials say.
The work will allow the dam's hydro-electric plant, which is currently blocked off by that debris, to resume operating.
The power plant is also critical in keeping the reservoir level safe. And, as the hydropower plant uses water to turn the generators, it can also release enough water down the Feather River to protect fish habitats.
Until then, fish rescue crews will gather up and preserve stranded fish populations from various pools on the River until flows return to normal, which could occur next week.
We want to "minimize the threat to the levee system, our environment (and) our fish resources as we move through this period," said Bill Croyle, acting director of the California Department of Water Resources.
Finally, officials want to assure that reservoir level goes no higher than 850 feet, a task that has been achieved.
But Butte County Sheriff Kory Honea said until that work is completed, "Our evacuation warning is still in effect."
Officials may have to scramble because March's warmer weather will thaw the gigantic snow pack.
The melting snow will send a lot of water into the reservoir; some of which may have to go over the damaged spillway before final repairs can be made.
To assess the actual damage to the spillway state water officials are using drones and helicopters. Privately-owned drones are forbidden by state law until mid-May.
"If we have to shut down because of a third-party drone that's in our airspace that affects the public safety of our first responders, as well as the community of Oroville," Croyle said.
By KTVU reporter Tom Vacar.