UPDATE 3:37 p.m.: Officials at Lake Oroville say they're now working to restart the Hyatt Power Plant near the base of the dam.
The plant has been shut down since last week, when debris from the eroding main spillway washed into the diversion pond, creating a blockage.
Water backed up the channel toward the plant, creating dangerous operating conditions.
Bill Croyle is Acting Director of the Department of Water Resources.
"That plant is important for us to make available," says Croyle. "So, we need to move more of that material out of the way at the bottom of that slope, drop the water level in front of that plant so we can get into normal operation water conditions on the downstream side, and that allows us to add another way to get water out of the reservoir."
Croyle also says it will take a while to remove the debris field.
The flow of water coming down the main spillway was reduced today, in order to give workers more access to the area.
UPDATE 2:30 p.m.: Incident command leaders at Lake Oroville say work crews are making good progress on repairs on the emergency spillway to prevent further erosion.
The next goal is to address an area of debris that's blocking a portion of the diversion pool at the base of the main spillway.
The Department of Water Resources Acting Director Bill Croyle says the conditions at the lake have changed a lot since Sunday and need to be put into perspective.
"The reservoir has been up at much higher than these levels before. You know, we're kind of at normal flood operations here, except for we have a damaged spillway."
Croyle says outflow on the main spillway was reduced Thursday from 100,000 to 80,000 cubic feet per second, and will hold there for the time being.
UPDATE 1 p.m.:
(AP) - California officials are slowing the release of water from a lake behind the nation's tallest dam so crews can remove debris from the bottom of the structure's damaged spillway.
State Department of Water Resources officials said Thursday that removing debris protects Oroville Dam's power plant and will allow for it eventually to be restarted.
Officials had been releasing 100,000 cubic feet of water, or enough to fill an Olympic-size swimming pool, each second from the lake since Sunday, when the sheriff ordered an immediate evacuation. They didn't say how much water is now being released.
Department acting Director Bill Croyle said Wednesday that water managers would start dialing back the flow now that the lake has been reduced and can absorb runoff from storms expected over the next several days.
UPDATE 11 a.m.: The State Department of Water Resources says flows through the Oroville Dam spillway have been reduced to 95,000 cubic feet per second Thursday.
The reduction, from 100,000 cfs, took place so that crews can remove debris from a diversion pool at the bottom of the spillway.
Officials say the outflow will still allow for the reduction of reservoir levels.
Original Post: Nearly 100 workers are part of a 24-hour crew assigned to the emergency Oroville Dam spillway repair project.
Department of Water Resources Acting Director Bill Croyle says those workers are placing 1,200 tons of material in the emergency spillway per hour.
"This community has seen an awful lot of trucks go through, lot of helicopters flying around, and that's an important part of our proactive contingency plans to protect the emergency spillway, should we need to use it again," says Croyle.
Coyle, however, says the likelihood of it being used anytime soon is waning. Water runoff flowing into Lake Oroville has decreased significantly over the past week, and upcoming storm systems do not pose an immediate threat.
-Randol White / Capital Public Radio