The main spillway is out of action due to major erosion damage in its concrete flume. The power plant is shut down because the water level at the low end, in the diversion pool, is too high. So the two normal ways of releasing water are out of service. The emergency spillway is just a dirt hill near the dam with a concrete lip at the top.
There's a data feed from sensors at the dam.[1] "Level" is probably good data. "Out" flow rate may not be meaningful; the emergency spillway probably lacks a flow meter. Here's a plot of "Level".[2] When it's below 900, the auxiliary spillway should stop flowing. As of 2330, it's at 900 feet almost exactly.
The main spillway was open last night, carrying 100,000 cu ft/s of water (comparable to Niagara Falls). I guess it is still open, but I only spent a minute trying to find a current source.
They had reduced the main spillway flow prior to water starting to flow out the emergency spillway, but they increased it after that happened.
edit: it seems that the water level is below the emergency spillway now, but the main spillway is still open, probably at least partly out of concern about coming rain.
The video clearly shows the over-topping of the emergency spillway and the flooding/over-topping of the recreational area.
It also shows the main spillway and the damage is obvious, particularly at the 22 minute mark.
It's actually surprising how bad the damage is to the main spillway, it's not just a 'sink-hole' as was earlier described, it appears totally destroyed across a large portion of the middle part causing severe erosion of the land underneath and water spilling to the left side as well as rebounding up and over to the remaining lower section.
This video shows the damage to the main spillway even more clearly:
Currently there are 100,000 cfs flowing down the main spillway. That's how they dropped the level of the Lake so quickly. But, you are correct that the main spillway is heavily damaged, but they are still using it because they don't have another choice and there is more rain on the way.
no, they only close it for short periods of time during visual inspection of the damage, the electric part is completely out of service, the spillways are the only drains currently.
edit: it should be noted that the main spillway damage in itself doesn't threaten the hill and the lake, the issue is fragments or rocks and concrete sent downstream, that might partially clog the river or destroy some infrastructure.
There's a data feed from sensors at the dam.[1] "Level" is probably good data. "Out" flow rate may not be meaningful; the emergency spillway probably lacks a flow meter. Here's a plot of "Level".[2] When it's below 900, the auxiliary spillway should stop flowing. As of 2330, it's at 900 feet almost exactly.
[1] http://rdcfeeds.redding.com/lakelevels/oro.cfm [2] http://cdec.water.ca.gov/jspplot/jspPlotServlet.jsp?sensor_n...