Here's some background on the Oroville Dam. The
height of the dam itself is 742', one of the highest if not the highest earthen dams in the country. It was
built in 1968 and first filled the next year. It has a capacity of 3,537,577 acre feet of water. The maximum fill level is 901 feet above sea level, same as the entrance to the emergency spillway.
Here's some
current info:
Current height of the water is 887', just 14' below the emergency spillway, and up 7' since 7 AM today, 12 hours ago. Current inflow is 189,579 CFS, outflow 42,375 CFS. If inflow and outflow stay the same as it is right now, water will reach the emergency spillway by this time tomorrow. Keep in mind that the V shape of the canyon means that every additional foot of water rise requires proportionally more water to achieve, and the inflow rate seems to be dropping as the rain lets up. But without increased outflow rate, even two days before reaching the emergency spillway is optimistic. Crews have been clearing brush and trees below the emergency spillway since last night in an effort to keep debris out of the Feather River and Thermalito Forebay.
The dam authority tested the main spillway yesterday afternoon at 15,000 CFS in an effort to asses what damage would occur through continued use. More of the spillway crumbled, but it has been determined that any additional damage will not compromise the integrity of the dam. One local expert estimates that most of the spillway will be destroyed, so it's a good thing California has money growing out of its ears. The construction jobs next summer will be good for the local economy. I've forwarded Eric's contact info to the Dam folks in case they need a siphon consultant.:laughing:
The best coverage is coming out of Redding TV station
KRCR.
Latest reports are that the hole had doubled in size from yesterday's 185' x 250' and 45' deep. KRCR is also reporting that earlier today, mandatory evacuations were ordered along the Upper Sacramento River in Northern Shasta County and Southern Siskiyou County. This included areas in the towns of Castella, Sweetbriar and Dunsmuir. The evacuation orders were lifted at 6PM as water levels started to drop.
[video]http://www.veoh.com/watch/v117613376GWdHfKkE[/video]
For my part, I don't think I've ever seen so much water coming over the falls across the side canyon to the north of here. I can hear the water anywhere inside the house, and it's pretty loud outside.
It's a good thing I I cancelled my trip to town as we've picked up more than 2.5" of rain since midnight. I'm not worrying about flooding here, as the property is 200' above the top of the dam/reservoir. But I noticed that the article Eric cited yesterday mentioned a 1975 earthquake just south of Oroville Dam. When I looked into seismic activity in this area prior to buying the property, I found that scientists think the quake was caused when large water releases that summer let the earth under the reservoir spring back when the water weight was removed. Apparently there have been enough fill and drain cycles since then that no further quakes have occurred. Apparently the insurance companies are also aware of this, and earthquake insurance would have been only a quarter of what I used to pay in the San Francisco Bay Area. I decided not to buy it for this place since the house is built on solid rock over a concrete slab foundation.
Anyway, the biggest part of the rain seems to have passed, with maybe another half inch due before things dry up tomorrow night. Forecasts call for some sunny days starting Saturday, but by Wednesday night we'll be in for more, perhaps as much as an inch per day through the weekend. That's not much time for a fix, and my guess is they'll instead choose to keep drawing down the reservoir in hopes of managing possible floods from the coming rain.
Oh, and it was announced today that the all knowing Poobahs in Sacramento have decided to leave the drought inspired water conversation rules in place for the summer. Perhaps they haven't had enough flooding downtown yet to get their attention?:confused2:
:thumbdown:
