Exciting Sunday in Northern California
Posted: Mon Feb 13, 2017 4:07 amSome may have heard, we had a little more excitement in Northern California than we would prefer. This past week the US tallest dam, (at over 900 ft tall), Oroville Dam, about 78 miles north of us, was in the process of letting out some of the huge inflow of run off water from the unprecedented rainfall plus snow melt from a warm storm coming in from the 4000 sq miles of watershed. Suddenly they got reports of chunks of concrete flying up with the heavy water flowing through he spillway, a channel with gates which allows extra water not needed for power to be bled off to avoid overfilling the reservoir. They can theoretically put up to 250,000 cubic feet per second through that channel, though normally its kept much lower as the river canyon is good for up to 200,000 cubic ft per second without overflowing banks. Water was coming from watershed at up to 190,000 CFS at peak! Flow was around 70,000 CFS when concrete broke loose. Flow was immediately shut off ( with of course water still filling dam at 190,000 CFS ). Inspection happened and they saw a crater. Decision was made they still needed to get rid of water to avoid overtopping dam. There's a never used dirt spillway off to the side which over nearly 50 years had grown trees and just was never needed. That was why it was termed auxiliary or emergency spillway. As water crept up past 90% of full through the end of the week, it got dicey. They worked frantically to clear brush to ready the emergency spillway as they cautiously began letting water flow through the damaged spillway's gates. It's not desirable to use the dirt spillway because it has no gates it's a wall where water would just start flowing over. Friday night the water reached 102% full and began cascading over the emergency spillway while they kept an eye on the regular spillway as they let water through while it continued to tear out concrete and earth.
We are sitting here calmly watching TV this afternoon when an emergency broadcast ensues. The emergency spillway wall is undercut by the huge flow and they felt the wall may give way within an hour or so. Evacuations of nearly 200,000 people in the city of Oroville and cities along the path of the Feather River canyon and small towns along the way. As of midnight, the emergency spillway has stopped running as they brought flow through gates of regular spillway up to 100,000 CFS, which they really didn't want to do, but at least the flow is controllable where with emergency spillway it just runs. The emergency is not over, but has eased. At first light they will get a better look with hopefully water down a foot to see what they are up against and began hauling helicopter loads of bags of boulders to drop into the weak spot which was in danger of failure . They are hoping before this weekend storm they can get 50 ft out of the dam to allow for more rain. Our National guard has activated 2100 people to help with aircraft, military police to assist highway patrol in evacuated cities, and help shelter emergency personnel brought in. Highway Patrol has an extra 100 people in place. Cal Fire has activated a crew to assist with air rescue If needed and in taking DWR people over dam to assess. Our department of Emegency Servives are open in the state OES office. Keeping fingers crossed I don't end up with water front property because a big release of water could cause failure of levees all over downstream, ESP bad in places already struggling with flooding. We dodged a bullet for now. I hope our other northern California people check in to let us know they are ok. We are high and dry in Roseville and receiving a few evacuees.
Once we are through this rain season and snow melt is done, usually summer, it will take millions of dollars to repair the two spillways and be ready for the next winter to store and release as needed as it has for nearly half a century.
This dam holds special meaning to me because the spring I was a senior in college, I finally got into the very popular sailing class. We had 16 to 20 ft sailboats we put in Lake Oroville and learned our practical skills. ESP fun for me since the following September I would enter Officer Training and be an Ensign in the Navy! We looked up, way up at the awesome sight of the great 900 ft tall dam towering over us, as it only had a scant 2' years of water in it at that point. Little did I know those days that nearly half century later I would be 78 miles away watching and hoping that great dam, built for flood control and water storage, would be as strong as it looked in 1971.
Cheers all and have a good week.
Velda
We are sitting here calmly watching TV this afternoon when an emergency broadcast ensues. The emergency spillway wall is undercut by the huge flow and they felt the wall may give way within an hour or so. Evacuations of nearly 200,000 people in the city of Oroville and cities along the path of the Feather River canyon and small towns along the way. As of midnight, the emergency spillway has stopped running as they brought flow through gates of regular spillway up to 100,000 CFS, which they really didn't want to do, but at least the flow is controllable where with emergency spillway it just runs. The emergency is not over, but has eased. At first light they will get a better look with hopefully water down a foot to see what they are up against and began hauling helicopter loads of bags of boulders to drop into the weak spot which was in danger of failure . They are hoping before this weekend storm they can get 50 ft out of the dam to allow for more rain. Our National guard has activated 2100 people to help with aircraft, military police to assist highway patrol in evacuated cities, and help shelter emergency personnel brought in. Highway Patrol has an extra 100 people in place. Cal Fire has activated a crew to assist with air rescue If needed and in taking DWR people over dam to assess. Our department of Emegency Servives are open in the state OES office. Keeping fingers crossed I don't end up with water front property because a big release of water could cause failure of levees all over downstream, ESP bad in places already struggling with flooding. We dodged a bullet for now. I hope our other northern California people check in to let us know they are ok. We are high and dry in Roseville and receiving a few evacuees.
Once we are through this rain season and snow melt is done, usually summer, it will take millions of dollars to repair the two spillways and be ready for the next winter to store and release as needed as it has for nearly half a century.
This dam holds special meaning to me because the spring I was a senior in college, I finally got into the very popular sailing class. We had 16 to 20 ft sailboats we put in Lake Oroville and learned our practical skills. ESP fun for me since the following September I would enter Officer Training and be an Ensign in the Navy! We looked up, way up at the awesome sight of the great 900 ft tall dam towering over us, as it only had a scant 2' years of water in it at that point. Little did I know those days that nearly half century later I would be 78 miles away watching and hoping that great dam, built for flood control and water storage, would be as strong as it looked in 1971.
Cheers all and have a good week.
Velda
