Mar 22, 2016 1:54 PM by Cecile Juliette
"Lake Oroville is currently at elevation 854 feet, which is 46 feet from the top," says Kevin Dossey, Senior Engineer with the Department of Water Resources, "It's come up more than 204 feet since the low point in December...so it's really been coming up fast."
Engineers could begin releasing water from the Lake Oroville Dam soon. Says Dossey, "The snow levels have been pretty high, so these big storms, while they're producing snow in the upper elevations, they're also producing a lot of runoff directly into the lake from the basin."
The California Department of Water Resources is keeping a close eye on the 48 year-old dam. Recent rains have caused the lake level to spike, and engineers want to maintain a certain amount of reserve space. El Nino has brought the North State a series of drenching storms in recent months. Dossey says, in a normal year, depending on the wetness index, the Army Corps of Engineers flood control criteria dictates that dam operators increase releases if the lake rises to between 848-1/2 and 875 feet before April 1. The lake has already encroached into the low end of the spectrum by 5 1/2 feet, with more than a week left in the month.
The Department of Water Resources and the Army Corps of Engineers met Monday to discuss whether to allow the lake to continue to rise. Says Dossey, "The lake has come up 80 feet in the last 16 days, which is a phenomenal rate of increase. That's why we're negotiating with the Army Corps to get them to relax the standards, so we can store as much water as possible."
Engineers could begin releasing water from the dam soon. Says Dossey, "The snow levels have been pretty high, so these big storms, while they're producing snow in the upper elevations, they're also producing a lot of runoff directly into the lake from the basin."
Dossey says monitoring the lake level is a balancing act. He says, "We're trying our best to store as much as we can, but flood control is very important...the dam design flood is a 450 year flood. We can operate if we're at this flood reservation capacity. If a big Pineapple Express is coming in, we could open the controlled spillway gates to a maximum of 150,000 CFS (cubic feet per second) and control that surge of water into the lake, so it wouldn't spill over top of the emergency spillway. If it's a more intense storm, with a higher return period, like a 1,000 year storm, it would be possible that the lake could surge up and spill over the emergency spillway gates, and we'd have levees over-topping. We'd flood Oroville and Gridley, Live Oak, and Yuba City. We need to maintain that flood control reservation, so that we don't overtop downstream levee capacity."
"The flood control criteria allows us to operate, depending on the wetness index, to an elevation of between about 850 and about 875 prior to April 1, depending on how dry it is. It's currently pretty wet, so the index would indicate we need to keep it below 848-1/2 to be exact. But we're negotiating with the Army Corps of Engineers because a dry spell is coming up, we may be allowed to encroach a little more, and let the lake come on up."
California has experienced drought conditions since 2012. While it has been dry in recent years, the El Nino Winter brought much-needed relief to the North State. According to the Department of Water Resources, the lake is predicted to rise to 892 feet by mid-June, bringing it to within 8 feet of capacity, which is 900 feet. Dossey says the last time water was released through the spillway from the Lake Oroville was in 2011. He says if high releases are required for flood control purposes this Spring, DWR will likely release water through both the spillway and the Hyatt Powerplant.