Advertisement Day 3 of Oroville spillway damage: Where does it stand? DWR, engineers assess, discuss possible solutions after erosion Share Shares Copy Link Copy

Thursday marks the third day of engineers and water officials assessing damage and a possible solution for the continued erosion at the Oroville Dam Spillway, but a constant onslaught of rain isn't helping the situation at the lake or the spillway.The hole, which was initially believed to be 180 feet wide by 250 feet long by 45 feet deep, has gotten significantly bigger since it was first noticed Tuesday morning, in part because of the increase in outflow from the lake, according to the California Department of Water Resources.Inflows into the lake are more than 118,000 cubic feet per second (cfs). Compare that to about 35,000 cfs that is being let out of Lake Oroville, DWR officials said. In addition, 13,000 cfs was being let out of the Hyatt Power Plant.Get a bird's eye view of the Oroville Dam Spillway erosionThe release of water through the spillway will likely continue to cause more damage at the eroded hole, which is about two-thirds down the spillway chute. Crews have set up booms and other devices to catch debris that might flow down into the Feather River.Engineers and DWR officials are monitoring the spillway 24 hours a day by way or cameras, drones and other technology, as well as people who are out at the chute throughout the day and night, DWR spokesperson Eric See said.The spillway has a maximum capacity of 250,000 cfs, but the most that has ever flowed down the chute was about 150,000 cfs in 1997.As of noon Thursday, Lake Oroville stood at 90 percent of capacity -- 6.5 percent higher than it was Wednesday afternoon -- as water is still being dumped into the reservoir, while a significantly less amount is being let out.As the lake continues to rise, officials are preparing for the possibility of using the ungated emergency spillway just to the north of the primary spillway, which would release water into uncontrolled land in the valley and the Feather River.The emergency spillway can be used only once the lake gets to 100 percent capacity or 901 feet in elevation. The reservoir holds 3.5 million acre-feet, but as of noon Thursday, What will it take to repair the Oroville Dam Spillway?Crews are working Thursday to clear out trees and brush below the emergency spillway in case that would need to be used, which would prevent extra debris from flowing into the river.It would be the first time the spillway has been used in the dam's 48-year history, although the reservoir came within a foot of overflowing into this spillway in January 1997.See said Thursday that officials are still not sure what caused the erosion, but added that there was no indication of a problem when the spillway was used earlier in the year.The Oroville Dam is not damaged and is "in no way being jeopardized by the (eroding spillway)," See said.Water officials began letting 55,000 cfs of water out of Lake Oroville on Tuesday morning, but soon after, people began noticing a large hole in the dam spillway, prompting water releases to be almost completely halted.The DWR conducted a test of the spillway Wednesday afternoon, in which they let out about 20,000 cfs for several hours. That led to further erosion and chunks of concrete that went tumbling down into the Feather River below.Parts of the right-side wall were lost, and the hole in the middle of the spillway got bigger, DWR officials said Wednesday.