Dramatic new images show scale of damage to Oroville Dam spillway

Geologists attempted for the first time Tuesday to figure out what to do about the vast, yawning canyon dug out of the earth after a crater opened up in the Oroville Dam’s concrete spillway and diverted water at high speed into the adjacent hillside.

Monday’s shutoff of water flowing down the main spillway revealed a shocking panorama of damage, forcing experts with the California Department of Water Resources to scramble to figure out how the crippled chute can possibly be fixed by the end of the year — in time for the next rainy season.

“With drones, helicopters, and a team of geologists and other experts, we’re still gathering information about the extent of the erosion on the main spillway,” said Nancy Vogel, a spokeswoman for the California Natural Resources Agency, which oversees the water resources department.

While dumping water downstream, crews discovered a gaping hole in the concrete spillway, forcing them to reduce the flow.

The danger prompted the Feb. 12 evacuation of as many as 188,000 people living in downstream communities.

The ravaged main spillway was dry Monday for the first time in about two weeks, allowing workers to clear out debris below in a bid to get the dam’s hydroelectric plant back up and running, officials said.

Gov. Jerry Brown sent a letter to President Trump last week requesting a waiver that would allow the Oroville spillway repair to happen without review under the National Environmental Policy Act.

The amount of water flowing into the reservoir from the surrounding mountains has decreased to about 22,000 cubic feet per second, down from about 40,000 cubic feet per second on Feb. 13, and it will continue decreasing throughout the week, which is forecast to be mostly dry, officials said.