[red-beard]

Originally Posted by jyl

Various watchdog groups tried to get emergency spillway lined with concrete, state and federal agencies and water utilities refused. That spillway is a big earthern ditch with just a concrete lip.

https://www.google.com/amp/www.mercurynews.com/2017/02/12/oroville-dam-feds-and-state-officials-ignored-warnings-12-years-ago/amp/?client=safari

Looks lined with concrete to me.



2007 photo, before concrete



And the damage sure makes it look like there is concrete there. I expect the ground was not properly prepared for the concrete overlay, leading to the damage.