[Paladin2]

At some points in time, over the years, when the reservoir was high enough, the spillway could have been tested at its rated flow at least for a few minutes.

When the Hoover Dam was finished the reservoir was filled to test the bypass pipes/tunnels. That left a lighter colored rock ring around the reservoir even decades later.

I don't know if the controlled spillway at Oro was ever proof tested.

[lacrew]

Good point. They could have tested the spillway. I tried to look back and find flow data for the Feather River, that would give an indication of what their highest release has ever been...but could find nothing.

I did find a link to the last 7 days release from the lake.

http://cdec.water.ca.gov/cgi-progs/queryRES?ORO