Following issues with the Oroville Dam's spillway, 13 Action News took a look at Hoover Dam's own spillways.
Both have steel-drum gates that can be operated manually or automatically. They're raised and lowered depending on water levels in the reservoir, along with flood conditions.
They've only been used twice -- once for testing in 1941 and the other because of flooding in 1983.
After the spillways were used both times, engineers found major damage to the concrete linings and underlying rock.
