When the 770-ft-tall Oroville Dam, the tallest in the U.S., was completed in 1968, it was equipped with a 3,055-ft-long main spillway—and an emergency spillway that had never been used. That changed in February 2017 when weeks of heavy rain filled the reservoir to capacity, causing the California Dept. of Water Resources (DWR) to ramp up water releases from the main spillway.
But the heavy flows eroded a large chunk of the spillway concrete, forcing officials to hold back water while they assessed the damage.
