The Department of Water Resources hopes to have them ready to use, if needed, by Nov. 1.
VIDEO: Controlled explosions at Oroville Dam pave the way for next phase of rebuilding
The main spillway split during a major rainstorm in February of last year.
More than 180,000 residents were then evacuated, over fears the emergency spillway would fail.
For more stories, photos, and video on Oroville Dam, visit this page.