The California Department of Water Resources said work on the Lake Oroville Spillway has reached a milestone.
The project's independent Board of Consultants approved design plans for the soon-to-be-built structure.
The Department also announced Wednesday the spillway is shut down for the summer, and will not open again until needed during the next rainy season.
DWR's David Gutierrez said rain in Thursday's forecast won't present a problem.
"We fully anticipate that the reservoir and the powerhouse that we're actually using to keep the lake at the right level, this particular storm will not be an issue at all for the reservoir or the safety of the dam," Gutierrez said.
Blasting and excavation on the lower portion of the main spillway is ahead of schedule. That portion is expected to be rebuilt prior to November 1.