The project to get Lake Oroville's damaged spillway functional by November 1 is moving into its heavy-construction phase.
The focus over the next five months will be on the damaged portion of the main spillway.
This is when construction crews will remove, rebuild, and repair much of the structure.
Erin Mellon with the California Natural Resources Agency says the concrete near the top is still in pretty good shape, so most of the work will be below that.
The goal for phase one of the project is to have a functional spillway in place by the start of the rainy season.
"And then, come 2018, that upper portion of the spillway - it's about another thousand feet of concrete - will be pulled out and replaced as well," says Mellon.
Phase two includes upgrading the spillway gates to handle higher water flows.
Crews are also expected to begin work on the emergency spillway next year.
The Department of Water Resources says nearly all of the recreational facilities at Lake Oroville will remain open during the construction period.
However, some trails near the spillway and the adjacent boat launch are closed.
You can see live webcams of the spillway construction here.