But the fall-run salmon don't have the same advantages. The San Joaquin's flows often are not as consistent or strong. The water also is warmer. So the fall-run population usually was smaller.

To begin rebuilding the populations, wildlife officials will collect eggs and fingerlings from Northern California streams such as Battle, Deer and Mill creeks, as well as the Feather River. They will be moved to a hatchery just below Friant Dam.

Collecting the fish from several creeks and rivers will help biologists breed strong fish, combining the survival traits fish have developed in their respective streams.

For instance, fish in one stream might be more resilient to warmer water than most salmon. Others might be more resistant to diseases. With wider genetic diversity, the new San Joaquin fish would have a better chance at surviving future changes, which some believe will include climate change.

"We really don't know what the conditions will be or how they will affect flow and water temperatures," said biologist Steve Blumenshine, a Fresno State professor of aquatic ecology.

The restoration target is 30,000 spring-run salmon and 10,000 fall-run salmon each year by the end of 2024. The hatchery's work would be suspended the following year if there are enough salmon, according to the plan.

The new hatchery is planned alongside a state trout hatchery, which has been in operation since the 1950s. The restoration will begin in December 2012 at the state's hatchery where there is enough room for a limited program of salmon breeding until the new hatchery is built. The new hatchery is scheduled for completion in 2014.

Possible money sources include federal funds and the state's 2006 clean water initiative, Proposition 84, but those details have not yet been worked out.