VOL . 44 • ISS . 1

The Mokelumne River only contributes 3 percent of the total water going into the Sacramento-San Joaquin River Delta , but it has produced up 51 percent of the salmon caught by commercial fishermen on the ocean when the season has been open .

Photo by Dan Bacher

LEMENTS , CA — A record high number of fall-run Chinook salmon returned to the California ’ s Mokelumne River in 2024 . while an alarmingly low number of Chinooks have come back to the Upper Sacramento River ’ s Coleman National Fish Hatchery on Battle Creek . A total of 34,740 fish have gone over the Woodbridge Diversion Dam on the Mokelumne near Lodi through Dec . 13 , according to Michelle Workman , Fisheries and Wildlife Manager for the East Bay Municipal Utility District ( EBMUD ). 25,429 of those fish were adults , while 9,303 were grilse ( male / female 2 year olds ). Those numbers don ’ t add up to the total because a handful of early fish could not be sorted by male / female . The previous salmon record was set last year when the total run size was 28,865 , said Workman . The Mokelumne is a 95-mile-long river in northern California that flows west from the rugged central Sierra Nevada into the Central Valley and then into the Sacramento – San Joaquin River Delta , where it empties into the San Joaquin River-Stockton Deepwater Shipping Channel . The Mokelumne River Fish Hatchery has finished spawning salmon until next fall , with 15,378,285 green salmon eggs taken this season . “ We have provided over 5 million of those eggs to the Coleman National Fish Hatchery on Battle Creek ,” she noted . The Mokelumne River Fish Hatchery ’ s goal is to produce 8.9 million smolts ( juvenile salmon ) this coming spring . This includes 3.4 million for mitigation , 3 million for enhancement and 2.5 million for ‘ climate resilience ’ production . Why is the Mokelumne seeing record runs of fish ? “ There are lots of reasons that basically boil down to good communication and collaboration with DFW on overall management of this population ,” said Workman . “ Our hatchery incubation yields very high survival due to chillers and UV filters , our release strategies are very successful in yielding high survival to return , we had over 50,000 acre-feet of water for fall attraction this fall , and another year of a closed fishery left a lot of fish available for inland hatcheries and spawning grounds .” “ We continue maintaining suitable spawning habitat and flows in the river and have over 6,800 redds ( salmon nests ) in the river

Beautiful steelhead like this one are the reward for patient anglers fishing an array of lures on the Mokelumne River .

Photo courtesy of Samuel Yoro currently , so we are seeing success in both the hatchery production and in the river production ,” explained Workman . “ We are excited to see how the returns look 2-3 years out based on these record high runs !”

Steelhead — anadromous rainbow trout — are also showing in large numbers on the Mokelumne . A new record for the number of steelhead returning to the Mokelumne River was set in February of 2024 when a total of 1,749 steelhead , including 968 adults and 781 fish under 18 inches , returned to the system . The previous record for total steelhead was in 2018 when the hatchery reported 530 adults and 638 juveniles , a total of 1168 fish . However , there was another year when the total number of adults was over 700 fish . The hatchery has already started spawning steelhead this season . The facility has reported 379 fish to date — and now is right in the middle of the run , according to Workman .

“ I ’ m proud of EBMUD ’ s decadeslong dedication to sustaining the health of the Mokelumne River habitat and investing in fish hatchery operations ,” said EBMUD Board President Lesa

McIntosh . “ This historic salmon run is a testament to our science-driven management , cooperative relationships with neighbors on the river , and our collaboration with local , state and federal partners to enhance spawning grounds , operate our hatchery effectively , and protect vital natural resources .” The Mokelumne River is the primary drinking water source for over 1.4 million EBMUD customers in Alameda and Contra Costa counties . The not-for-profit public