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Nor-Cal Guides & Sportsmen's Association

Hatchery Salmon Releases into the Sacramento River in April 2025

Photo Credit: Wilkins-Slough

By Tom Cannon / thomascannon0@gmail.com

Beginning in mid-April millions of hatchery salmon smolts 3-4 inches long have been released into the Sacramento River from near Red Bluff downstream to near Colusa (see map). These hatchery smolts along with wild smolts gradually move downstream through the lower river, Delta, and into San Francisco Bay through the spring.

During their journey, the young salmon need adequate streamflow to provide healthy water temperatures in the 12-17^oC (54-64^oF) range to maximize their growth, survival, feeding, and movement.[1]  Higher temperatures cause stress, poor growth, disease, higher susceptibility to predation, and hinder smoltification (ability to enter saltwater).

Reclamation supported the salmon releases with two pulse flow releases from Shasta Dam – one in late April and one in early May (Figure 1). However, streamflows were insufficient to maintain water temperatures below the stress level of 17^oC (Figures 2 and 3).  Juvenile salmon continue to emigrate downstream in the lower Sacramento River, through the Delta, and into the Bay (Figures 4 and 5) and will do so through spring.  Despite 2025 being a wet year and millions of “extra” salmon smolts being released into the Sacramento River, flows as of May 10 have been reduced and water temperatures increased to highly stressful levels (20^oC, Figure 6) with over a month to go before the end of spring.

I recommend Shasta releases be increased to maintain Wilkins Slough flow at least at 10,000 cfs and water temperatures below 18^oC (65^oF) through the spring salmon smolt emigration season.  In addition, daily average Freeport flows should be a minimum 20,000 cfs and Delta outflow should not fall below 10,000 cfs.  If these minimum conditions are not met, smolt salmon survival to the ocean will suffer in this otherwise wet water year further limiting salmon recovery.

[1] https://www.noaa.gov/sites/default/files/legacy/document/2020/Oct/07354626288.pdf

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