In a 10/19/2023 post, I discussed how the lack of access to Folsom’s deep cold-water-pool results in delayed natural and hatchery spawning of American River fall-run salmon.  During the 2020-2022 drought, Reclamation released water from the lower-level power bypass to provide the cold water (<55ºF) salmon need for spawning (see Figure 1).  However, this fall 2024 Reclamation has chosen not to use the power bypass to release cold water (Figure 2), despite higher storage levels than during the recent drought (Figure 3).  Lack of cold water delays natural spawning and hatchery egg taking, to the detriment of egg viability and fry production.

Figure 1. Water temperature of water released from Folsom Dam, Oct-Nov 2021. Late October drop in water temperature was from release of cold water from lower level outlet. Also shown is recent average for previous 7 years.

Figure 2. Water temperature of water released from Folsom Dam, Oct-Nov 2024.

Figure 3. Folsom Reservoir storage levels 2015-2024.

Figure 4. Photo of closed-gate entrance to Nimbus Hatchery fish ladder 11/14/2024.