Despite a record water supply in 2017, water operations in the Sacramento Valley are already threatening salmon and sturgeon because water managers are not meeting flow and water temperature targets and regulators are not enforcing them.

The water temperature of the Sacramento River at Red Bluff (river mile 240) exceeds the target of 56^oF in the Salmon Biological Opinion, water right permits, and Basin Plan (Figure 1a).  The water temperature at Red Bluff (Figure 1a) is also approaching the 60^oF tolerance limit for salmon and sturgeon eggs and embryos.  The water temperature in the lower Sacramento River at Wilkins Slough (river mile 125) exceeds the 65^oF tolerance limit for sturgeon larvae and approaches the 68^oF Basin Plan tolerance limit for migrating juvenile and adult salmon and sturgeon (Figure 1b).  To protect migrating salmon and sturgeon, water managers need to maintain a flow in the lower Sacramento River of at least 10,000 cfs through the summer of this very wet year (Figure 2).

Figure 1. Sacramento River water temperature at (a) Red Bluff (river mile 240) and (b) Wilkins Slough (river mile 125) during May 2017. Red lines depict Basin Plan targets. Source: CDEC.

Figure 2. Mean daily river flow in the lower Sacramento River at Wilkins Slough (river mile 125) during May 2017. Source: USGS.