In an August 15, 2016 post on its Pacific Southwest Region website, the US Fish and Wildlife Service observed that the numbers of young green sturgeon have gone up this year in trap collections below the Red Bluff Diversion Dam.² The article notes that this could represent an increase in the population. Joe Heublein, NMFS’s Green Sturgeon Recovery Coordinator, is also cautiously optimistic, according to the article.

Since 2012, gates at the Red Bluff dam have not hindered adult sturgeon from moving upstream past the dam to reach spawning grounds. Since 2016 was the first non-drought year since 2012, it seems likely that there should be an increase in the capture of recently spawned juveniles migrating downstream past the dam.

Missing from the story, however, is the fact that these juvenile sturgeon faced a particularly tough journey between Red Bluff and the Bay this summer, as discussed in my previous post on green sturgeon. Low flows and high water temperatures were a serious problem for the young sturgeon in the lower reaches of the Sacramento River in 2016. Unless their downstream rearing and migratory habitat is improved, the green and white sturgeon populations will have a bleak future.

The presence of young is a good sign. The species is long-lived, and thus it is not too late to recover this state and federally listed endangered fish. Getting rid of the Red Bluff diversion Dam five years ago was a big first step. The focus now should be on late spring through summer Lower Sacramento River habitat.

Since the beginning of summer 2016, conditions have improved (Charts 1 and 2). In August, flows at Wilkins Slough increased to 5000-7000 cfs, and water temperatures were down near 70°F. In late May and June, water temperatures at Red Bluff (Chart 3) were near lethal (68°F) for the really small fish, and were most likely worse not far downstream (Chart 2). Now temperatures are closer to the Basin Plan’s prescribed 56°F at Red Bluff and 68°F at Wilkins Slough.

The initial problem this year was the result of reduced releases from Shasta Reservoir to save its cold water pool for winter-run salmon, combined with normal agricultural water allocations in the Sacramento Valley. Recent improvements are the result of the normal late summer reductions in irrigation demands. In the future, Basin Plan objectives should be met by a reduction in Sacramento Valley water allocations when water is not sufficient to allow higher overall summer reservoir releases from Shasta.