The Department of Water Resources’ consultant on in the WaterFix tunnels hearing testified:
“But for those Smelts that are occurring in that area, the North Delta diversions will be designed to fish agency protective standards”… “That opening, based on analyses, would prevent entrainment of Smelts that are greater than about 21 to 22 millimeters.”1
“In the EIR/EIS, the only significant and unavoidable impact that we found was for Striped Bass and American Shad. This is because of entrainment of early life stages at the North Delta diversions. These are species that spawn upstream of the North Delta diversions, in large part…..2
For American Shad, studies suggest that many American Shad were upstream of the Delta and, therefore, when they’re coming down into the Delta, they would be sufficiently large to be screened by the North Delta diversions.”
Delta smelt spawn in the north Delta in late winter and early spring. Their juveniles occur through summer. Their young would be highly susceptible to entrainment throughout spring (Figure 1).
Sturgeon, both green and white, spawn above the Delta in the lower Sacramento River in early spring. Their larvae and early juvenile stages reach the Delta in spring at a size highly vulnerable to entrainment (Figure 2).
American shad spawn in the lower Sacramento River and tributaries in late spring and summer. Their larvae and early juveniles are prevalent in the north Delta in late spring and would be highly vulnerable to entrainment (Figure 3).
Striped bass spawn predominantly in the lower Sacramento River in spring. Their larvae reach the north Delta in May and June, and would be highly vulnerable to entrainment (Figure 4).
Splittail spawn in the lower Sacramento River floodplain in spring. Their early juveniles reach the north Delta usually in May and would be highly vulnerable to entrainment (Figure 5).
Prickly sculpin, an abundant native Delta fish, spawn in the lower Sacramento River in late winter and their larvae are found in the north Delta in early spring and would be highly vulnerable to entrainment (Figure 6).
Sacramento sucker spawn in Valley rivers in spring. Their larvae and early juveniles are present in the north Delta throughout spring and would be highly vulnerable to entrainment (Figure 7).
Non-native threadfin shad, the most abundant forage fish in the Delta, spawn from late spring into summer throughout the Delta and lower rivers. Their larvae and early juveniles are prevalent in the north Delta in late spring and early summer, and would be highly vulnerable to entrainment (Figure 8).
Summary and Conclusions
Larval and early juvenile lifestages of many Delta fishes would be highly vulnerable to entrainment through the screens of the proposed WaterFix north Delta intakes. Juvenile/fry of these and other species (salmon3) would be highly vulnerable to impingement and predation at the screens.
- WaterFix hearing transcript, 2/23/18, Page 124, line 2: Dr. Greenwood testimony at State Board WaterFix hearing. ↩
- Id., Page 156, line 6. Note that many shad and striped bass spawn their buoyant eggs in the area of the proposed intakes and immediately upstream, as well as in the lower Feather, Sacramento, and American rivers. Nearly all the eggs and newly hatched larvae would pass the proposed CWF intakes. ↩
- Much of the wild salmon production from the American and Feather rivers’ fall-run populations comes from fry (30-50 mm) leaving these rivers in winter. Winter is the peak period of proposed north Delta diversions of the WaterFix project. These fry would not be protected by the proposed WaterFix screens. ↩