Biological Opinions - Bureau of Reclamation

The source of the sediment is unknown, but likely is in part from runoff, some of which could
come from lands that use Project water.
Surface elevations in Tule Lake Sump 1A of 4,034.6 ft (1,229.8 m) from April through
September and 4,034.0 ft (1,229.6 m) from October through March appear to provide some areas
of water depth greater than 3 ft (1 m) for older juveniles and adults; however, depths of less than
4 ft (1.2 m) likely make suckers vulnerable to pelican predation, and there is continued concern
about the possibility of decreasing water depths in the future due to continued sedimentation
(USFWS 2008). However, maintaining higher lake elevations in Tule Lake is not feasible
because of the need to maintain certain maximum elevations to prevent flooding of surrounding
areas in wetter periods and to support feasible project operations. Therefore, the proposed
Project operations that are under the discretion of Reclamation are not likely to limit the
persistence of the non-reproducing populations of SNS and LRS suckers in Tule Lake Sump 1A.
8.3.8.4 Effects to LRS and SNS in Tule Lake from Water Quality
The proposed action will likely contribute to the poor water quality in the sumps, as a result of
the high nutrient concentrations of inflows and pesticide contamination of water reaching the
sumps, as discussed in section 7, Environmental Baseline, of this BiOp. Poor water quality in
Tule Lake may reduce the body condition and survivorship of individual suckers. Although, the
physical condition of adult suckers in Sump 1A is generally good (Hodge and Buettner 2007,
2008, 2009), we assume that adverse effects of poor water quality are more likely to affect young
suckers because of their higher metabolic rates. However, adverse effects to young suckers are
dependent on them being present. Because LRS and SNS are not known to reproduce in the
sumps because of the lack of suitable spawning habitat, young suckers are likely entering the
sump from upstream areas and young suckers have been put into the sump as a result of past
salvage efforts. Thus, at least small numbers of young suckers likely occur in the sump and any
that are present are likely to be negatively affected by adverse water quality that is partially a
result of Project operations. However, there is no evidence that these effects are limiting the
persistence of the LRS and SNS in Tule Lake.
8.3.8.5 Effects of Entrainment Losses of LRS and SNS in Tule Lake
There are five federally owned unscreened diversion points from Tule Lake sumps (R Pump, R
Canal, Q Canal, D Pumping Plant, N-12 Lateral Canal; USBR 2012). These diversions could
pose a threat to suckers in Tule Lake Sump 1A because of entrainment. However, this risk is
low because there are few young suckers present in the sump (Hodge and Buettner 2008, 2009).
Adult suckers are less likely to be entrained because of their better-developed avoidance
behavior and distribution in the sumps, which is mostly in offshore areas. Thus, the USFWS
concludes that levels of entrainment that would likely occur as a result of the proposed action in
Tule Lake are likely so small that it is not limiting the persistence of LRS and SNS in Tule Lake.
Summary of Effects to LRS and SNS Populations in Tule Lake Sump 1A
Based on the above analysis, the USFWS concludes the proposed action likely has minimal
adverse effects to suckers in Tule Lake Sump 1A. The primary concern is that proposed action
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