Biological Opinions - Bureau of Reclamation

into the Pelican Bay water quality refuge area. However, new bathymetric data show that water
depths near Pelican Bay are deeper than previously recorded (USBR 2012). While the updated
bathymetric data have not undergone a detailed quality assurance/quality control (QA/QC)
review, bottom elevations in Pelican Bay have been corroborated by Reclamation (M. Neuman,
USBR, pers. comm. 2013).
These new data indicate that bottom elevations at the entrance to Pelican Bay are at
approximately 4,133.0 ft (1,259.7 m) to 4,134.0 ft (1,260.0 m; USBR 2012). This is several feet
lower (deeper) than we assumed in 2008. During very dry conditions below the 5 percent
probability for lake levels, the proposed action is likely to result in UKL surface elevations
below 4,138.2 ft (1,261.3 m) by the end of September (Table 8.1 and Table 8.6). Three years out
of 31 modeled years had an end-of-September elevation of 4,138.2 ft (1,261.3 m). The lowest
elevation in the modeled POR that constitutes the proposed action is 4,137.7 ft (1,261.2 m). At
this elevation there would be a minimum water depth of at least 4.2 ft (1.3 m) at the entrance to
the bay (Table 8.7).
Table 8.7. Water depths at the entrance to Pelican Bay at various UKL elevations. The minimum bottom
elevation at the entrance to the bay is approximately 4133.5 ft (1,259.9 m; Reclamation 2012, Table 7-10).
Lake Surface
Elevation (ft)
4,143.0
(1,262.8 m)
4,142.5
(1,262.6 m)
4,142.0
(1,262.5 m)
4,141.5
(1,262.3 m)
4,141.0
(1,262.2 m)
4,140.5
(1,262.0 m)
4,140.0
(1,261.9 m)
4,139.5
(1,261.7 m)
4,139.0
(1,261.6 m)
4,138.5
(1,261.4 m)
4,138.0
(1,261.3 m)
Depth of Entrance to
Pelican Bay (ft)
9.5
(2.9 m)
9.0
(2.7)
8.5
(2.6 m)
8.0
(2.4 m)
7.5
(2.3 m)
7.0
(2.1 m)
6.5
(1.9 m)
6.0
(1.8 m)
5.5
(1.7 m)
5.0
(1.5 m)
4.5
(1.4 m)
LRS and SNS that are unable to enter Pelican Bay could be at a higher risk from the effects of
adverse water quality if conditions occur similar to those in the 1990s that led to catastrophic dieoffs
of adult suckers (Perkins et al. 2000b). In 1996, over 4,000 adult suckers were found dead
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