Biological Opinions - Bureau of Reclamation

at UKL during the 10-year term of the proposed action is essential to the survival and the
recovery of the LRS and the SNS given the important role that UKL plays in the conservation of
these species. We anticipate that adverse effects to the declining adult sucker populations in
UKL as a result of Project operations will be minimized through the proposed relocation of adult
suckers to UKL from Lake Ewauna and the proposed controlled propagation program, both of
which are discussed below.
8.3.4 Effects of the Proposed Action to the Lost River Subbasin Recovery Unit of
the LRS and the SNS
As described in section 7, Status of the Species, of this BiOp, the Lost River Basin recovery unit
for the LRS and the SNS consists of the following water bodies: (1) Clear Lake and tributaries;
(2) Tule Lake; (3) Gerber Reservoir and tributaries; and (4) the Lost River (USFWS 2013). This
analysis relies on the survival and recovery function assigned to each of these units to express the
significance of anticipated effects of the proposed Project operations on these species. The
proposed Project operations is likely to affect habitat availability for most LRS and SNS lifehistory
stages, including larvae, age-0 juveniles, older juveniles, and adults. There is no known
shoreline spawning in any of the water bodies in this recovery unit, so embryos and pre-swim-up
larvae will not be affected. Additionally, because there is no emergent wetland vegetation in
Clear Lake or Gerber Reservoir, the proposed action will not affect that habitat. High turbidity
in Clear Lake and Gerber Reservoir likely provides cover to early sucker life-history stages
similar to that provided by wetland vegetation in UKL (USFWS 2008).
8.3.5 Effects to LRSs and SNSs in Clear Lake
Clear Lake has sizeable populations of the LRS and the SNS, and may have the overall largest
SNS range-wide population (50,000 in UKL). Management of Clear Lake under the proposed action will continue to
provide an annual minimum surface elevation of not less than 4,520.6 ft (1,377.9 m) on
September 30 th of each year (USBR 2012).
Under the proposed action, Reclamation plans to estimate irrigation water supplies and ensure
lake levels stay above the minimum using a method similar to process that described in previous
consultations (USFWS 2002, 2008). Clear Lake management consists of the following.
Beginning about April 1 of each year, the April through September inflow forecast, current
reservoir elevation, estimated leakage and evaporative losses, and an end-of-September
minimum elevation of 4,520.6 ft (1,377.9 m) are used to predict available irrigation supplies for
Clear Lake (USBR 2012). The estimated water supply is frequently updated, based on revised
inflow forecasts and changes in surface elevations, through the irrigation season. In-season
updates inform the decisions to curtail or terminate irrigation deliveries to avoid going below the
minimum surface elevation (USBR 2012).
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