Biological Opinions - Bureau of Reclamation

the KBPM. The scatter of modeled UKL elevations is presented in Figure 8.1 through Figure
8.12. For each month, Figure 8.1 through Figure 8.12 present simulated end-of-month UKL
elevations graphed relative to observed cumulative net inflow into UKL. The scatter of UKL
elevations shown on the monthly graphs defines the full range of elevations and effects in UKL
analyzed by this BiOp. Therefore, the graphs show the full range of expected outcomes of
implementing the proposed action, and provide a basis for evaluating whether hydrologic or
operational conditions are forcing UKL elevations outside the modeled range of elevations and
what has been analyzed in this BiOp.
In addition to the full range of expected UKL elevations, Figure 8.1 through Figure 8.12 also
present minimum elevation thresholds developed by USFWS for UKL, based on the modeled
results of the proposed action. The minimum elevation thresholds represent the extreme lower
limits of elevations that should be observed in UKL during the term of the proposed action, with
very limited exceptions that are described in more detail below. Assumptions underlying the
thresholds include:
The proposed action, including Conservation Measures, are implemented as described
above and in Reclamation’s BA (Reclamation 2012).
Minimum elevation thresholds are not management targets. The thresholds define
conditions that are outside the analyses conducted by USFWS for this BiOp.
Elevations in UKL will exhibit the patterns and magnitudes expected for particular
hydrologic and operational conditions modeled and described in the BA and in the Effects
of the Action (section 8) of this BiOp.
Elevations in UKL will be greater than the thresholds for all hydrologic conditions
observed during the POR, except for discrete situations caused by rare winter events.
The UKL elevation will be a specific distance above the threshold at the beginning of
each irrigation season, based on winter and early spring conditions. As the irrigation
season progresses, the distance between observed UKL elevations and the threshold
should not progressively decline.
The minimum elevation thresholds define UKL elevations outside the scope of USFWS
analyses, and provide for an early warning that aspects of hydrologic conditions or water
resource management are out of balance compared with the simulated and intended results of
implementing the proposed action. UKL elevations approaching a threshold indicate that
Reclamation must identify the reasons for the unexpected elevations and consult with the
Services regarding implementation of potential adaptive management actions to prevent violation
of the threshold. However, if adaptive management is unsuccessful at avoiding threshold
violations and the USFWS does not accept the rationale for the violation or mitigation of the
effects, the action will be declared to be outside of the USFWS analysis and may trigger
reinitiation of consultation.
The minimum elevation thresholds for UKL were developed by graphing the modeled monthend
UKL elevations as a function of cumulative net inflow into UKL. Thresholds define the
lower edge of the scatter of UKL elevations simulated in the proposed action. They were
developed by selecting points on the lower edge of the scatter, allowing for a 0.1 foot buffer (less
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