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Biological Opinions - Bureau of Reclamation

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warm spring conditions continue over the ten-year action period (Hamlet et al. 2005, Regonda et<br />

al. 2005, Stewart et al. 2005, Knowles et al. 2006, Meehl et al. 2007, Mayer and Naman 2011),<br />

NMFS anticipates early peak flows and reduced late spring accretions from the snowmelt driven<br />

Scott River watershed.<br />

In previous consultations on <strong>Reclamation</strong>’s Project, the ability to model and evaluate the range<br />

<strong>of</strong> daily flow variability has been constrained to monthly or biweekly time-step output. Under<br />

the proposed action, IGD flows are a result <strong>of</strong> daily calculations described in detail in the<br />

proposed action section and incorporate several key indicators <strong>of</strong> natural hydrologic conditions<br />

(Williamson River flow, UKL storage, accretions below Link River Dam, etc.). NMFS<br />

evaluated the daily change in flow at IGD under the proposed action versus the observed daily<br />

change in flow observed at IGD for the POR to evaluate whether the proposed action will result<br />

in a trend <strong>of</strong> the Klamath River hydrograph towards, or away from, the natural flow regime in<br />

terms <strong>of</strong> flow variability.<br />

Each daily flow change <strong>of</strong> 30 cfs and higher was enumerated as a flow change likely to occur<br />

under the proposed action because 30 cfs is the smallest incremental flow change that NMFS<br />

reasonably expects to be implemented due to PacifiCorp’s operational constraints (Hemstreet<br />

2013). For the POR, 4,487 days out <strong>of</strong> 11,322 days (40 percent) demonstrate a change in daily<br />

flow <strong>of</strong> 30 cfs or higher under the proposed action, compared to 3,295 days out <strong>of</strong> 11,322 days<br />

(29 percent) for observed (Table 11.6). On an annual basis by water year, the percentage <strong>of</strong> days<br />

exhibiting daily flow changes <strong>of</strong> 30 cfs and higher is greater most years under the proposed<br />

action (Figure 11.12). The extent <strong>of</strong> variability is distributed relatively equally between the<br />

October through February and March through September time periods (Table 11.6).<br />

Table 11.6. Percentage <strong>of</strong> days exhibiting daily flow changes <strong>of</strong> at least 30 cfs for the proposed action and<br />

observed discharge at IGD.<br />

TIME PERIOD<br />

Daily Flow<br />

Water<br />

Change<br />

Oct-Feb Mar-Sep<br />

Year<br />

Proposed Action 40% 38% 41%<br />

Observed 29% 27% 30%<br />

257

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