Biological Opinions - Bureau of Reclamation

conclusions in this BiOp regarding hydrologic effects of the action, NMFS compares the effects
of the proposed action to the Klamath River natural flow regime. NMFS acknowledges that the
historic discharge dataset at Keno is limited and likely does not represent the full range of
hydrologic conditions that occurred in the 1981-2011 POR. The 1981-2011 POR contains both
extremely wet (e.g. 1982, 1983, and 1984) and extremely dry (e.g., 1991, 1992, and 1994) water
years which likely encompasses the full range of hydrologic conditions NMFS expects to occur
in the next 10 years. The long term rainfall record for Klamath Falls, Oregon suggests that the
1905-1913 period had slightly above average precipitation, (i.e., 104 percent of average for the
period 1905 through 1994) with slightly above average runoff for much of the upper Klamath
Basin (Hecht and Kamaan 1996). However, the 1905-1913 annual hydrographs were likely not
representative of the full range of hydrologic conditions because very wet and very dry annual
hydrographs appear to be absent from this period (Trush 2007).
11.4.1.1.1 Characteristics of the Natural Flow Regime
Reclamation proposes to manage flows in the Klamath River in a manner that approximates the
natural hydrograph, represented by real-time climatological and hydrological conditions. For
this discussion, the natural hydrograph is defined by the 1905-1913 discharge dataset at Keno,
Oregon (Figure 11.4). The 1905-1913 Keno discharge dataset represents historic and relatively
unimpaired river flow before implementation of the Klamath Project and other human caused
factors influencing the current hydrological baseline (e.g., PacifiCorp’s dams, off-Project water
users). Reclamation’s actions of storing and delivering Project water, and meeting ESA needs of
endangered suckers, combined with other factors outside of Reclamation’s discretion, limit the
volume of water available for Reclamation to approximate the natural hydrograph (Figure 11.4).
Based upon our evaluation, greater than one third of the median annual UKL net inflow (1105
TAF) is diverted to the Project annually.
Under the proposed action, the average daily hydrograph at Keno, Oregon approximates the
shape of the natural hydrograph but will have a lower magnitude and duration of peak discharge
with a shift of more than one month, from the end of April to the middle of March, relative to the
historic average daily hydrograph at Keno for the 1905-1913 period (Figure 11.4). Additionally,
spring and summer discharge is substantially reduced. Historically, Klamath River discharge did
not reach base (minimum) flow until September. After implementation of the Project, minimum
flows occur in the beginning of July, a shift earlier in base flow minimum of roughly two
months. The proposed action hydrograph at IGD has a similar shape to the proposed action
hydrograph at Keno and illustrates the characteristics of the flow regime (shape, timing, and
variability) evidenced at Keno, but IGD has a higher peak magnitude and flow volume due to
accretions between Keno and Iron Gate dams (Figures 11.4 and 11.5).
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