Biological Opinions - Bureau of Reclamation

consists of approximately 29,000 acres of irrigated land with an estimated annual irrigation
withdrawal of approximately 81,070 acre feet per year (Van Kirk and Naman 2008).
Agricultural diversions in both the Shasta and Scott rivers in some years, especially dry water
years, can virtually dewater sections of these rivers, impacting coho salmon within these streams
as well as those in the Klamath River.
There are two other diversion systems within the Klamath River Basin that affect the action area
for purposes of NMFS’ BiOp. Fourmile Creek and Jenny Creek diversions transfer water from
the Klamath River Basin into the Rogue River Basin. Estimated annual (1960 to 1996) out of
basin diversions from the Fourmile Creek drainage of the Klamath River basin to the Rogue
River Basin was approximately 4,845 acre-feet. Net out of basin diversions from the Jenny
Creek drainage of the Klamath River Basin to the Rogue River Basin were approximately 22,128
acre-feet (38,620 acre-feet exported - 16,492 acre-feet imported). Thus the total average annual
(1960 to 1996) diversions from the Klamath River Basin to the Rogue River Basin was 26,973
acre-feet (La Marche 2001).
As the value of farm lands increased throughout the Klamath River Basin, flood control
measures were implemented. During the 1930s, the U.S. Army Corps of Engineers implemented
flood control measures in the Scott River Valley by removing riparian vegetation and building
dikes to constrain the stream channel. As a result of building these dykes (banking), the river
became more channeled, water velocities increased, and the rate of bank erosion accelerated. To
minimize damage, the Soil Conservation Service (now known as NRCS) in Siskiyou County
planted willows along the stream-bank and recommended channel modifications take place
which re-shaped the stream channel into a series of gentle curves. The effectiveness of these
actions has not yet been measured.
There has been a recent decline in UKL outflows since the 1960s, which is likely due to
increasing diversions, decreasing net inflows, or other factors (Mayer 2008). There have been
declines in winter precipitation in the upper Klamath Basin in recent decades and declines in
upper-Klamath Lake inflow and tributary inflow, particularly base flows (Mayer 2008).
Declines in tributary base flow could be due to increase consumptive use, in particular,
groundwater use, and/or climate changes. Agricultural diversions from the lake have increased
over the 1961 to 2007 period, particularly during dry years (Mayer 2008). Declines in Link
River flows and Klamath River at Keno flows in the last 40-50 years have been most pronounced
during the base flow season (Mayer 2008), the time when agricultural demands are the greatest.
Consumptive use of water is expected to negatively impact one or more of the VSP criteria for
the interior Klamath populations because it reduces summer and fall discharge of tributaries that
the populations use (Van Kirk and Naman 2008); and low flows in the summer have been cited
as limiting coho salmon survival in the Klamath Basin (CDFG 2002a; NRC 2004). Specifically,
the spatial structure, population abundance, and productivity can be impacted by agricultural
activities. Altered flows likely interfere with environmental cues that initiate distribution of
juvenile coho salmon in the river, alter seaward migration timing, and potentially impact other
important ecological functions, leaving juveniles exposed to a range of poor quality habitat, and
prolonged exposure to stressful over wintering and summer rearing conditions (NMFS 2010a).
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