Biological Opinions - Bureau of Reclamation

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As with coho salmon fry, the adverse effects to coho salmon juvenile habitat in the Trees of
Heaven, Seiad Valley, and Rogers Creek reaches are likely to be somewhat moderated by the
flow variability incorporated into the proposed action when hydrological conditions in the upper
Klamath Basin are wet.
11.4.1.2.3.3 Water Quality
Water quality impairments in the Klamath River are most common in the late spring through
summer. Therefore, NMFS narrows the water quality analysis to the spring and summer. As
with most rivers, the water quality in the Klamath River is influenced by variations in climate
and flow regime (Garvey et al. 2007, Nilsson and Renöfält 2008). Because climate effects are
beyond Reclamation’s discretion, NMFS will focus in this section (NMFS addresses climate
effects in other sections of this BiOp) on the water quality effects resulting from controlled
flows, which are influenced by the proposed action. Water quality analysis conducted by
Asarian and Kann (2013) indicates that flow significantly affects water temperature, dissolved
oxygen, and pH in the Klamath River. Multiple, complex, and interacting pathways link flow to
water quality effects (Figure 11.19). In fact, of all the independent variables evaluated, Asarian
and Kann (2013) found that flow had the strongest effect on water quality. Some of these water
quality parameters, such as water temperature and dissolved oxygen are discussed further below.
Water Temperature
As discussed previously, the proposed action will reduce the volume of water released from IGD
during the spring. Water released from IGD influences water temperature in the mainstem
Klamath River, and the magnitude and extent of the influence depends on the temperature of the
water being released from the dam, the volume of the release, and meteorological conditions
(NRC 2004). As the volume of water decreases out of IGD, water temperature becomes more
responsive to local meteorological conditions such as solar radiation and air temperature due to
reduced thermal mass and increased transit time (Basdekas and Deas 2007). The proposed
action’s effect of reducing mainstem flows in the spring will result in longer flow transit times,
which will increase daily maximum water temperatures and to a lesser extent, mean water
temperatures in the mainstem Klamath River downstream of IGD during the spring (NRC 2004).
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