Biological Opinions - Bureau of Reclamation

The Sprague, Williamson, and Wood Rivers are tributaries to UKL, and affect its water quality
because they provide inflows to the lake and downstream habitats, and transport suspended
sediments, nutrients, organics, and other particulate and dissolved constituents to the lake. The
major detrimental effect to suckers in the tributaries is degraded habitat due to stream and
watershed alterations. The tributaries also appreciably affect suckers through the export of
nutrients, especially phosphorus, and reduced inflows to UKL as a result of upstream diversions.
Although they are not part of the action area, these rivers contribute to baseline conditions within
the action area.
Historical activities impacting the UKL watershed and tributaries include timber harvest,
agricultural development, wetland loss and alteration, loss of beavers, hydrogeomorphic
alterations to watercourses and riparian zones, and water diversions (Risley and Laenen 1999,
ODEQ 2002, Bradbury et al. 2004, Eilers et al. 2004, Perry et al. 2005). Although most of these
activities are historical, some continue to negatively affect the UKL because they are the main
causes of the increased erosion and loading of nutrients, particularly phosphorus, in the
watershed (McCormick and Campbell 2007).
Lakes, especially shallow ones like UKL, which averages about 6 ft (2m) deep, can be strongly
affected by their watersheds because nutrients transported into the lakes are readily available for
algae growth. Nutrients in deeper lakes can be isolated from surface-dwelling phytoplankton
(suspended algae) because the lakes develop a warm-water layer (thermocline), which prevents
nutrients in deeper water from reaching the surface to facilitate algae growth. Additionally,
diking and draining in UKL has resulted in the loss of nearly 70 percent of its fringe wetlands,
and water pumped from these areas into the lake contains high concentrations of phosphorus,
thus further degrading water quality (Snyder and Morace 1997, ODEQ 2002, ASR 2005). The
decline in UKL water quality also affects water quality downstream in the mainstem Klamath
River due to the transfer of large amounts of organic matter, with an associated high biological
oxygen demand, from UKL to downstream water bodies (Doyle and Lynch 2005, Deas and
Vaughn 2006, ODEQ 2010). However, this is exacerbated by discharges from two wastewater
treatment facilities and untreated stormwater discharges. Massive die-offs of adult suckers
occurred in UKL during the 1990s that were attributed to adverse water quality and resultant
disease (Perkins et al. 2000b).
Adverse water quality directly impacts the LRS and the SNS resiliency by decreasing survival
and productivity. Adverse water quality indirectly affects the LRS and the SNS through algal
toxins and interactions with pathogens, parasites, predators, and competitors that are either more
tolerant of impaired water quality than suckers or benefit from the conditions created by nutrient
enrichment. Based on water quality criteria examined by Morace (2007) and Martin (USGS,
pers. comm., 2012), suckers are exposed to multiple stressors simultaneously or at least over a
period of weeks, and water quality stress could last for several months, most often from July
through September. This is most likely to affect age-0 juvenile suckers because they start
appearing in July when conditions can be poor and have limited ability to move the distances that
might be necessary to avoid adverse conditions. Adult suckers can move into Pelican Bay, and
thus have the potential to avoid poor water quality (Perkins et al. 2000b, Banish et al. 2009).
However, adults cannot always avoid stressful conditions, as the die-offs in the 1990s seem to
suggest (Perkins et al. 2000b).
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