Biological Opinions - Bureau of Reclamation

Although suckers in Sump 1A look healthy, based on observations of their condition factor
(body fullness and low incidence of disease and parasites; Hodge and Buettner, 2007-2009), lack
of spawning habitat probably prevents them from reproducing. These, populations appear to be
maintained by emigration from elsewhere, probably UKL (USFWS 2008). Water levels in the
Tule Lake sumps have been managed according to criteria set in previous BiOps (USFWS 2002
2008). The proposed action will continue to manage Tule Lake Sump 1A for a surface elevation
of 4,034.6 ft (1,229.8 m) from April through September and an elevation of 4,034.0 ft (1,229.6
m) from October through March to provide habitat with areas of water depth greater than 3 ft (1
m) for older juveniles and adults (USBR 2012).
8.3.8.1 Effects to Adult LRS and SNS Spawning and Migration in Tule Lake Sump 1A
A minimum surface elevation of 4,034.6 ft (1,229.8 m) from April 1 to September 30 in Sump
1A was determined to provide sucker access to spawning areas below Anderson Rose Dam
(USFWS 2002, 2008). The proposed action, which continues to manage Sump 1A for a surface
elevation of 4,034.6 ft (1,229.8 m) from April through September, is not likely to adversely
affect sucker access to areas below the Anderson Rose Dam due to surface elevations in the
sump when conditions, such as flows, encourage spawning. However, it appears that successful
reproduction is limited by a lack of suitable substrates and flows at the dam.
It is not clear to what degree Project operations are responsible for the variable flows in the Lost
River because flows are affected by run-off; however, flows are regulated by Anderson Rose
Dam, which is part of the Project. Thus, Project operations are in-part responsible for these
variable flows and the loss of spawning substrate. Therefore, although proposed Project
operations will provide elevations that support access to areas that historically were used for
spawning, lack of suitable substrate due to past habitat alterations and past operational flows
continues to limit the ability of LRS and SNS populations in Tule Lake to spawn unless dams are
removed, flows regulated, and significant habitat restoration efforts are implemented.
8.3.8.2 Effects to LRS and SNS Larvae and Age-0 Juveniles Habitat in Tule Lake
The wetland area of Tule Lake Sump 1A near the Lost River outlet likely provides habitat for
larvae and young juveniles, assuming that larval and age-0 juvenile suckers occur in Tule Lake
and utilize nearshore and vegetated habitats similar to suckers in UKL. The minimum elevation
of 4,034.6 ft (1,229.8 m) should provide adequate habitat for larval and juvenile LRS and SNS
life stages because the proposed water levels will inundate hundreds of acres of emergent marsh
habitat (USFWS 2008). Thus, the proposed action at Tule Lake is unlikely to limit larval and
age-0 juvenile habitat.
8.3.8.3 Effects to Habitat for 1+ Juveniles and Adult LRS and SNS in Tule Lake
Water depth as cover for age 1+ suckers (age 1+ juveniles includes older juveniles) is limited
due to the shallow depth of Tule Lake sump 1A, which are mostly less than 4 ft (1.2 m). One
reason for the shallow depths is because sediment is being transported downstream in the Lost
River and collects in Tule Lake which is the terminus of the Lost River (USFWS 2002, 2008a).
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