Tributary Confluence Passage Restoration and Enhancement

Recent research in the Klamath Basin, indicates that both summer and winter refugia associated with the lower reaches of Klamath tributaries are critical for the survival of juvenile salmonids and in particular, juvenile coho. Fisheries surveys have identified consistently high numbers of juvenile salmonids in habitats that function both as summer and winter refugia. Fish passage barriers include aggraded stream mouths where streams will either run sub-surface or become too shallow for fish to navigate because of large alluvial deltas. This problems has been exacerbated by past upslope disturbances such as wildfires, road failures and mining that have increased the sediment load particularly at the mouths of these tributaries. Many channels and stream mouths have been severely altered during past flooding (1955, 1964, 1997 and 2006), as described in the 1998 report titled, The Flood of 1997, by the Klamath National Forest, which links flood damaged stream channels to impacts from wildfire and road crossings. Chronic low flows in the mainstem Klamath and Scott have increased the impact of seasonal barriers at the mouths of tributaries.

The Yurok Tribe has conducted direct snorkel observation of thermal refugia sites for fifteen years, and has an extensive data set on the location and usage of these areas. We have noted the importance of cover, and the importance of fish passage into the tributary itself, particularly for coho salmon.

In this project, the Yurok Tribe used hand construction methods to improve fish passage and to install simple cover elements to thermal refugial areas. Tribal Fisheries personnel consolidated braided flow channels into a single coherent stream channel at Pecwan, Tully, Kepel, Pine, Roach and Bluff Creeks, and introduced simple cover elements at several of these sites as appropriate. Cover elements includde dead brush and/or trees (where safe), which will not be permanently anchored. The changing and alluvial nature of these sites precluded the construction of permanent features.

Project goal: Increase the connectivity at approximately six tributary confluence locations to enhance their ecological benefits.

Expected outcomes: Include increased use of these refugial areas, increased use of off-channel rearing sites by coho salmon, and decreased predation of these fish (due to cover).

PCSRF Goals, Objectives and Priorities addressed: Enhancing the availability and quality of salmon and steelhead habitat; Improving the status of ESA-listed SONC coho salmon; Addressing limiting factors (access to cool water areas in tributary streams) for ESA-listed SONCC coho salmon; Helping to ensure overall sustainability of naturally-spawning salmon and steelhead in the lower Klamath Sub-basin; helping to recover, conserve and maintain ESA-listed SONCC coho salmon; Helping to maintain salmon and steelhead for the exercise of the Yurok Tribes federally reserved fishing right; and protecting and restoring habitat for salmon and steelhead.