Very few South Fork issues capture the mind and emotion of fly fisherman and anglers in general like Palisades Dam operations. Palisades Dam is part of the U.S. Bureau of Reclamation's (BOR) Upper Snake River storage system. Currently, the dam is operated primarily as an irrigation storage facility that also provides some power generation and flood control protection. Operational issues that impact the South Fork fishery include winter flow levels and peaking operations associated with both irrigation deliveries and power generation, both of which can rapidly alter flow levels.
Many local residents recall the fish kill in the winter of 2000-2001 where hundreds of cutthroat and brown trout were photographed trapped in a desiccated South Fork back-channel. Such habitats are often dewatered during low flow years and drought cycles when winter flows below Palisades Dam reach perilously low levels. Trout Unlimited and Federation of Fly Fisherman members in the local Snake River Cutthroats Chapter have argued for years that winter flows should be higher to better protect juvenile and adult trout in the South Fork system. Further, local members have been vigilant once the irrigation season ends to work with the Idaho Department of Fish&Game to salvage fish where possible.
While the news is not all good, and flows have been far from optimum, The BOR has emphasized the need during the most recent drought years to maintain flows below Palisades Dam at approximately 1050 cubic feet per second (cfs). This is in light of the fact that during earlier drought periods in the 1960s, 70s, and 80s, flows dropped as alarmingly low as 550 and 750 cfs. Trout Unlimited is currently participating in a working group that includes the irrigation community and other Upper Snake River stakeholders to talk about river health issues. Historically, communication between the irrigation community and conservation interests has been sparse and coordination non-existent. Hopefully, these talks will lead to a better understanding of both interests, and creative solutions in the future.
Trout Unlimited is also enthused about some of the current research efforts examining the ecological health of the South Fork system. The BOR is in the midst of a major study effort referred to as the Ecologically Based System Management Project (EBSM). One of the goals of the study is to better understand and attempt to balance traditional uses (e.g., irrigation and flood control) with other demands on the Snake River and reservoir system for water related resources (e.g., threatened and endangered species, fish, wildlife, recreation, water quality, and economics). This will be done from a comprehensive ecosystem approach, considering the long term management of the river and reservoir system. This study will assist in realization of these goals through examination of linkages between main channel and floodplain habitats, the inter relationship between hydrologic flows, sediment load, and surface- and groundwater interactions. This study will establish reference based floodplain conditions, and evaluate the river floodplain interconnectivity and linkage of habitats. Recommendations coming from this study will include the hydrologic and geomorphic modifications necessary for restoration of ecosystem function, and other possible mitigation alternatives.
Any changes to long-term operational regimes in the Upper Snake River will depend on partnerships and creative solutions developed in tandem with the irrigation community and BOR. TU is committed to working within this type of framework.