Yakama Nation Sunnyside Dam Monitoring & Lower Yakima River Monitoring

The purpose of this project is to assess passage of smolts through the Sunnyside Diversion and through the mouth of the Yakima River of Central Washington. The assessment will be focused on downstream survival of entrained fish into the Sunnyside irrigation canal and at the mouth of the river. Ongoing PIT tag detection is important to assessing the impact of the Sunnyside Diversion on migrating juvenile salmonids, the benefits of measures to reduce entrainment into Sunnyside Canal, and the results of future structural and operational changes at the diversion. Every year more than 40,000 PIT-tagged juvenile salmon and steelhead leave upstream release sites toward the Sunnyside Diversion, and most of them pass the diversion when water is being diverted into Sunnyside Canal.



This entrainment estimate requires a large number of PIT tag detections at Prosser, McNary, John Day and Bonneville dams. Only a fraction of the tags passing each of these sites can be detected. Because of declining detection probabilities at existing sites, this research would benefit from an additional site for detecting tagged fish as they move downstream from the Sunnyside Diversion.



Locating a PIT tag array near the mouth of the Yakima River can increase its utility. Researchers and fisheries managers in the Yakima Basin need to estimate survival of juvenile salmon and steelhead from a variety of upstream locations to the mouth of the Yakima River, not only to compare the performance of different release groups, but to assess the impacts of passage conditions through the entire river and the benefits of habitat restoration and flow management on juvenile survival. At present, McNary Dam on the Columbia River is the closest detection site, 43 miles downstream from the mouth of the Yakima River. Having to use McNary Dam as the endpoint for Yakima River survival analyses reduces their reliability by combining Yakima River and Columbia River passage effects. Several candidate sites have been identified for deploying a mobile PIT tag detection system in the lower Yakima River near its confluence with the Columbia River.



Monitoring will also be conducted in conjunction with the new 2022 Sunnyside Dam Fish Guidance System (SDFGS). The SDFGS consists of two parts, one is an in-river guidance boom the second is construction of an overshot gate. The SDFGS goal is to prevent fish, primarily migrating juvenile salmon, from being diverted into the Sunnyside Dam diversion canal but is not expected to eliminate smolt entrainment that varies over the outmigration season due to river flows at the site. Salmon stocks impacted by the Sunnyside Dam and diversion canal are: ESU listed steelhead, Chinook, Coho, and Sockeye Salmon. The project will include PIT tag detections at the lower Yakima River PIT tag barge site and alongside Sunnyside diversion existing arrays while incorporating benefits from the lower river passage monitoring. PIT tag arrays downstream of Sunnyside dam and at the fish bypass pipe of the irrigation canal (YKFP, M&E program) will be used.



Worksite #1 Sunnyside Dam Proposed Work:



A PIT tag array will be designed and constructed for placement at Sunnyside Dam irrigation canal. Annual upstream PIT tag releases of multi-species salmon and ESU listed Steelhead will allow for development survival estimates based on passage route. Estimates will be linked to upstream releases, Sunnyside arrays site and detections, downstream PIT tag detections at multiple Yakima River and Columbia River PIT tag interrogation sites.



Worksite #2 Mouth of the Yakiama River

A PIT tag array will be designed and constructed for placement near the mouth of the Yakima River. Annual upstream PIT tag releases of multi-species salmon and ESU listed Steelhead will allow for development of survival estimates based on passage route. Estimates will be linked to upstream releases, Sunny

YN has worked to enhance and reintroduce salmon and Steelhead populations in the Yakima River Basin, Sunnyside Dam fish passage facilities have been identified as a significant source of mortality for these populations. Current and past Yakima River studies have shown large numbers of juvenile salmon are entrained into Sunnyside Dam Diversion Canal through the head gate as they are attempting to migrate downstream past the dam. Juvenile salmon that enter the canal have a much lower survival rate than those that pass the dam through the sluicegate, fish ladders, or over the dam crest. A fish guidance structure (SDFGS) is being completed in 2022 to increase overall fish survival by discouraging fish from entering the canal and by increasing the safety of the sluice gate passage route. Evaluation of the SDFGS is critical to protect the basins salmon and steelhead populations.