Yakama Nation Sunnyside Dam Monitoring

The purpose of this project is to assess passage of smolts through the Sunnyside dam irrigation canal on the Yakima River of Central Washington. The assessment will be focused on downstream survival of entrained fish into the Sunnyside irrigation canal. Monitoring will 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. Since the construction of the Dam and diversion salmon have experienced a high rate of entrainment into the irrigation canal, downstream survival for entrained smolts have much higher rates of mortality than smolts that pass over the dam (Yakima River Smolt Survival Study, Kock et. al, in progress). Salmon stocks impacted by the Sunnyside Dam and diversion canal are: ESU listed steelhead, Chinook, Coho, and Sockeye Salmon. Estimates of survival are in progress for various salmon smolts via an acoustic telemetry study currently in progress within the Yakima Basin. Preliminary numbers for passage route and downstream detections are available for the site.


A PIT tag array at this site is ideal as there are numerous upstream releases of PIT tagged smolts and multiple PIT interrogation downstream of the site within the Yakima and Columbia Rivers. This PIT tag array will be designed and constructed by Westfork Environmental (quotes are available) and placed within the irrigation canal. This array will be used in conjunction with existing PIT tag arrays downstream of Sunnyside dam and at the fish bypass pipe of the irrigation canal (YKFP, M&E program). Survival estimates based on passage route will be dependent on annual upper basin PIT tag releases of yearling Chinook, sub-yearling Chinook, Coho, and Steelhead smolts. These tagged fish will be assessed for survival using a Mark-Recapture analysis relying upon downstream PIT tag detections at the Chandler Juvenile Facility and Columbia River PIT interrogation sites. Data for annual PIT tagged smolts will be provided to Pacific States Fisheries and will be made available to the public via the PTAGIS website. Interrogations at the Sunnyside array will be uploaded to the PTAGIS website and also be made available to the public. Other information gathered at the site will provide critical data for travel time comparisons at varying river flows and planned pulsed flows that promote smolt survival. The array will also provide a better understanding of delayed migration for smolts that enter the canal. This data gathered will also assist in identifying key variables affecting passage route selection such as river flow and gate operation. Installation of the PIT tag array would occur in the fall/winter of 2022. Data gathering occur during the smolt outmigration season in 2023 and 2024. Yearly project updates will be produced along with a final multi-year report scheduled for early 2025.


Worksite #1 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.

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.