Yakama Nation Sunnyside Dam Monitoring & Lower Yakima River Monitoring

The purpose of this project was to assess passage of smolts through the Sunnyside Diversion and through the mouth of the Yakima River of Central Washington. This assessment 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.



For Sunnyside, we continued to use existing antenna systems in the canal to monitor survival through the bypass system. Improvements to the trash rack antennas have increased overall detection efficiency of the antenna system. These data will be reported on in 2026 following the outmigration season.



For the lower river monitoring portion, using PCSRF funds, the YN purchased a PIT barge for the mouth of the Yakima River, acquired necessary permits and installed the barge in January of 2026. Although several hundred juvenile salmonids have been detected with the barge since the installation, analysis of these data will be done after the 2026 outmigration is complete.

Washington Department of Fish and Wildlife cooperated in the installation and development of research of fish passage monitoring for the lower Yakima River PIT tag barge. The WDFW supplied the necessary guidance for the permitting and installation of the lower Yakima River PIT tag barge, and coordination between YN and WDFW occurred as co-managers. The entrainment estimate required a large number of PIT tag detections at Prosser, McNary, John Day and Bonneville dams.



Monitoring was also 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. Preliminary numbers for passage route and downstream detections are available for the site.



Worksite #1: Sunnyside Dam - PIT tag detections at the lower Yakima River worked with the Sunnyside irrigation diversions existing arrays and which allowed for development of survival estimates based on passage route for annual upstream PIT tag releases of multiple salmon and ESU listed Steelhead. Estimates were linked to upstream releases through detections at existing Sunnyside arrays and downstream lower Yakima River Pit barge detections alongside multiple Yakima River and Columbia River PIT tag interrogation sites. Analysis for detections at Sunnyside along with corresponding detections at downstream arrays were conducted following the outmigration season in 2026. Below are pictures of the trash rack antennas deployed at Sunnyside dam. Information on this site can be found at https://www.ptagis.org/Sites/InterrogationSites?code=SSJ



Worksite #2: Mouth of Yakima River - A PIT tag array was 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 allowed for development of survival estimates based on passage route. Estimates were linked to upstream releases, Sunnyside PIT tag detections, and downstream PIT tag detections at multiple Yakima River and Columbia River PIT tag interrogation sites. The “Lower Yakima Barge” was installed in January of 2026. Currently over 500 smolts have been detected leaving the Yakima River. Analysis for these detections were conducted following the outmigration season in 2026. Below are pictures of the deployed PIT barge. Information on the Lower Yakima Barge can be

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.