This contract will result in the completion of one final design for the Brush Creek site, four 60% designs (two on Gate Creek, two on Grouse Creek) and five 30% designs (two on Twin Creek, three on Deep Creek) to correct fish passage barriers. Two barriers on Goose Creek that were originally part of this design contract were corrected in FY23 under contract # 90903. One barrier on Pole Creek that was originally part of this contract is expected to be corrected in FY25. The 13 fish passage barriers are on tributaries to the Lower Chiwawa River, and the correction of these barriers will improve connectivity to cold, clean, and complex habitat, while maintaining and improving ecosystem functionality vital to the persistence and recovery of ESA-listed species.

Work to complete designs for the 13 culverts was initiated in FY22 under the agreement #88609. In FY22 initial data collection and planning began for all 13 culverts. This work included site visits with our engineer, the Forest Service, WDFW and other project stakeholders. We collected watershed data, topographic information, and steam specific information for each site. Hydrology and hydraulics modeling has been completed for each site.

In FY23 30% designs were completed for Pole Creek, Brush Creek, Gate Creek (2x), and Grouse Creek (2x) under contract #90940.

In FY24 Final designs for Pole Creek were completed under contract #93299.

Estimated BPA Metrics:

This project will primarily benefit steelhead (Oncorhynchus mykiss) and bull trout (Salvelinus confluentus), and to a lesser degree may benefit spring chinook (Oncorhynchus tshawytscha) as well. Each of the seven tributaries proposed contain intrinsic potential (IP) for Steelhead, and six contain IP for bull trout. Cumulatively, the replacement of all proposed barriers would result in improved access to 6.02 miles of IP for steelhead and 4.84 miles for bull trout. Cramer Fish Science (2019) reports that the correction of the fish passage barriers identified in this proposal on Gate Creek, Grouse Creek, Twin Creek, Goose Creek, and Deep Creek would result in a gain of 6.08 miles of fish habitat. O.mykiss have been confirmed in all of the tributaries identified in this proposal (Cramer Fish Science 2019; T.Hillman, personal comms; US Forest Service fish data), except for Pole Creek where they are likely to be present. A 2002 survey documented steelhead redds in the lower 1.6 Rkm of Twin Creek (US Forest Service fish data). Juvenile spring chinook have been documented in the lower reaches of Brush Creek (T.Hllman, personal comms) and have a presumed presence in Goose Creek (WDFW fish distribution layer) up to the first culvert barrier. Quantile regression forest capacity estimates (QRF), based on CHaMP monitoring sites, suggest habitat capacity for redds, summer rearing, and winter rearing for both steelhead and spring chinook in the tributaries identified in this proposal (UCSRB webmap).

Project Prioritization:

This project occurs in a Major Spawning area for spring Chinook and steelhead. The project addresses the limiting factor of fish passage in the Chiwawa River and provides additional benefits to other limiting factors. Step 1 of the recent prioritization effort (2020) identifies the Lower Chiwawa AU as a Tier 1 restoration priority for spring chinook, and a Tier 2 restoration priority for steelhead and bull trout. High priority life stages in the Lower Chiwawa that will benefit from this project (from Step 2) include summer rearing and winter rearing for spring chinook and winter rearing for steelhead.

The Lower Chiwawa AU is noted in Step 2 as having limiting factors related to temperature and side channel/off-channel habitat. The goal of this project to provide improved access to thermal refuge and off-channel rearing habitat provided by tributaries, thus helping to address those limiting factors. All culverts proposed for correction in this proposal have been surveyed and identified as fish passage barriers based on WFDF protocols. The barriers have been run through the Upper Columbia Fish Passage Barrier Removal Prioritization and scored based on metrics developed by the barrier sub-group and approved by the RTT. Ten of the barriers (Brush Creek, both Gate Creek, both Twin Creek*, both Goose Creek*, and Pole Creek (*see note on scoring in summary table below)) are currently scored as Tier 3 Priorities. The Deep Creek barriers are Tier 4 priorities, scoring lower because they only benefit steelhead based on model parameters. One thing the model does not account for well is how to score barriers that are addressed as a group, where all barriers in one creek are corrected as one project, as the eventual implementation of this proposal would do. A summary table of barrier scores and notes on scoring is provided at the end of this section.

Supplemental Biological Justification/Information of Project:

The tributaries in the Lower Chiwawa identified in this proposal provide a cold-water input and refugia for ESA fish during warm months. Water temperatures are projected to continually warm over the coming decades. The NorWest Steam Temperature Model (2017) shows temperatures in the Upper Wenatchee River and Lower Chiwawa River ranging from 15.5°C to 20.8°C in 2080 (under scenario A1B).

ESA species will be seeking cold water refugia to escape these near lethal temperatures. The same NorWest model projects colder, tolerable temperatures in 2080 for all of the tributaries at the culvert locations identified in this proposal: Brush Creek 13.5°C, Gate Creek 13.59°C, Grouse Creek 12.35°C, Twin Creek 12.34°C, Pole Creek 13.37°C, Goose Creek 13.85°C, and Deep Creek 14.7°C. Increasing connectivity to cold water refugia can improve the Viable Salmonid Populations (VSP) parameters abundance, productivity and spatial structure for ESA-listed species in the Wenatchee Basin.

The tributaries in the Lower Chiwawa identified in this proposal provide important habitat for fish. The mainstem of the Lower Chiwawa is lacking in habitat features such as side channels, large wood, cover, and diverse substrate. Tributaries of the mainstem can act akin to side channels in that they provide slower, shallower water with abundant cover. These attributes are especially important for rearing fry and parr salmonids. The tributaries identified in this proposal occur within largely intact, functioning and protected sub-watersheds, and quality rearing habitat can be projected to persist into the future. Providing improved access to high quality rearing habitat can improve the VSP parameters abundance and productivity for ESA-listed species in the Wenatchee Basin.

The tributaries identified in this proposal provide genetic refuge and contributions for upper Wenatchee steelhead. O.mykiss have a highly complex and adaptable life history. McMillan, Katz and Pess (2007),documented resident male O.mykiss spawning with female anadromous steelhead in rivers on the Olympic Peninsula. A 2016 study conducted in Big Bear Creek, Idaho, “identified evidence of limited downstream gene flow [over a partial natural fall barrier], suggesting that resident [O.mykiss] fish contributed genetic material to the downstream anadromous population” (Bowersox, Wickersham, Redfield and Ackerman). Thrower et al. (2004) found that resident fish that had been isolated from anadromy for 80 years still smolted and returned to the ocean under experimental conditions. A 2013 study in the Yakima Basin, Washington, concluded that, “Basin-wide, 20% and 7% of steelhead collected in 2010 and 2011, respectively, had resident maternal life histories” (Courter et al.). These authors go on to conclude that, “Cross-life-history form production may be critical to persistence of anadromous life histories within partially anadromous salmonid populations, particularly in areas where anadromous fish abundance is low due to natural or anthropogenic influences” (ibid). Indeed, many authors have concluded that the resident life history form can be viewed as a genetic cache to be considered in steelhead conservation (Hayes et al., 2012; Holecek & Scarnecchia, 2013; McPhee et al., 2007; Van Doornik, Berejikian, et al., 2013; Van Doornik, Eddy, et al., 2013; Weigel, Connolly, & Powell, 2014). Therefore, correcting these barriers and improving the connectivity of headwaters to the ocean can improve the VSP parameter Diversity for ESA-listed steelhead in the Wenatchee Basin.

The correction of the undersized culverts that are identified in this proposal will improve the function of natural watershed processes. Undersized culverts restrict the flow of water, wood, and streambed substrate, and the associated flow of nutrients, in addition to fish movement. The design of replacement structures will allow high volume flows and associated wood and streambed substrate to pass freely through the structure and feed downstream habitat without causing backwatering, restrictions, or blockages. These blockages can cause damage to instream habitat via rapid, catastrophic erosional events. Allowing natural substrate transport and sorting to occur can potentially improve spawning conditions in these tributaries. The Lower Chiwawa River is somewhat starved of wood and diverse sediment classes. If future restoration actions in the Lower Chiwawa provide the needed structure, the natural sediment and wood input regimes of tributaries, restored by the barrier corrections identified in this proposal, would have a higher potential to remain in the system and could contribute to the long-term maintenance and functionality of engineered structures. Restoring natural watershed function can improve the VSP  parameters abundance, productivity and spatial structure for ESA-listed species in the Wenatchee Basin.

The Lower Chiwawa mainstem is one of only a few remaining strongholds for Wenatchee steelhead. The correction of the 13 fish passage barriers in this proposal will improve connectivity to cold, clean and complex habitat, addressing all four VSP parameters required for recovery, and helping to improve the likelihood of the continued survival of this ESA species.