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.

This project was originally proposed and funded under the 13 Chiwawa Barriers Design - Contract # 88609. The following provides Supplemental Biological Justification/Information for the correction of all 13 barriers, including the two for this project on Goose Creek:

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.