Post-Construction Monitoring and Evaluation of Lower Whitepine Reconnection Project

Monitoring of the Lower White Pine Reconnection (LWP) Project under 14-YN-04 was carried out as a continuation of activities previously conducted under contract 11-Yaka-01 with a primary focus on post-construction S&T monitoring of use during summer/winter timeframe of the newly created off-channel habitat. The goal of our monitoring effort was to determine the extent to which the reconnection improved the use of the LWP area by ESA-listed salmonids (Spring Chinook, summer steelhead, and bull trout) as well as coho salmon. Within the project area, monitoring for target species of both juvenile and adult life stages was performed. Visual estimation of juvenile abundance via snorkel surveys and operation of two PIT tag antennas in two tributaries (Roaring Creek and Coulter Creek) were the primary means of monitoring. These methods were used in conjunction with data collected concurrently by other agencies. Estimated pre-implementation densities of both spring Chinook and summer steelhead were low in comparison to the control reaches. Summer 2017 saw a dramatic spike in abundance with LWP as paired against the control reaches but overall, there were larger number of fish within the Nason stream system due to a high adult spawner escapement in 2016. In 2019, the scale station site became an unsuitable comparison due to the changing stream morphology discussed previously.

Specifically, this project monitored 2.1 miles of instream habitat, including 1.5mi of fish surveys for adult salmonids and smolt/fry, 0.5mi of redd counts, 0.5mi of carcass counts, and monitoring of entire 2.1mi for water quality (macroinvertebrates, water temperature, dissolved oxygen, turbidity) , water quantity, habitat condition (vegetation, cover, substrate, complexity), post-project implementation, and restoration effectiveness. YNF personnel conducted snorkel surveys of the LWP and its two accompanying reference reaches between the summers of 2015 and 2019. This included nighttime surveys conducted in December and/or March, and daytime snorkels conducted in August and September. Surveys crews were composed of four to six snorkelers depending on water levels and turbidity. Each set of surveys was conducted in a two day period. Fall spawning ground surveys were conducted on Roaring Creek through fall of 2018. Surveys were conducted in conjunction with YNF’s concurrent coho spawning ground surveys. Adult redd counts were not identified and likely due to lower flows, reduced adult returns to Nason Creek as well as possible barrier with the beaver dam in LWP-1.

The results reported by this project represent findings that demonstrate there may have been an early benefit to increased access but with the beaver dam reconstruction, those benefits were short lived and a long term beaver dam maintenance/beaver relocation action might be warranted to keep access open. Monitoring of the PIT tag antennas and beaver activity have suggests that increased access to spawning habitat as a result of the project is unlikely. Although the data collected cannot support increased adult passage, it does suggest that the movement of juveniles into the LWP from Nason Creek may be more prevalent than expected early on and dropped significantly after beaver activity increased. There is a caveat in these preliminary findings is that across-year variability was not established and run forecasts and returns were significantly different between years; hence the reporting in fish/m to attempt to normalize the datasets. What was noticed was that despite the variability in fish densities within LWP, there was use during summer months primarily by spring Chinook subyearling as well as winter use for steelhead for varying age classes. This reinforces the
primary objective of providing off-channel, refuge during extreme temperature timeframes within Nason Creek, where summer temps can reach as high at 18-19C and winter temps 1-2C.

Benefits will include migratory access to spawning grounds, increased juvenile rearing and foraging opportunities, and increased accessibility to groundwater influenced habitat. ESA listed species such as spring Chinook, summer steelhead, and bull trout would likely show increased use of these areas with the hypothesis that that each species would benefit from the additional habitat provided. The Nason Creek drainage has a high potential to increase salmonid productivity and abundance; therefore, the restoration of ecosystem function in Nason Creek through increased habitat complexity is a priority for salmon recovery in the Wenatchee watershed (Upper Columbia Regional Technical Team 2008). Currently, Nason Creek is home to stable populations of spring Chinook and summer steelhead. Nason Creek is also a targeted stream of emphasis for the Mid-Columbia Coho Reintroduction Program, and historically thought to be one of the main contributors of coho salmon in the Wenatchee basin.