The Asotin Creek subbasin is comprised of 83,850 hectares in Asotin and Garfield Counties in Washington, and includes Asotin Creek, Tenmile Creek, Couse Creek, Alpowa Creek, and tributaries. The Asotin Creek salmon population, as named by the NOAA Fisheries Technical Recovery Team (TRT), includes Asotin Creek, George Creek, Tenmile Creek, Couse Creek, and Alpowa Creek. The Asotin Creek mainstem is comprised of several major tributaries, including the North Fork, South Fork, Charlie Creek, and George Creek. This research, monitoring and evaluation (RM&E) project provides estimates of abundance, productivity, survival rates, and temporal and spatial distribution of ESA-listed summer steelhead, Oncorhynchus mykiss, for the Asotin Creek steelhead population.

Substantial efforts have been made to assess salmonid populations in the subbasin since 1984 (M. Schuck, pers. comm.). The Washington Department of Fish and Wildlife (WDFW) designated the Asotin Creek subbasin a wild steelhead refuge in 1997, and no hatchery fish have been planted in Asotin Creek since 1998.

This project began in 2004, with the monitoring of juvenile salmonids in the Asotin Creek mainstem. As of 2015, the project has expanded over the years, to operate 4 adult traps on adjacent Snake River tributaries and the mainstem of Asotin Creek. The juvenile population emigrating from Asotin Creek is estimated using a rotary screw (smolt) trap, currently located at RKM 3.0. As of November 2018, this project has collected fourteen years of adult steelhead data and fifteen years of juvenile steelhead data. The data collected describes a persistent steelhead population, which is variably affected by stray hatchery steelhead, which remains large for a subbasin of its size, especially when compared to other steelhead populations in the Columbia Basin.

The goal of this project is to assess the status of anadromous salmonid populations in the Asotin Creek subbasin and adjacent Snake River tributaries. This research, monitoring and evaluation project provides estimates of abundance, productivity, survival rates, and temporal and spatial distribution of ESA-listed species: Summer steelhead Oncorhynchus mykiss and spring Chinook salmon O. tshawytscha.

Asotin Creek is a scientifically sound reference stream and -- given the lack of un-supplemented reference streams for supplementation effectiveness monitoring -- has one of the few steelhead populations that can provide reference data for understanding wild steelhead biology. Using the Asotin Creek Salmon Population Assessment project to provide reference data for evaluating the effects of steelhead supplementation as a recovery tool in the Columbia Basin is supported by the co-managers and associated fish management agencies: NOAA Fisheries, the WDFW, Snake River Salmon Recovery Board, the Nez Perce Indian Tribe, Oregon Department of Fish & Wildlife, Wells Hatchery Committee, and the Washington State Governors' Salmon Recovery Office (GRSO).

The objectives for this project are:
Objective 1: Estimate escapement of wild and hatchery steelhead and Chinook salmon into Asotin Creek.
Objective 2: Estimate spawner abundance in Asotin Creek, George Creek, Alpowa Creek, Tenmile Creek.and Couse Creek, if possible, annually.
Objective 3: Document juvenile steelhead life history patterns, survival rates and estimate juvenile emigrant production in Asotin Creek.
Objective 4: Collect DNA samples for future genetic characterization of focal species.
Objective 5: Report and disseminate Asotin Creek salmonid assessment data.

To meet these objectives, we plan to operating 5 adult steelhead weirs and continue to operate the juvenile smolt trap. The juvenile smolt trap is now located at RKM 3.0. Weirs will be installed on Asotin, Alpowa, George and Tenmile Creeks. A full understanding of the abundance and productivity of steelhead in those tributaries is necessary to adequately understand the status of the Asotin Creek steelhead population. This project has specifically collected information from Tenmile, Couse and Alpowa Creeks, while another BPA funded project (#2010-028-00) has assessed adult steelhead returns in Almota Creek (Gembala and Trump 2016.)

A secondary aspect of this project is monitoring the response of steelhead and the other salmonid populations present to the habitat restoration activities occurring throughout the Asotin Creek subbasin. This translates into increased coordination and collaboration with various disciplines not only within WDFW, but also with the other cooperators within the subbasin as habitat and population response is documented as part of the Intensively Monitored Watershed (IMW) project.