Based on historical commercial landings and habitat availability, it has been estimated that between 0.5-1 million chum salmon returned annually to the Lower Columbia River (LCR) and its tributaries (Johnson et al. 1997).  A combination of several factors (loss & degradation of spawning and rearing habitats, changes to estuary ecology and habitat, altered mainstem and tributary hydrology, and harvest) resulted in a significant decline in chum salmon abundance beginning in the 1940s.  The decline continued through the 1950s even after the harvest pressure was removed.  In 1999, LCR chum salmon populations were listed as threatened under the auspices of the Endangered Species Act.  Of the 17 historic LCR chum salmon populations, 90% are considered extirpated or nearly so.  The Lewis population of chum salmon falls into the “nearly so” group.  This population is at high risk as a result of low population size, low productivity due to loss of preferred/ needed spawning habitat, low diversity, and limited temporal and spatial distribution.  

Recent adult returns of LCR chum salmon to the Lewis Basin are estimated to be less than 25-50 adults annually.  This compares to estimated historical return sizes between 120,000 and 300,000 adults (LCFRB North Fork Lewis Subbasin Plan, 2010).  The Lewis, Cowlitz and Sandy chum salmon populations are identified as the primary recovery populations within the Cascade strata of the LCR chum salmon ESU (NMFS 2013).  Recovery plan goals include increasing the Lewis basin population viability from low (current state) to high, decreasing population risk from high (current state) to low, and reaching a target adult abundance level of 1,300 annually.  De-listing requires at least two primary populations within each of the ESUs strata be “recovered”.  Due to the low smolt-to-adult survival rates that LCR chum salmon experience, significant increases in freshwater productivity in this population will be necessary to achieve recovery plan goals.  

Spawning channels have proven to be an effective tool to increase freshwater productivity (egg-to-fry survival rate) of chum salmon populations.  Egg-to-fry survival rates in similarly constructed chum salmon spawning channels in the LCR have documented average egg-to-fry survival rates in the 50-55% range (Hillson and Ronne, 2016) compared to similarly estimated egg-to-fry survival rates from run-of-the-river spawners which can vary from near zero to 22% depending on the year (Salo 1991).  Adults who utilize the spawning channel will realize a significant boost in productivity compared to adults spawning in the mainstem Lewis River.

Section 3.2.4 (page 3-31) of the LCR salmon recovery plan states "Chum habitats have been reduced by 75% or more for the majority of the populations by changes or loss of low elevation reaches and off-channel areas due to channel stabilization, loss of floodplain connectivity and function, and sedimentation due to land use activities throughout the entire watershed." (LCFRB 2010).  This statement is especially true in the areas of the Lewis River basin that chum salmon historically utilized.  Additionally, there is a hydropower/flow regulation component on the North Fork Lewis River further reducing the likelihood of natural habitat processes creating the productive side- and off-channel spawning habitat types that chum salmon need within the basin.

This project is in alignment with WDFWs regional chum salmon recovery plan objectives which are to  1) protect, restore, or create protected high quality off-main channel spawning habitats to increase fresh-water productivity (egg-to-fry survival), 2) supplement existing populations using a genetically appropriate donor stock to jumpstart usage of the new habitat and begin local adaptation of donor stock, 3) monitor adult and juvenile outmigrant monitoring at the spawning channel to estimate egg-to-fry survival rates by marking all fish produced via Parental Based Tagging (PBT; Anderson and Garza 2005) so that channel-origin adults can be identified, and 4) adaptively manage the project by using results of prior chum salmon monitoring activities within, and from outside, the basin to inform future decisions.

The Eagle Island chum salmon spawning channel (spawning channel) project has a long history.  In 2010, a scoping project, funded by the Bonneville Power Administration (BPA) through the LCR chum salmon BiOp project (2008-710-00), was initiated to identify potential chum salmon spawning channel sites within the East Fork Lewis and North Fork Lewis river basins.  Over the course of several years, multiple sites in both basins were monitored and evaluated.  At the end of this process, it was determined that the Eagle Island site had the highest potential for a successful spawning channel (Lewis Basin Groundwater Investigations and Spawning Channel Design chapter).  A mixture of funding sources (BPA, the Odessa Water Withdrawal mitigation fund, and WA State) have been used to complete the spawning channel project up to the construction phase.  We have final designs and are in the process of securing all the necessary State, local, and Federal construction permits including ESA coverage and a completed cultural resources review (106 permit).  A copy of the completed design report and permit drawings have been attached in cbfish.org.  In the fall of 2018, the access road to the site was improved and approximately $450K of construction materials (rock, spawning gravel, and logs), purchased through BPA project 2008-710-00, were moved on-site and the out-of-water section of the spawning channels alignment was cleared.  Our plan is to complete construction of the spawning channel in the late spring and summer of 2024.  As of the date that this proposal was submitted, the intent is to use staff from WDFWs Construction and Asset Management Program (CAMP) to accomplish the construction of the spawning channel.

The overall goal of the Eagle Island spawning channel project is to create protected high quality off-main channel spawning habitat that can support at least 500 spawner pairs and be expected to reliably provide egg-to-fry survival rates of ~50% or greater annually.  Highly productive chum salmon spawning and incubation habitat is critical for the recovery of this species within the Lewis Basin due to the low smolt-to-adult survival rates that LCR chum salmon experience.  As a result of the increased productivity within the population, abundance is expected to increase thereby increasing diversity and species spatial and temporal distribution, which will reduce the extinction risk to the population.  A long-term goal of the WDFWs regional chum salmon recovery strategy is to use a healthy and stable Lewis population as a donor stock for reintroduction/enhancement programs in other Cascade strata populations.