Forterra, in partnership with Pierce County, the Puyallup Tribe of Indians, and the South Puget Sound Salmon Group, commissioned Anchor QEA to develop a Conceptual design (or updated feasibility study) for the removal of Chambers Creek Dam and the restoration of the estuary of Chambers Bay (Project), with a primary focus on restoring nearshore processes of the estuary including tidal hydrology, freshwater inflow, sediment erosion and accretion, channel morphology, detrital inputs, and restoration or enhancement of the tidal marsh and riparian vegetation communities. Removal of the Chambers Creek Dam and restoration of the estuary would benefit Chambers Creek coho salmon, chum salmon, steelhead, and cutthroat trout, as well as non-natal salmon, trout, and forage fish populations from all over Puget Sound utilizing South Sound for rearing, foraging, and growth before leaving Puget Sound to make their ocean migrations. The primary focus of this conceptual design / feasibility study includes identifying and assessing the range of technical elements associated with the eventual removal of the Chambers Creek Dam, defining design criteria, and evaluating the upstream and downstream benefits and risks associated with restoring a natural hydrologic and sediment regime to the estuary. The study describes the costs, benefits, and risks of a range of alternatives as well as actions to mitigate the impacts of the dam if left in place. Dam removal would, by necessity, require the replacement of the Chambers Creek Road Bridge. This structure is at the end of its functional life and will need to be replaced soon, whether or not the dam is removed. Any new bridge should be designed to accommodate future dam removal, since the am no longer serves its intended purpose, is aging, and is not designed to withstand tidal exchange associated with sea level rise. The cost of road, utility, and bridge realignment are among the highest cost elements of the Project and are a focus of the different alternatives, but future replacement of the bridge will inevitably include many of these costs, with or without dam removal. The alternatives each have outcomes that could affect the following: • The impact of dam removal on sediment movement, deposition, and biologically available contamination • The impact of dam removal on habitats and habitat forming processes • The safety of drivers and park users • The future use of properties in and adjacent to the bay Any significant future project would require landowner permission in order to move forward. The projects contemplated in this report would also require extensive environmental review and permitting. The Project footprint is likely to include three local jurisdictions (the Town of Steilacoom, University Place, and Pierce County) and would impact resources of concern to tribal, federal, and state agencies. This report identifies both a preferred alternative for near-term action and a strategy to continue restoration efforts and expand the Project in later phases. The preferred alternative involves removing the dam, replacing the bridge in a location near the existing bridge, and restoring habitat in the bay and riparian areas of the lower creek. This report has been updated in 2022 from the original version, which was finalized in April of 2019 (titled the Chambers Creek Dam Removal Project Feasibility Study). The primary purpose of this update is to reflect minor changes to the preferred alternative based on developing project conditions. These changes include Pierce County beginning the process for a type, size, and location study for the Chambers Creek Bridge. This study is limited to locations near and similar to those of the existing bridge. Earlier drafts of this study included more radical realignment options that, based on the findings of those earlier drafts, are not being carried forward at this time. The Project partners have also had continuing discussions with a party interested in the redevelopment of the former Abitibi paper mill site. This has created an opportunity for a partnership that includes work by others on the mill site some of which has been identified in some of the alternatives described in this report. This report also includes a more detailed assessment of the use of engineered log jams in the estuary, downstream of the dam. The purpose of these structures would be to manage the deposition of sediment by lowering water velocities where deposition of sediment from above the dam is desirable and limiting it near the Chambers Bay Marine and Storage marina (the marina) where deposition is problematic. These changes have been added to the evaluation and a new alternative (Alternative 1-1) has been added to reflect the current state of the Project. Additionally, this updated 2022 report now incorporates several follow-up efforts that were conducted after the 2019 Feasibility Study. These include the 2018 Sediment Sampling and Analysis Plan (Appendix A, Contract Amendment 1), and the 2021 Implement Supplemental Sediment Sampling and Analysis Plan (Appendix A, Contract Amendment 2). The appendices are available to RCO upon request.