SITE DESCRIPTION
This project footprint is located within middle reaches of the Willamette Valley at the Albany Oxbow Lakes between the cities of Albany and Millersburg in Linn County, Oregon (RM 116).Past land use and development activities at the project site have resulted in impaired water quality conditions and reduced hydrologic connectivity between the Willamette River, Cox Creek, Truax Creek, Murder Creek, a series of oxbow lakes, and the adjacent floodplain. Historically, the Willamette River upstream from Corvallis was characterized by a multi-thread anastomosing channel. Downstream from Albany, the river plan form was characterized by a single thread or simpler channel morphology relative to the Upper Willamette River. Wallick et al. (2014) provides a description of the river corridor and the historical and contemporary influences on the river and floodplain.

Past industrial land uses have significantly altered the floodplain along this stretch of the Willamette River leading to inhibited fish passages and disconnection of floodplain hydrology. Berms constructed to improve utility of the site for industrial purposes prevent floodplain inundation in high flows, and can cause fish entrapment in subsequent low flows.

The river corridor in the project reach includes numerous oxbow lakes, side channels, and dynamic floodplain habitats. Although this reach of the Willamette River remains connected with the historical floodplain, the river is heavily influenced by historical land uses, channel armoring, and hydro-regulation by the Willamette Project. Historical riparian communities have been replaced by agriculture and gravel extraction. Stone revetments armor outside meander bends and have diminished lateral channel migration. Hydroregulation has reduced peak flows and sediment delivery to the river. With lower annual peak flows, riparian vegetation has stabilized formerly transient gravel bars and lead to channel narrowing. Road fills and crossings for industrial and agricultural development purposes have bisected tributary and floodplain channels, limiting the movement of native fish during important periods of their life histories, including winter and summer rearing when their preferred habitat is limited in this reach of the Willamette River. Floodplain berms constructed for agricultural, recreational, or industrial purposes have also limited fish access to portions of the floodplain that are important refugia areas for native fish during high flows. When these berms are overtopped during elevated flow events, fish may become stranded in low areas behind berms as flood flows recede back to the main channel. Additionally, these berms limit the delivery of macro-detrital inputs from the floodplain to the river channel that help drive primary production and food web dynamics.

The project will improve floodplain connectivity and fish habitat function through the re-establishment of normative hydrologic patterns. This is done through the removal berms in several locations to allow flow into the floodplain area within the oxbow lakes and to redistribute berm materials within the existing floodplain complex in a way that does not impede or significantly alter flows. Removal of the berms will increase floodplain inundation during high flows allowing for both greater hydrologic connectivity and improved access to floodplain habitat for migratory fish. In conjunction with fish passage improvements on 3 road crossings that will occur within the project area, this project will increase habitat connectivity and reduce the risk of fish entrapment. Given the probability of higher annual temperatures and increased flashiness within Western Oregon hydrologic systems under a changing climate, improving access to and quality of migratory and rearing habitat will contribute to the survival of anadromous fish on a year to year basis.

In general, climate change in the Pacific Northwest west of the Cascade Mountains is predicted to result in higher average annual temperatures, with more summer extreme heat events and generally higher winter low temperatures. Additionally, reduced summer precipitation and increased winter precipitation are broadly expected across the Western PNW resulting in stream systems increasingly being characterized as flashy. Intermittent high flows will increase the importance of rearing and migratory habitat such as the Albany Oxbows. Increased air temperatures resulting in increased water temperatures within the oxbow lakes threaten the capacity for the project area to provide refugia. Additionally, the potential for entrapment due to passage barriers and the berms also threaten Willamette River Winter Steelhead.

Funds from BPA will be used to build off completed feasibility and design phases and contribute to necessary surveys and investigations to finalize design package and construction-ready bid package for successful implementation. Resources will also be dedicated to secure authorizations from local, state, and federal regulatory community. Funds will also be used to leverage additional funding to cost-share construction phase of the project that is slated for 2026.  Partners for this project include The Calapooia Watershed Council, Oregon Watershed Enhancement Board, River Design Group, The Oregon Department of Fish and Wildlife, International Paper Company, and the City of Albany.