Projects & Programs
Chinook River Restoration Project, Washington
The Chinook River flows into the Columbia River five miles upstream from the Pacific Ocean. The project area is located at the mouth of the Chinook River and consists of approximately 1,050 acres of estuarine and riparian wetlands surrounding a complex network of tidal channels. Historically, the Chinook River supported populations of five anadromous salmonid species, and its estuary is an important rearing habitat for juvenile salmonids from the Columbia River basin. The reduction in species abundance from historic levels is attributed to elimination of the tidal action since the construction of a tide-gate at the mouth of the Chinook River in the 1920s. The objective of the Chinook River Restoration Project is to recover the natural estuarine and riparian wetlands habitat by restoring tidal flows through the study area.
PNNL provided water resources modeling services to Ducks Unlimited (DU) and directed civil engineering and surveying tasks. DU relied on PNNL’s model simulations to evaluate the feasibility of proposed restoration actions. PNNL collected the required data to develop predictive hydrologic and hydrodynamic models of the Chinook River estuary. The calibrated models are being applied for the proposed alternate configurations to predict the flows, velocities and water surface elevations to help identify the best option for the restoration project. The alternatives simulated include removal of the existing tide-gate under Highway 101, filling existing drainage ditches and channels, restoring tidal swales, reforesting riparian areas and constructing a new levee with tide-gates to protect adjacent landowners. The proposed restoration actions are expected to provide several long-term benefits for salmon. The removal of juvenile and adult fish passage barriers would improve productivity due to availability of higher quality habitat. The re-establishment of natural estuary flushing patterns would improve water quality. The model results will be used to address specific questions such as the ability to provide a fully functional tidal habitat, the ability to move flood water out and salinity intrusion.
Project Highlights:
- The Hydrologic model HEC-HMS and three-dimensional hydrodynamic model RMA-10 were calibrated using field data
- The hydrodynamic model application showed varying degrees of the potential for flooding with various alternatives
- The hydrodynamic model was used to design an alternative that provided adequate flood protection and achieved tidal marsh restoration goals (water levels, salinity penetration and velocities).