Design of Salinity Intrusion Barrier

Client: US Bureau of Reclamation, Mid-Pacific Region

The US Bureau of Reclamation (Reclamation) and the California Department of Water Resources (DWR) propose to implement the Franks Tract Project to improve water quality and fisheries conditions in the Sacramento–San Joaquin Delta (Delta). Reclamation and DWR are planning to install operable gates on Threemile Slough (photo at right) to reduce seawater intrusion and positively influence movement of fish species of concern to areas that provide favorable habitat.

WRE was the prime contractor responsible for the feasibility-level design, engineering, and cost estimating for the operable gates. After WRE evaluated a number of options, Reclamation and DWR decided to implement a 550-foot- wide, 30-foot-tall removable barrier composed of ten bottom-hinged gates lifted and lowered by hydraulic cylinders.

WRE provided hydraulic and geomorphologic analyses as well as structural, mechanical, electrical, and controls/instrumentation design for the various project components. The project will include a navigation lock to allow boat passage when the barrier is up, as well as levee improvements and removable floating booms to protect the gates. When built, the proposed $260M structure will be the largest of its kind in the United States.