Urban Stream Success Story After Decades of Restoration 

HDR was retained by the San Francisco Public Utilities Commission via sub-contract to AECOM to develop fish passage and screening improvements at their 31-foot-tall Alameda Creek Diversion Dam. Constructed in 1931, the Diversion Dam is in a remote, pristine watershed that had been minimally disturbed since the initial construction.  

As part of this project, we were responsible for developing and evaluating potentially feasible alternatives to provide safe and effective upstream and downstream fish passage while also developing a screening and diversion strategy that excluded fish from being entrained and transported to the Calaveras Reservoir.   

During the feasibility phase, we formulated alternatives, facilitated design and brainstorming charrettes, developed conceptual designs and associated project costs, and evaluated alternatives to measure project trade-offs to assist SFPUC in the selection of a preferred alternative. The vision and collaborative efforts of SFPUC, agency stakeholders and engineers, fisheries scientists and construction professionals resulted in the decision to proceed with fish passage improvements and a final selection for design and construction.  

HDR remained the lead designer in all hydraulic, fisheries, mechanical, electrical, and instrumentation and control disciplines during the design phase of the project. This phase was influenced by several challenging multidisciplinary factors that required consideration. 

First was the facility’s location five miles into sensitive wilderness with limited access and no service-based electrical power. To solve this the project was designed to function off-grid with both photovoltaic panels, battery backup storage and standby propane-fueled generators with a 2-week fuel storage capacity. 

Another challenge was no direct access to the entrance of the creek’s diversion tunnel on the left bank. We developed a cross-channel conveyance structure that conveyed flow from the fish screens located on the right bank back underneath the creek channel to the tunnel entrance. Alameda Creek exhibits very flashy hydrologic conditions with high levels of bedload, turbidity and debris and, therefore, the design relies heavily on a system of debris and sediment management including custom floating debris booms, coarse debris racks, debris raking equipment, and a system of primary and secondary sluice gates that are used to transport accumulated sediment in the forebay downstream through the diversion dam.  

Lastly, both a narrowband and broadband very-small-aperture terminal communication system was provided that enabled the project to be monitored, controlled and operated via supervisory control and data acquisition. 

Our work continued through engineering services in support of the construction phase of the project. At completion, these efforts led to a facility that is expected to help provide for a run of steelhead in Alameda Creek for the first time in nearly a century.