Post-project appraisal of the Sausal Creek restoration project, Oakland, California

Sausal Creek originates in the Oakland Hills of California, runs through the city of Oakland, and terminates at the San Francisco Bay. The lower half of the riparian corridor is channelized or culverted and the upper half is natural and free flowing. Dimond Canyon Park is located in this transition area and the steep banks experience erosion and landsliding. The proximity of the corridor to development makes it a focus of attention. In the 1930’s, the Works Progress Administration installed extensive concrete and steel structures in the creek to control erosion and stabilize the banks. In 2001, the City of Oakland, the California Coastal Conservancy, and the Alameda County Flood Control and Water Conservation District sponsored the restoration of an 825-foot reach of the creek with the help of the Friends of Sausal Creek. The project’s stated objectives were to remove six in-stream structures, improve water quality, stabilize the channel and banks, control erosion, improve access, and additionally to restore hydrologic function, sediment transport, native vegetation, and habitat for aquatic and terrestrial species. By 2002, the structures were removed from the channel, six rock weirs installed, 20,000 plants planted, bank stabilization installed, and 600 feet of the channel realigned and regraded.We conducted a post-project appraisal (PPA), based on water quality, aquatic insect, and vegetation monitoring data collected by the Friends of Sausal Creek. These data indicated no change in water quality or aquatic insects since the project. However, percent cover of vegetation increased from zero to 50 percent in the first 18 months of the project. FoSC found that 74% of the vegetation in the riparian corridor is native and using the Simpson’s Diversity Index, found that diversity has dramatically increased since the restoration. We surveyed nine cross-sections and the long profile of the restored channel. We compared our data to pre-project design information from Wolfe Mason and Associates and the as-built data from the Restoration Design Group and detected no changes in the channel. The rock weirs appeared to successfully create riffles and deep pools. We conducted a qualitative community survey and found that the trail is highly used by park visitors who are excited about the restoration. However, we found evidence that dogs and people are eroding the banks in accessing the creek, which could cause future failure. We recommend evaluation of sediment transport and hydrologic function, continued monitoring, implementation of dog management guidelines, permanent survey markers, and continued invasive plant removal