River-Lab

We conducted an appraisal of an urban creek daylighting project in San Pablo, California, to evaluate the ecological integrity of the restoration, understand if the project achieved its goals, and recommend planning guidelines for future projects. This 2013 project in John Herbert Davis Park daylit a 550 foot culverted section of Wildcat Creek, with objectives to improve flood control, create riparian and fish habitat, and expand trail access. We analyzed current project conditions by surveying vegetation at 8 transects, surveying vegetation by planting section, conducting 2 bird counts, mapping the creek bed and vegetation cover, and recapturing 15 photopoints. We compared results with initial plans and monitoring, which continued for 5 years.We found that the project created a riparian vegetation community with habitat supporting bird abundance, density, species richness, and diversity. Willow trees make up 80% of the overstory plants, as a result of an initial 560 willows planted. Overstory vegetation developed an almost fully closed canopy over the creek; we found 95% canopy cover. Little of the planted understory has survived, which we attribute to shade, human use, and competition from invasives. Invasive species dominated the understory composition, including Algerian ivy, veldt grass, and kikuyu grass. We found the surface cover consists primarily of live woody, non-woody vegetation, and vegetation litter. We did not observe streambed conditions for fish habitat given the seasonal lack of water.The project succeeded in increasing longitudinal connectivity through robust initial monitoring, extension of Wildcat Creek Trail, providing riparian habitat to support bird life, and constructing a channel and floodplain with an 100 year flood capacity. However, the project failed in overgrowth of vegetation, lack of continued monitoring funds, and death of the planted understory, in conjunction with invasive encroachment. Canopy overgrowth has additionally facilitated lack of bank-to-bank visibility, thereby encouraging encampments and dumping, resulting in decreased safety.At the site, we recommend thinning willow density and management for invasives. We also recommend appending guidelines for project planning and monitoring of urban creek restorations into the next version of the Wildcat Creek Restoration Action Plan for the City of San Pablo. We propose the following potential guidelines: centering principles of longitudinal and lateral connectivity, considering site-specific opportunities and constraints; selecting planting palettes appropriate for long term public and ecological use; planning for long-term physical, ecological, and social monitoring; and creating quantitative objectives prior to project implementation.