Towards a Stable Future: A Design Proposal for Cerrito Creek in Blake Garden, Kensington, California

An upstream reach of Cerrito Creek, in Contra Costa County, California runs through Blake Garden, a 10.5-acre demonstration garden owned by the University of California, Berkeley (Fig 1 & 2). Th is study focuses on a 420- foot reach near the top of the garden that has a severely incised and undercut channel, undersized and deteriorating culverts, and failed bank armoring. In the spring of 2010 for LA222: Hydrology for Planners, the authors of this paper analyzed the hydrology of the watershed above the reach, in order to understand the fl ows that are likely causing incision, conducted extensive fi eld surveys, and modeled fl ow in the creek. Continuing with last semester’s work, we conducted a detailed facies map, and identifi ed constraints and opportunities along the stream channel. Permanent monuments were placed on the site, and accurate mapping of the reach and cross-sections was generated. Based on our cumulative understanding of the site, we propose a stream design that will arrest incision and bank failure while allowing the 100-year fl ood to be conveyed through the channel by either reducing velocity below scouring or by protecting the banks. We achieve this by creating step-pool sequences in the actively incising sections, connecting the channel to a floodplain where possible, and proposing bank protection where the channel is more constricted. Th e design follows our goals of enhancing wildlife habitat, and serving as an attractive design element and educational focus within Blake Garden