San Pablo Creek drains 42 square miles, debouching into the San Pablo Bay in Richmond, California. In 1919, East Bay Municipal Utility District built a dam in the mid-watershed. The Dam rarely releases water, so the reach downstream (lower San Pablo Creek) has a distinct hydrology driven by runoff from the unregulated, lower, 11.2 square-mile drainage area. Perhaps because flooding is infrequent, and because land-use policies and management have not historically considered low-order channels and their riparian habitat, regulating agencies have spent little time collecting baseline information on the creek. This study seeks to gather such baseline information. The specific questions this study addresses are: 1) What are the key ecological and geomorphic transition zones along the Lower San Pablo Creek? 2) What are the geomorphic, hydrologic, and vegetation characteristics in each of these zones? and 3) What are the discharge estimates for cross-sections in each of these zones?

The results of our study indicate that there are five distinct zones along lower San Pablo Creek: the Upper Alluvial Valley, the Lower Alluvial Valley, the Upper Alluvial Fan, the Wildcat-San Pablo Creeks Alluvial Fan, and the Tidal Flats zones. Results from discharge estimates indicate a wide variance of discharge rates between Rantz, Haltiner, and Wannanen-Crippen methods. A high dominance of non-native vegetation and significant incision in the upper cross-sections indicates potential for future restoration efforts.

The San Pablo Creek Watershed is a large and geographically diverse stream located East of the San Francisco Bay. San Pablo Creek historically provided habitat for an abundant population of steelhead trout, a federally listed threatened species. However, in 1919, the East Bay Municipal Utility District (EBMUD) constructed a dam and reservoir on San Pablo Creek. Since the 1950’s, residents and regulators have observed a decline in the abundance of anadromous fish. Our study assesses San Pablo Creek’s current viability for anadromous fish, by examining the input of water from perennial tributaries of San Pablo Creek and the mainstem’s habitat characteristics. By analyzing flow patterns and features including pool-riffle sequences and embeddedness, we determined that San Pablo Creek provides adequate rearing habitat for steelhead trout, but limited spawning habitat.