This technical memorandum describes the current channel and riparian conditions and their drivers in the Petaluma River watershed and adjacent drainages (the Petaluma Operational Landscape Unit). We combine spatial analysis of current riparian zone characteristics with a discussion of the historical context, the key drivers that define current conditions, and the ecological and hydrogeomorphic functions of the riparian zone in the watershed. This assessment draws from scientific literature, existing reports, and regional datasets. A standard 100-foot buffer around mapped stream lines was used to define the riparian zone, and riparian vegetation patterns within this zone was the focus of a general description of current channel and riparian areas across the watershed. This document synthesizes existing information to describe the broader-scale regional drivers of channel and riparian characteristics. It includes a conceptual overview of the ecological functions supported by riparian areas across the watershed and details the key local drivers and riparian characteristics of the three major subwatersheds in the study area.

This document is a precursor to the technical memorandum: Future Climate Impacts to Riparian Condition & Function in the Petaluma River Watershed.