Santa Monica Mountains BPG Monitoring with Topanga Creek Life Cycle Monitoring Station FY23/24

This study is a continuation of long-term monitoring efforts initiated in 2001 by the Resource Conservation District of the Santa Monica Mountains (RCDSMM) to capture the salmonid Viable Salmonid Population parameters (abundance, productivity, spatial distribution, and diversity) of southern California steelhead (Oncorhynchus mykiss) within the Santa Monica Mountains. During Fiscal Year 2023-2024, monitoring conducted by CDFW continued and expanded this long-term dataset throughout the Santa Monica Mountains Biogeographic Population Group (BPG) following the recommended sampling structure provided in CA Fish Bulletin 182 via a combination of a life cycle monitoring (LCM) station within Topanga Creek and redd surveys throughout the BPG. Topanga Creek was selected as the site of the LCM due to its designation as a high priority (core 1) watershed for steelhead recovery by the National Marine Fisheries Service and the presence of high-quality O. mykiss summer refugia habitat.

The NMFS Recovery Plan requires a set population level be reached in each of the five Biogeographic Population Groups (BPG) within the Southern Steelhead Distinct Population Segment in order to de-list the species. The only way to determine what the current steelhead population status is and whether recovery efforts are working is though the establishment of a large-scale monitoring program. Without a long-term monitoring program, delisting by NMFS will not be possible.