City of Seattle, Seattle Public Utilities, Annual Bull Trout Redd Surveys in Tributaries to Chester Morse Lake 1996-current, Cedar River Municipal Watershed, King County, WA

These data were collected during weekly annual redd surveys conducted by Seattle Public Utilities (SPU) in the Cedar River Municipal Watershed (CRMW), 1996 - current. Annual weekly bull trout redd surveys funded through the CRMW Habitat Conservation Plan (HCP) began in 2000 and ended in 2011 spawning year. To reinstate a monitoring program for the population, redd surveys in the most heavily used habitats by bull trout (termed the Core Zone), were opportunistically conducted in 2018. Weekly annual surveys in most of the Core Zone were reinstated in 2019. Approximately 77% of all redds observed 2000 - 2011 would have been observed during those years using the 2019 - 2022 spatial survey extent (SPU data on file). In 2023, the spatial and temporal coverage of surveys were on par with historical coverage, i.e., approximately 100% of all redds observed 2000 - 2011 would have been observed using the 2023 spatial survey extent.

Information on redd location is used primarily to enable derivation of redd elevations. Redd elevation is required to estimate potential impacts to the spawning population and incubating embryos caused by reservoir inundation of stream spawning habitat after the spawning period during fall through spring. Redd weekly timing information is critical to accurately represent whether embryos remain in the gravel and are vulnerable to impacts of reservoir inundation as the reservoir is refilled starting in early spring. It is also vitally important that SPU understand timing and abundance of redds beyond the inundation zone to enable understanding of the overall impact to the population.