The data support a study that surveyed the spatial and temporal distribution of salmon eDNA in Seattle urban creeks, Washington, 2018 - 2020. The metadata represent qPCR quantification cycle (Cq) values for Chinook salmon, coho salmon, and coastal cutthroat trout assays performed on water samples collected on specific days at specific sites on Thornton Creek, Taylor Creek, and Mapes Creek, which are tributaries of Lake Washington within Seattle city limits. The metadata also includes latitude and longitude for each site and Y-intercept and slope for each assay run.