SWAMP Tissue Summary Results

This dataset provides annual summary statistics of contaminant concentrations in aquatic organism tissue samples collected by the Surface Water Ambient Monitoring Program (SWAMP). The data are derived from raw individual and composite tissue sample results reported to the California Environmental Data Exchange Network (CEDEN) and are used to support environmental assessments, management reporting, and public transparency. Each record represents a unique combination of monitoring station, analyte, species, sample type (individual or composite), and year. The dataset includes multiple types of annual averages to reflect different biological and analytical considerations. Composite Samples: A straight arithmetic average is calculated for each composite group per year. Individual Samples: Three types of annual averages are calculated: * Average of Individuals – Mean of all individual sample results. * Average of Individuals ≥305 mm – Mean of individual samples where the organism’s total length is greater than or equal to 305 mm. * Average of 350 mm Length-Adjusted – A modeled average that adjusts individual sample results to a standardized organism length of 350 mm. Each of these averages may also be further broken down by location codes (e.g., L1, L2), which represent sub-locations within a monitoring station. These are captured in the ResultType column. Additional fields such as the number of non-detects (ND_in_Avg), total number of samples (N_in_Avg), and the most recent sample collection date (LastSampleDate) provide transparency into how each average was calculated. They also support the display and filtering of data in the [SWAMP Data Dashboard](https://gispublic.waterboards.ca.gov/swamp-data/).