For comparison of PCB concentrations in sediment collected from different locations in the Bay Area, data were evaluated from studies that used similar methods of collection, analysis, and quality assurance. These studies include the San Francisco Estuary Regional Monitoring Program for Trace Substances (RMP), the Bay Protection Toxic Cleanup Program (BPTCP), which included a Pilot Regional Monitoring Program, a study of contamination in San Leandro Bay, and a study of PCB and mercury contamination in stormwater conveyance systems in the watersheds of the San Francisco Estuary. The studies cited in this dataset were not conducted simotaneouly and each have their own timeline. As a group, the studies took place from 1991 - 2000.