Hydrocarbon baseline data are needed to assess the potential impact of oil contamination from increased tanker traffic in the Strait of Juan de Fuca. Initial studies were directed to intertidal sediments, mussels and snails from two physically similar areas: Port Angeles, WA and Dungeness Bay, WA. Latest analytical techniques of solvent/slurry extraction, silica gel chromatography, and glass capillary gas chromatography were adapted for analyzing large numbers of samples. The methods apply to alkanes in the C14 - C32 range, or to aromatics from substituted benzenes through benzpyrenes. Individual hydrocarbons were determined within 20% standard error at the 10 ng/g level. Lowest hydrocarbon levels were found at Dungeness Bay, a relatively pristine area. The profile of the alkanes suggests that the Dungeness hydrocarbons arise biogenically. Hydrocarbon levels were substantially greater at Port Angeles harbor, especially adjacent to Peabody Creek. The even distribution of C14 - C22 n-alkanes from creekside sediment is consistent with know fuel oil seepage upstream. Above C22, the n-alkane pattern appears more biogenic, although the levels are high. Significant divergences between the two areas were found in the phenanthrene fluoranthene, and pyrene levels. Seventeen aromatic hydrocarbons are proposed for baseline monitoring.