Publication Summary

Contaminated soil and sediments from upper and lower segments of Little Squalicum Creek were evaluated in accordance with applicable regulations WAC 173-340 and WAC 173-204 for determining whether they present a threat to human health and the environment. Sediment samples were tested for toxicity using amphipod (10-day Hyalella), midge (20-day Chironomus) and Microtox® bioassays. Sediment and soil samples also were analyzed for semivolatile organic compounds, including polycyclic aromatic hydrocarbons (PAHs) and pentachlorophenol.

At four of the five sediment sampling locations, bioassay Cleanup Screening Level endpoints were exceeded. At both soil sampling locations, carcinogenic PAHs exceeded Method B Soil Cleanup Levels.

During September 2003, sediments and soils were collected from upper and lower segments of Little Squalicum Creek, a small stream in Bellingham, Washington. The samples were evaluated in accordance with applicable regulations for determining whether chemical contamination presents a threat to human health and the environment. All samples were analyzed for contamination, and sediment samples also were tested with a suite of bioassays to evaluate their toxicity to aquatic life. The study was conducted to assist the City of Bellingham in planning a comprehensive investigation of pollution in Little Squalicum Creek and the creek area prior to developing the site into a community park and trail corridor.

Both sediment and soil samples were analyzed for semivolatile organic compounds, including polycyclic aromatic hydrocarbons (PAHs) and pentachlorophenol. A nearby wood treatment facility reportedly has had spills into the creek of a wood preservative solution that contains these chemicals. Toxicity testing of the sediment samples was conducted using amphipod (10-day Hyalella), midge (20-day Chironomus), and Microtox® bioassays.

For sediment, both lines of evidence (chemical analysis and biological testing) provide substantiation for contamination at levels of concern in the two stream segments investigated. Almost every sediment sample was toxic in one or more bioassay tests and had chemical concentrations exceeding risk-based numerical values. There was also a general concordance between chemistry and biology: the most heavily contaminated sample failed all bioassay tests, while the least contaminated sample failed none. All but one of the sediment stations tested exceeded recommended freshwater Sediment Quality Standards or Cleanup Screening Level bioassay endpoints.

Chemical analysis of soil also provided substantiation for contamination at levels of concern in the two stream segments investigated. At both soil sampling locations, carcinogenic PAHs exceeded Model Toxics Control Act Cleanup Regulation (Chapter 173-340 WAC) Method B Soil Cleanup Levels.

Link to EIM data for User Study ID LSP2