Publication Summary

Sediment in Ostrich Bay, near Bremerton, Washington, was tested for toxicity using four bioassay tests in accordance with the Washington State Sediment Management Standards. The sediment samples were also chemically analyzed. A former Naval ammunition depot discharged metals and other chemicals into the bay during operations from 1904 to 1959.

Biological regulatory criteria for sediment quality were exceeded at six of the 12 sampling stations, based on the bioassay testing. The Sediment Quality Standard for mercury was also exceeded at six stations.

The basis for the observed sediment toxicity is unknown. Elevated sulfide levels in Ostrich Bay do not appear to be a contributor. A previous attempt to identify a metal or organic contaminant responsible for the toxicity of Ostrich Bay sediments also was unsuccessful.

Sediments from 12 sampling stations in Ostrich Bay, near the city of Bremerton, Washington, were evaluated for compliance with the Washington State Sediment Management Standards. A former Naval ammunition depot discharged metals, munitions chemicals, and other organic chemicals into the bay during operations from 1904 to 1959.

Samples were collected in October 2004, and evaluated for toxicity and chemistry. Four bioassay tests - amphipod, juvenile polychaete, larval bivalve, and Microtox - were conducted on each sample. Chemical analyses included semivolatile organics, metals, explosive compounds (nitroaromatics, nitramines, and perchlorate), and sulfides.

Both biological and chemical concentration-based regulatory criteria were exceeded. Six of the 12 stations did not meet the Sediment Quality Standards (SQS) based on bioassay testing. In addition, the mercury concentration SQS was exceeded at six stations, primarily in the same area where mercury exceedances were found in a 1994 investigation. The chemical concentration SQS for other metals and organic compounds were met, with the exception of benzoic acid at four stations.

The basis for the observed sediment toxicity is unknown. Elevated sulfide levels in Ostrich Bay do not appear to be a contributor. A previous attempt to identify a metal or organic contaminant responsible for the toxicity of Ostrich Bay sediments also was unsuccessful.

Link to EIM data for User Study ID NBLA0002