Publication Summary

The Washington State Department of Ecology conducted a screening level survey of sediment quality in four harbors in the San Juan Islands during May 1997. The primary objective of this investigation was to assess the occurrence and extent of toxic chemicals associated with marina activities in the four harbors. A secondary objective was to determine if chemical concentrations exceed marine Sediment Quality Standards under the Sediment Management Standards or the Puget Sound Dredge Disposal Analysis interim screening level for tributyltin.

The Washington State Department of Ecology (Ecology) conducted a screening level survey of sediment quality in four harbors in the San Juan Islands during May 1997. The primary objective of this investigation was to assess the occurrence and extent of toxic chemicals associated with marina activities in the four harbors. A secondary objective was to determine if chemical concentrations exceed marine Sediment Quality Standards (SQS) under the Sediment Management Standards or the Puget Sound Dredge Disposal Analysis (PSDDA) interim screening level for tributyltin.

Sampling was conducted in Friday Harbor and Roche Harbor (San Juan Island), West Sound (Orcas Island), and Fisherman Bay (Lopez Island). Sediments were collected from four to eight locations within each harbor to represent boat slips, boat moorage areas, and areas slightly beyond the moorage perimeter to assess drift of the target chemicals. Sediments potentially influenced by boatyard activities were also sampled, except in Roche Harbor which does not have a boatyard. Two locations from Mud Bay were sampled to establish background levels for the target chemicals. All samples were analyzed for the following parameters: total organic carbon, chromium, copper, lead, zinc, semivolatile organics, and butyltins.

Overall metals concentrations were low. More than half the results were below mean values obtained at the Mud Bay (Lopez Island) reference site. Mean concentration of metals at all harbors were an order of magnitude below the SQS. The highest metals concentrations (lead, copper, and zinc) were found in West Sound.

Total LPAH and HPAH (low and high molecular weight PAHs) concentrations were elevated above reference sediment values at all four harbors, although none exceeded the SQS. Similarly, individual PAHs were elevated at all four harbors but also below SQS. One exceedance of SQS occurred for fluoranthene, in West Sound.

Friday Harbor sediments were the most contaminated with the target semivolatiles; 76% of the highest concentrations were found in this harbor. None of the concentrations exceeded SQS, however.

TBT concentrations were generally elevated above reference levels in all four harbors. Elevated TBT concentrations were most evident in West Sound sediments, and the two highest values were from this harbor. Concentrations were up to 67 times the PSDDA interim screening level. It is recommended that biological testing of sediments from these locations be considered, to determine the potential for adverse biological effects.

Link to EIM data for User Study ID SJHARBS