Environmental Stewardship's Marine Program completes a countywide inventory of creosote pilings.

Creosote Inventory

Map showing the inventoried creosote pile locations (red dots) and sensitive nearshore habitats, including forage fish spawning habitat, eelgrass, and kelp.

In June 2024 Environmental Stewardship's Marine Program completed a countywide inventory of creosote pilings. The study provided the County with updated information on the extent and location of creosote remaining in the San Juan Islands. A total of 594 sites were surveyed across 26 islands in 2023 and 2024. A total of 8,076 pilings were assessed and 71.3% (5,850) of these were identified as wood pilings likely to have been treated with creosote, amounting to an estimated 7,344 tons of creosote in the County’s nearshore waters. The vast majority of surveyed sites were in private ownership of which 94.2% (n=414) were found to include creosote piles (n=5,309 piles).

In addition to identifying the locations and numbers of pilings the project also provided data on the extent to which creosote pilings overlapped with sensitive nearshore habitats, including eelgrass meadows and kelp, as well as proximity to forage fish spawning habitat. Creosote-treated wood pilings are a significant source of contamination to nearshore environments of the Salish Sea. As creosote leaches into the marine environment, it impacts forage fish spawning habitat, valuable eelgrass beds, and other nearshore habitats and species. Creosote vapors also pose a risk to human health. The removal of creosote from the nearshore environment is a priority of the Washington State Department of Natural Resources, as well as the County.

Conservation Credits or mitigation

While the vast majority of creosote pilings remaining in the islands' nearshore waters are private, a number of the County’s public marine facilities still include creosote piles. The County has been steadily working to upgrade their marine facilities and as they do the creosote piles are replaced with steel piles. Any work to maintain, replace, or on occasion develop new facilities must address their impacts to the marine environment and this is done in the form of mitigation. NOAA Fisheries have created a calculator tool that allows project proponents to objectively estimate how many conservation offsets (or mitigation) they will be required to provide based on the type of project they are undertaking. Conservation offsets or credits can take the form of removing for example, creosote pilings, solid float decking, or shoreline armoring. This calculator tool has been created based on the best available habitat science, it takes into account the key biological and physical factors such as proximity of forage fish spawning habitat, presence of eelgrass, and presence of feed bluffs. This project allowed the County to estimate how many conservation credits are available through the County’s marine facilities and other shoreline properties that can be applied to future efforts to upgrade these public marine facilities, a lifeline to those living in our island communities.

Conclusion

This project completed a comprehensive countywide inventory of pilings and structures in the nearshore waters of San Juan County to determine the extent of creosote remaining, where it is, and its proximity to environmentally, economically, and culturally important habitats. The assessment included a review of the permitting requirements to remove or replace creosote structures and an assessment of the conservation credits available at each of the County’s 12 marine facilities where creosote piles remain.

Project Factsheet: Mitigating contamination to nearshore habitat from creosote pilings.

Project Report and mapbook: Final San Juan County Creosote Inventory Assessment Report and mapbook June 2024