Anacortes Former Water Treatment Plant

Last Updated:  May 2025   

Cleanup completed
Cleanup construction is complete. The cleanup actions selected in the 2021 Cleanup Action Plan have been completed. These included:

• Excavation and off-site disposal of polychlorinated biphenyls (PCB)-contaminated soil above 1 mg/kg (MTCA Method A standard).
• Demolition of the former water treatment structures, including the Sedimentation and Filtration basins, and removal of PCB-contaminated building materials.
• Removal of regulated materials (e.g., asbestos, lead paint, residual chemicals).
• Confirmation sampling to make sure cleanup levels were met.
• Site restoration, including backfilling, grading, hydroseeding, and gravel surfacing.

Cleanup construction began in July 2023 and concluded in April 2024. Waste disposal and confirmation sampling met applicable state and federal regulations. Remaining backfill with lagoon soil will be completed under a separate city project. For full explanations and details, see the Construction Completion Report and its Appendices.

The Site is located next to the Skagit River in Mount Vernon (see map) and is next to the current water treatment plant, which provides the drinking water for the City of Anacortes (City) and surrounding communities. 

Drinking water information

For more information on the City’s drinking water monitoring, see below and visit www.safeandcleanwater.com. 

The Model Toxics Control Act (MTCA) is Washington’s environmental cleanup law. It provides requirements for contaminated site cleanup and sets standards that protect human health and the environment. Ecology enacts the MTCA and oversees cleanups. The MTCA site cleanup process is completed in steps (see graphic below) over a variable timeline. 

• 2021-2022: Complete design of the cleanup and implement the cleanup action.
• Summer 2023: Cleanup construction begins.
• 2023-2024: Cleanup construction ongoing, ending in April 2024.
• Winter 2025: Construction Completion Report submitted to Ecology.

The Cleanup Action Plan (CAP) for the Anacortes Former Water Treatment Plant was finalized by Ecology in December 2021. The CAP addressed contamination from PCBs found in building materials and shallow soil at the site.

The selected cleanup approach included:

• Excavation and off-site disposal of PCB-contaminated soil above 1 mg/kg, the MTCA Method A standard for unrestricted land use.
• Demolition of former water treatment plant structures, including the Sedimentation Basin, Filtration Basin, and Administration Building.
• Removal of asbestos and regulated materials, including lead-based paint and residual chemicals.
• Confirmation sampling of soil and concrete surfaces to verify that PCB levels met cleanup standards.
• Site restoration, including backfilling, regrading, hydroseeding, and gravel surfacing.

These actions were designed to permanently remove the sources of contamination and prepare the site for safe future use.

See the below documents for more information:

Response to Comments Summary (July 2021)

Final Consent Decree (December 2021)

PCBs were found in the exterior wall coatings of the Sedimentation and Filtration basins and adjacent soils (see “Soil Removal” in figure ). The thin veneer coating on the exterior of the concrete basin walls of the Sedimentation and Filtration Basins is the source of localized PCB contamination in shallow soils. PCBs in the coatings were also absorbed into the top 1- to 3- centimeters (cm) of the concrete walls, which are just over 20 cm thick. The figure to the left shows the typical PCB concentrations in the coating and adjacent concrete of Site structures. 

No contamination was found in the Sedimentation and Filtration basin interior walls.

In 2015, while conducting a demolition and hazardous materials assessment of the decommissioned Site, samples of building materials and soil were found to contain polychlorinated biphenyls (PCBs). The Remedial Investigation and the 2015 Hazardous Materials Assessment found:

• Groundwater and surface water:  The field sampling confirmed that there was no indication of PCBs released to groundwater or surface water. 
• Building Materials:  PCBs were found in the exterior coatings of the Sedimentation and Filtration Basins and some of the building materials of the Administration Building. This is the source of PCBs in soil at the property.
• Soil:  PCBs were only found in shallow soils between 0 to 12 inches below ground surface on a limited portion immediately next to Site structures. PCBs were detected in shallow soils at concentrations that exceed the residential/unrestricted land use cleanup level (1 milligram per kilogram [mg/kg]) under MTCA. These shallow soils will be removed and disposed off-Site in a permitted landfill. See figures on page 3 of the Fact Sheet.  

For more information on cleanup standards download the fact sheet: “Focus on: Washington’s Environmental Cleanup Law”

BACKGROUND AND LOCATION
The Site is located at 14489 River Bend Road in Mount Vernon. The former plant was constructed on the property between 1969 and 1970 to treat water from the Skagit River prior to transfer to the City of Anacortes municipal water storage and distribution network. The former plant's structures were decommissioned in 2013 when the new water treatment plant (built on a different part of the same property) became active.

Based on the Remedial Investigation, the Site consists of these decommissioned structures and the adjacent contaminated soils (click on site layout to the left for larger image):

• Filtration Basin: a nearly 8,000 square foot concrete basin that used anthracite, sand, and gravel for water purification. 
• Sedimentation Basin: an over 19,000 square foot concrete basin that featured gravity flow through the system into clean water overflow troughs for settled particulate collection.

The City conducted regular sampling of drinking water produced from the former Plant beginning in 1976 and continuing throughout operation. No samples of drinking water tested for PCBs ever contained detectable concentrations of PCBs.

In 2017, the City conducted an evaluation of potential human health risks associated with contamination at the Site and determined that no adverse health effects are likely to have occurred to customers, workers, or water plant visitors as a result of PCBs at the former Plant. 

For more information, to sign-up for updates, and to view the  Human Health Assessment go to:  www.safeandcleanwater.com

Contact the City of Anacortes:   info@safeandcleanwater.com 360-299-1950