Dieldrin IAL Update Release No. 2: INTERIM TREATMENT SOLUTION FOR WELL Y-15 COMPLETE AND ONLINE

(Mangilao, GU) — On Oct. 12, the Guam Waterworks Authority (GWA) completed the successful installation of its interim treatment system at well Y-15 in Yigo. The installation is a necessary first step which GWA must take for the Guam Environmental Protection Agency (EPA) to lift the “Do Not Drink without Treatment” advisory.

“With the installation of this treatment system, our community can be assured that the water supply meets all federal and local drinking water standards while we continue working toward our long-term solution for Y-15,” said GWA General Manager Miguel C. Bordallo, P.E.

The interim treatment system at well Y-15 uses granular activated carbon (GAC) filtration, an EPA-approved and proven technology used to remove contaminants like dieldrin and PFAS from drinking water. With the GAC filtration treatment system in operation, GWA will conduct weekly sampling at Y-15 at the request of Guam EPA to ensure the system’s efficacy to comply with the Interim Action Level for dieldrin. Analysis will be expedited and performed by an EPA-certified laboratory in the U.S.

After four consecutive weeks of satisfactory laboratory results, GWA will confer with Guam EPA to lift the advisory that was issued to affected GWA customers in the Santa Rosa/Yigo area:

In 2023, GWA began work on a full-scale treatment solution to address dieldrin and other potential contaminants across its system. This multi-year project remains on schedule and is estimated to be completed by summer 2026. The investment made in 

the full-scale treatment facilities will provide a long-term safeguard to ensure drinking water remains safe and reliable for the community.

In the meantime, GWA will continue to operate the interim GAC treatment system at well Y-15, and will perform monthly sampling and analysis for dieldrin. Results will be shared with the public and will be available for review by visiting guamwatersafety.com. Additionally, GWA will provide timely updates on progress toward the 2026 permanent treatment system.

As part of GWA’s coordinated efforts with Guam EPA and the Office of the Governor, several other actions have been implemented to assist affected customers, including:

• Bottled Water Distribution: On Oct. 2, GWA began bottled water distribution and select home deliveries for affected customers in the Santa Rosa/Yigo area with assistance from the Office of the Governor and Yigo Mayor’s Office. Water distribution is located at the Yigo Gym, Monday-Friday from 9 a.m. to 1 p.m. and 4 to 7 p.m., and Saturday-Sunday from 9 a.m. to 1 p.m.

• Point-of-Use (POU) / Point-of-Entry (POE) Systems: On Oct. 10, GWA initiated and announced procedures for reimbursements for customer-purchased POU/POE treatment systems, as well as application procedures for GWA-provided POE systems for affected customers in the Santa Rosa/Yigo area. Details are available at guamwatersafety.com.

• Agricultural Inspections and Monitoring: Guam EPA has continued to partner with Guam Department of Agriculture and initiated inspections of farms, as well as the design of a sampling and testing strategy to help us better assist dieldrin contamination and related risks.

• Updated Guam EPA dieldrin website: Guam EPA has added a direct link to dieldrin-related information to their website’s homepage, available in the upper right hand corner, and also at epa.guam.gov/dieldrin-information. 

In response to the water advisory, GWA recently launched guamwatersafety.com, a microsite that will serve as a trusted source of water safety information, keeping the public engaged and informed.  Residents can also use the site to stay up-to-date on GWA’s latest action to fight legacy contaminants in Guam’s groundwater. 

Helpful contact information:

Guam EPA Community Hotline	(671) 888-4342	7 a.m. to 9 p.m. daily, for questions regarding health risks and water quality.
Guam Waterworks Authority	(671) 647-7800 or (671) 647-7803	7 a.m. to 9 p.m. daily, for questions regarding whether you are impacted.