GWA Provides Mitigation Update to Sen. Lujan – Jan. 29, 2026

On January 29, 2026, the Guam Waterworks Authority (GWA) provided the first update on the Authority's dieldrin mitigation efforts following the conclusion of a joint oversight hearing held by the 38th Guam Legislature.

In the update to Sen. Jesse A. Lujan, Vice Speaker Tony Ada and Committee on Health Chair Sen. Sabrina Salas Matanane, GWA stated that the Authority "remains firmly committed to our dieldrin mitigation plans, and we appreciate the support from you and your office and all of our stakeholders as we progress in our restorative efforts to provide safe water to the Santa Rosa, Yigo community impacted by the dieldrin interim action level (IAL)."

Point-of-Entry (POE) Program:

• GWA issued notices to proceed to two (2) contractors this month: American Watertek and SBS Guam.

• On January 28, 2026, Yigo Mayor Frances S. Lizama was provided an operational briefing by GWA’s POE GWA contractor along with personnel from GWA’s customer care, operations and engineering units at the Yigo Mayor’s Office.

• Home assessments commenced on January 28, 2026 following the operational briefing with Mayor Lizama.

• Home assessments involve evaluating plumbing schematics, space provisions, locating water mainlines and identifying private piping material to ensure quick and proper installation of the POE treatment systems.

• GWA customer care representatives continue contacting POE applicants to schedule home assessments.

• POE treatment systems are en route to Guam, and assessed customers will be contacted to schedule final installations once systems arrive.

• As of January 22, 2026, GWA has received 316 applications for POE provision and installation.

As previously stated during the opening joint oversight hearing held on October 24, 2025, GWA’s POE program was first initiated and publicly announced on October 10, 2025. Following the announcements, GWA sent direct mailers with applications and program details via postal mail to affected Santa Rosa/Yigo customers on November 5, 2025.

Although an interim granular activated carbon (GAC) treatment system was commissioned for well Y-15 in Yigo on October 12, 2025 and has been producing water without any detections of dieldrin since then, GWA POE applications will continue to be received from now and until within 30 days of the commissioning of the permanent GAC treatment system at well Y-15 in Yigo. The commissioning date for all three GAC treatment systems is forthcoming.

GAC Treatment System Construction:

• Construction competition is still targeted by or before this summer.

• GAC construction work continues at the M-4 well site. GAC vessels decommissioned from well site A-8 will be refurbished and installed at M-4.

• GAC construction at D-17 will follow the completion of the permanent system at Y-15.

Dieldrin Testing Data from Samples Collected January 14, 2026:

• At the conclusion of the joint oversight hearing held on January 7, 2026, GWA had previously reported the status of entry points that tested higher than, or equal to 50% of the IAL for dieldrin.

• The table below provides a status update to the January 7, 2026 reporting with analytical data from samples collected on January 14, 2026:

Dieldrin Sampling Results - Running Annual Average (RAA) – 124 SAMPLE LOCATIONS
Wells	RAA	Remarks
33	Non-Detect (ND)	• No detections for dieldrin • “Do Not Drink Without Treatment” advisory for Y-15 was rescinded on 11/13/25.
83	0.01 ppb to 0.09 ppb	• 83 locations are less than 0.1 ppb or 50% of the IAL
4	0.10 ppb to 0.14 ppb	• A-23 & A-25 offline for PFAS since 2016; treatment under construction • M-2 & D-18 remain online; neither has had RAA over the IAL.
4	0.15 ppb to 0.19 ppb	• M-4 offline since 10/3/25; RAA is 0.17 ppb; treatment under construction • M-3 is being placed on-line intermittently if needed operationally to meet customer demand; RAA is 0.18 ppb. • EX-11 remains online and has not had a RAA over the IAL; RAA is 0.16 ppb. • D-17 offline since 7/31/25; treatment under construction. Result for samples taken on 1/14/26 is 0.09 ppb. RAA is 0.09 ppb.

The Guam Environmental Protection Agency’s (GEPA) current IAL requires that all entry points (wells) in a public water system must be tested for dieldrin on a quarterly basis. However, in an ongoing effort to exercise due diligence, GWA has made the decision to increase the frequency of monitoring certain wells which show results at the “half-IAL,” or 50% of the IAL, as part of our mitigation efforts. The next monthly sampling for dieldrin is scheduled for February 12, 2026.

GWA will continue to provide timely and pertinent updates to the community as they become available. As a reminder, information about dieldrin mitigation may also be found on GWA’s microsite: guamwatersafety.com.