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

On February 25, 2026, the Guam Waterworks Authority (GWA) provided a followup to the the Authority's January 29 update on GWA's dieldrin mitigation efforts following the conclusion of a joint oversight hearing held by the 38th Guam Legislature.

Point-of-Entry (POE) Program:

• As of February 25, 2026, GWA has received 339 applications for POE provision and installation.

•  GWA has completed 162 home assessments with American Watertek since January 28, 2026. As today, an additional 20 home assessments have been scheduled.

•  GWA’s second awarded contractor – SBS Guam dba Water Doctor is scheduled to begin home assessments on March 3, 2026.

•  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. Estimated time of arrival is forthcoming.

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 accepted from now and until within 30 days of date of GWA 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:

• NEPA requirements have been met as the Guam State Historic Preservation Office and U.S. Fish and Wildlife issued concurrence to GWA.

• On February 12, 2026, GWA contractors successfully uninstalled decommissioned GAC vessels at Well A-8 and began the refurbishment process for vessel installation at Well M-4.

• Well Y-15’s interim treatment system will remain online until the permanent GAC treatment system is installed and is tested to yield non-detect levels of dieldrin for four (4) consecutive weeks.

• Once Y-15’s permanent GAC treatment system has demonstrated four (4) consecutive weeks of non-detect levels of dieldrin, the interim treatment GAC vessels originally commissioned on October 12, 2025 will be refurbished and relocated for commissioning at Well D-17.

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

Dieldrin Testing Data from Samples Collected February 12, 2026:

• In our January 29 update earlier this year, 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 29, 2026 reporting with analytical data from samples collected on February 12, 2026:

Dieldrin Sampling Results - Running Annual Average (RAA) – 124 SAMPLE LOCATIONS
Wells	RAA	Remarks
30	Non-Detect (ND)	• No detections for dieldrin
86	0.01 ppb to 0.09 ppb	• 86 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; RAAs for both are 0.014 and neither has had RAA over the IAL.
4	0.15 ppb to 0.19 ppb	• M-4 offline since 10/3/25; RAA is 0.18 ppb; treatment under construction • M-3 is being placed on-line intermittently if needed operationally to meet customer demand; Result for samples taken on 2/12/26 is 0.15 ppb; RAA is 0.17 ppb. • EX-11 remains online and has not had a RAA over the IAL; Result for samples taken on 2/12/26 is 0.16 ppb; RAA remains at 0.16 ppb. • D-17 offline since 7/31/25; treatment under construction. Result for samples taken on 2/12/26 is 0.09 ppb. RAA remains at 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 March 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.

GEPA has organized a townhall meeting with Yigo Mayor Frances Lizama at 6:30 p.m. on February 25, 2026 at the Yigo gym. GWA will participate in the meeting to provide updates on the Authority’s dieldrin mitigation efforts.