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“ Across our island, our people— parents, grandparents, workers and business owners— are all asking the same fundamental question: Is our water safe to drink?” Sen. Jesse Lujan, chairman of the legislative committee on utilities, said at an oversight hearing on Dec. 11, 2025.“ That question alone should concern us all. It is not a question that any community should have to ask in 2025. It tells us that somewhere along the line, whether in testing, monitoring, communication or coordination, something has broken down. It is our duty as lawmakers to continue to dig deeper until we fully understand where, why and how we can fix it.”
While the dieldrin contamination at Guam Waterworks Authority’ s production wells in Dededo and Yigo drew wide attention, the presence of dieldrin and chlordane in Tumon Bay went unnoticed.“ Tumon Bay has been listed as impaired due to dieldrin and total chlordane levels for over two decades,” according to a January 2024 report prepared by PG Environmental LLC for the Guam Environmental Protection Agency.
“ Since that report, Guam EPA wrote and had approved a TMDL for dieldrin and chlordane in Tumon Bay,” said Michelle Lastimoza, GPA administrator.“ Dieldrin and chlordane exceeded water quality standards for fish tissue, so the existing concern in Tumon Bay is not swimming in the water or ingesting it but eating the fish caught in Tumon Bay,” Lastimoza said.
She said the results from the toxicological and laboratory analytical services will determine if a fish consumption advisory is needed to inform the public that there is a health risk associated with consuming fish caught in Tumon Bay.
GEPA has been evaluating increased sampling and analysis with the 2026 National Coastal Survey. Sediment samples were collected in 2025 and will be analyzed for dieldrin, chlordane and other pesticides. Fish samples collected during the survey will be analyzed for mercury, PCB and PFAS, not pesticides.
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Michelle Lastimoza
“ We are looking into dieldrin and chlordane analysis in wetland soils during the 2026 wetland surveys, but those results won’ t be available until mid to late 2027,” Lastimoza said.“ These samples will help identify the changes over time.”
Guam EPA is working with GovGuam partners to conduct potential source investigations. Its Environmental Monitoring and Analytical Services program is also drafting a proposal to monitor dieldrin and chlordane in Tumon Bay, East Hagatna Bay and the Tanguisson Beach area for human health assessment purposes. The proposal includes hiring toxicological services and laboratory analysis services.
Applicable human health advisories may be posted if future data from sampled fish tissue, sediment or possibly marine waters show exceedances of human health criteria for contaminants of concern, mercury, PCBs, PFAS, dieldrin and chlordane.
PFAS contamination tends to be more localized, generally detected in areas that were or are airfields and near industrial sites, DeGrange said.
PFAS chemicals are most often associated with aqueous film-forming foam, a firefighting product used for decades at military bases and airports to extinguish fuel fires. Much of Guam’ s contamination history is tied to land use during and after World War II, when the island became a major U. S. military hub. Pesticides were used aggressively to control insects and disease, and firefighting foams were used repeatedly at airfields and training sites.
There was also a concern about asbestos in former military areas such as the abandoned barracks in Tiyan. Guam EPA continues to evaluate these areas in coordination with federal partners.
Advances in testing technology now allow scientists to detect contaminants at much lower levels than before.“ Obviously, detection, testing and remediation technologies have progressed rapidly in the last couple of decades,” DeGrange said.
Despite those advances, Guam faces unique obstacles. Samples often must be shipped off-island for analysis, which adds time and cost. Tropical conditions can damage equipment and compromise samples. Funding remains a persistent concern.
“ In Guam, our primary challenges remain funding, the additional stressors of tropical conditions in their impacts to the testing equipment and samples, and the cost and logistics of having to ship samples off-island for testing,” DeGrange said.
With limited resources, agencies must decide which contaminated sites to address first. Risk to people and ecosystems is the primary factor.“ In general, we evaluate the risk to human health and ecosystems and prioritize sites that have the likelihood for the highest impacts to humans and those ecosystems,” she said.
Some sites fall under the U. S. Environmental Protection Agency’ s Superfund program and are listed on the National Priorities List. Those sites undergo a federally guided assessment and cleanup process, while others are managed locally with federal technical support.
Public concern about contamination is often tied to health outcomes, particularly Guam’ s high rates of certain cancers and neurological diseases. However, direct scientific links between local contaminants and specific illnesses remain difficult to establish.
“ There are very few studies available, very limited data regarding the actual impacts of many contaminants, dieldrin and PFAS among them, which link them to illnesses anywhere, let alone Guam,” De- Grange said.“ We have no data or direct studies linking health impacts to either of these chemicals.”
Guam EPA, the Guam Department of Public Health and Social Services and the Guam Department of Agriculture have requested a formal public health assessment from the Agency for Toxic Substances and Disease Registry.
Long-term exposure to certain chemicals can carry known risks.“ As with
Elizabeth DeGrange
many chemical contaminants, some people who drink water containing dieldrin in excess of recommended exposure limits over many years could experience problems with their liver or nervous system, and may have an increased risk of getting cancer,” she said.
Community awareness about contamination issues is uneven, according to DeGrange. Public involvement tends to increase when specific sites or regulatory actions are proposed.
“ For any rule-making action, all Gov- Guam agencies must put out for public comment and consideration what rules they are proposing and other supporting documentation for those rules,” she said.“ Oftentimes, when a specific issue is identified, we can see increased input from the public, and that also usually results in lots of opportunities for education.”
Moving toward cleaner soil and water on Guam will require sustained effort across multiple fronts, DeGrange said.“ Continued intentional and informed education and awareness will serve our community widely,” she said.“ We need to understand how our actions impact our whole community.”
She pointed to illegal dumping as an ongoing threat to groundwater and marine environments.“ Perhaps, if everyone understood the impacts and risk, they might make different choices about how or where they dispose of waste,” she said.
Scientifically, Guam EPA plans to continue expanding testing and partnerships.“ We’ re doing our best to leverage the latest technologies and research to support our actions, rulemaking and decisions,” DeGrange said.“ We also continue to partner with the island’ s institutions for higher education to leverage their expertise and resources, as well as to encourage interest in environmental sciences.”
( With additional reports from Mar-Vic Cagurangan)