In Yigo, the northernmost village in Guam, there is a well that cannot be shut down.
Known as Y-15, the well sits atop the island’s northern aquifer, which supplies around 80% of the island’s drinking water. Even if contaminants are detected, Y-15 has to keep pumping. There is simply no alternative.
The well also sits just below a hill near Upi Elementary School—attended by around 400 children—and just outside the back gates of Andersen Air Force Base, which hangs over the community like a permanent shadow. Generations of Indigenous CHamoru families have called Yigo home, relying on these waters for drinking, cooking, and other daily activities.
But in September 2025, one such family learned that the well supplying their home of 17 years was contaminated with high levels of dieldrin, a pesticide once widely used on crops and for termite control beginning in the 1950s. The Environmental Protection Agency (EPA), which classifies dieldrin as a probable human carcinogen, banned all uses of the pesticide in 1987 over concerns about its damage to the environment and links to serious health effects, including cancer, Parkinson’s disease, and reproductive issues such as decreased fertility and increased numbers of stillbirths. Because dieldrin accumulates in the body, long-term exposure—even in small amounts—can cause serious harm, according to the EPA.
More than 1,200 residents of Yigo were told not to drink water from Y-15 because of dieldrin contamination.
The news hit Leevin Camacho, the homeowner who learned of the contamination, with a mix of anger and fear. He thought immediately of his two young sons. Although members of his family don’t drink straight from the tap, the water touches nearly everything they do: cooking meals, brushing their teeth, showering at the end of long, humid days.
“While we were there feeding our kids, doing a lot of stuff, there was pesticide in the water,” he told Prism in November.
Camacho knew his family could adjust to the “do not drink” order issued by Yigo officials. As a lawyer and former attorney general of Guam who grew up in a military household, he had the resources to install a costly home filtration system or buy bottled water each week. But he worried about everyone else in Yigo—especially fellow CHamorus who, unlike him, didn’t have as many options.
Dieldrin is just one piece of a much larger and troubling environmental legacy in Guam.
Per- and polyfluoroalkyl substances (PFAS)—better known as “forever chemicals”—have also been detected across the island’s water systems. These compounds can persist in soil and groundwater for decades, and they have been linked to a range of health effects, including cancer, immune and thyroid dysfunction, liver and kidney disease, and serious reproductive issues.
For Monaeka Flores, an advocate with the grassroots environmental organization Prutehi Guåhan, the island’s environmental problems are inseparable from the military buildup that has reshaped the island. From hazardous waste dumping, base construction, and open-air detonations of munitions to live-fire exercises in sensitive habitats, advocates say that Guam’s land and water bear the toxic legacy of the U.S. military.
“Questions that we couldn’t answer”
In September 2025, local officials gathered Yigo residents at a village gymnasium to share the alarming details of their water’s contamination: Dieldrin at the Yigo well measured 1.76 micrograms per liter—more than eight times the threshold that Guam EPA considers within the acceptable cancer-risk range. Two other wells on the island also showed elevated levels of the pesticide, though not as high as the one in Yigo. Unlike Y-15, these two wells were shut down.
Once the information was made public, Yigo Mayor Frances Lizama said her phone rang nonstop.
“A lot of the calls were about health, about when we are going to get our safe drinking water—questions that we couldn’t answer,” Lizama said during an interview at her office late last year.
The discovery also raised questions about the timing of when residents were told dieldrin was in their drinking water.
Dieldrin has been detected in Guam’s groundwater for years. In 2012, the EPA notified Guam authorities of its presence in several wells. But because dieldrin is not federally regulated in drinking water, there was no standard requiring utilities to take action or issue a public warning. Guam EPA and Guam Waterworks Authority (GWA), the public utility that manages Guam’s water and wastewater systems, said the issue was discussed in public meetings before September 2025.
It wasn’t until 2024 that Guam EPA approved “Interim Action Levels” for dieldrin—essentially a trigger for warning the public. The standard, which only took effect on Aug. 1, 2025, required the public to be notified of any exceedance within 30 days. If pesticide levels surpass the short-term health advisory level of 0.5 parts per billion, customers are required to be notified within a day. GWA was notified on July 30 that samples showed levels well above the threshold.
However, it took the agency more than a month to issue an advisory. Capt. Elizabeth DeGrange, a senior science adviser with Guam EPA, attributed the gap to the Interim Action Level’s unclear wording regarding next steps.
Guam officials got to work treating the Y-15 well water using granular activated carbon filtration, which traps the chemicals as water passes through tanks filled with highly porous carbon granules. In November, the Guam EPA lifted the “do not drink” advisory when dieldrin was no longer detected in the water. But for many residents, the crisis is far from over. During a Senate hearing in December, the Guam EPA said that 33 of the island’s 120 wells still have detectable levels of dieldrin, but they are currently below regulatory limits.
Camacho’s law firm helped file around 800 claims against GWA and Guam EPA, seeking a total of $167.5 million in damages over dieldrin contamination of the Y-15 well. Most of the claims remain under review. The agencies have six months to respond, Camacho said. If the government rejects the claims or fails to respond within the statutory period, a lawsuit may be filed.
Today, the source of the contamination remains officially unconfirmed. Guam EPA has not identified a definitive origin and warned that tracing one may be nearly impossible, but the agency told senators in January that Andersen Air Force Base is a potential source of the contamination.
The Joint Region Marianas (JRM), which oversees Andersen Air Force Base, is “committed to a thorough, science-based investigation into the source of dieldrin contamination,” spokesperson Kristina Wiedemann told Prism in an email. “JRM will continue working closely with federal and local regulatory agencies throughout the process and will use the results to inform any appropriate future actions.”
The U.S. military’s existing footprint in Guam and its continued expansion remains an ongoing threat to the island’s environment, advocates told Prism.
The long arc of colonization
While Guam is only 30 miles long and nine miles wide, the U.S. Defense Department controls roughly a quarter of its land—and military expansion is accelerating. Much of the military buildup on the island is justified on the grounds of national security as the U.S. seeks to strengthen its position in the Pacific amid tensions with China and North Korea.
A missile defense system designed to protect the territory from potential outside threats, live-firing range complex, and new Marine Corps base are currently in the works. The buildup could also expose more people to potential environmental contamination. Roughly 10,000 active-duty personnel, their dependents, and government civilians are expected to arrive by 2036.
Before Guam became a “strategic outpost” for the U.S., it was a constellation of small villages where the Indigenous people of the Marianas cultivated taro, breadfruit, and avocados, fished the surrounding seas and inland streams, and lived in homes built on latte stone pillars. Then, a long arc of colonization occurred: first under Spain in 1668, then the U.S. in 1898, followed by a violent Japanese occupation in World War II, until American troops fought their way back. After the war, the U.S. military buried large volumes of munitions and other waste in places such as Mongmong-Toto-Maite, often without informing the people who lived there.
One of those families was the Leon Guerreros. Victoria Leon Guerrero grew up in Toto, unaware that the soil she played in with her cousins and harvested avocados from was laced with hazardous military debris. In 2008, after her brother unearthed an unexploded bomb in their yard, the Army Corps of Engineers tested their land. The results revealed contamination from lead, arsenic, and polychlorinated biphenyls (PCBs)—chemicals linked to a range of health risks, including birth defects, developmental delays, and cancers.
The pollution was personal.
Guerrero’s first child was born with a rare abdominal wall defect and lived only eight hours. She has long wondered whether growing up on heavily contaminated land played a role. Several of her relatives have also been diagnosed with cancers.
Our lives are regularly put at risk in very serious ways. We only learn about it after the fact, when it becomes a crisis. And even in those instances, there’s no apology, no accountability.Victoria Leon Guerrero, activist and Guam resident
“Our lives are regularly put at risk in very serious ways,” said Guerrero, who is leading decolonization efforts on the island. “We only learn about it after the fact, when it becomes a crisis. And even in those instances, there’s no apology, no accountability. There’s just speculation that it’s somehow connected to the military presence.”
What is unfolding in Guam is not happening in isolation.
From Okinawa, Japan to the Marshall Islands and the Diego Garcia military base in the Chagos Archipelago, communities living near U.S. military bases have documented patterns of environmental harm, including contamination linked to toxic chemicals and hazardous waste.
There is “very significant environmental damage” due to leaks and the military’s accidental—or sometimes intentional—dumping of hazardous, toxic materials, said David Vine, a political anthropologist and author of “Base Nation: How U.S. Military Bases Abroad Harm America and the World.” “It’s a clear pattern across the network of bases in the Pacific and around the world, including the 50 states,” he told Prism
Guam’s many environmental problems are concentrated around military bases, the island’s airport, and sites where firefighting occurred. As just one example: A major source of PFAS contamination on the island is the powerful fire suppressant known as Aqueous Film Forming Foam, which is used to extinguish jet fuel fires.
Perfluorooctanesulfonic acid (PFOS), a forever chemical in the PFAS class, was also detected in Guam’s public water systems. GWA estimates that 34 production wells may require PFAS treatment under the EPA’s new standards, which sets a limit of 4 parts per trillion for two of the most common PFAS compounds.
Advocates also point to yet another environmental problem on the island: the military’s open-air burning and detonation of excess or obsolete munitions on Tarague Beach, a stretch of northern Guam between the Pacific Ocean and dense jungle that is the ancestral land of CHamoru people. Like the well where high dieldrin levels were detected, the site sits directly above the island’s primary freshwater source.
While no open burning has occurred there since 2002, the Air Force has continued detonating hazardous waste explosives at the site. This open burning and detonation of munitions releases toxic contaminants, including lead, arsenic, and PFAS into the air, soil, and groundwater, according to advocates. Runoff can also reach the ocean, threatening the families who gather on nearby beaches and fish at culturally significant coastal sites.
Last year, Prutehi Guåhan, represented by Earthjustice, sued the Air Force and the Department of Defense over these harmful practices. The group argues the agencies failed to evaluate the cultural and environmental impacts of open-air disposal or consider safer alternatives. The Supreme Court agreed to hear the case this October. The case comes as the high court has narrowed the scope of federal environmental review. Notably, last year SCOTUS limited the environmental impacts agencies are required to consider under the National Environmental Policy Act.
Restoring sovereignty
The environmental harms to Guam’s waters and landscapes are inseparable from the military presence and the island’s political status as a U.S. territory. As such, Guam has little agency over the placement and operation of military installations.
This includes what’s known to the CHamoru people as Litekyan, one of the island’s most culturally and environmentally significant places. More broadly known as Ritidian, it is located 30 minutes from Guam’s capital. Its pristine white sand beaches, ancient limestone forests, and endangered species, including the Mariana fruit bat and the eight-spot butterfly, set it apart from the rest of the island.
But on the trail leading to the shoreline, the forest is eerily silent—no birdsong, only the sound of waves breaking in the distance. That silence reflects the toll invasive brown tree snakes have taken on Guam’s native bird population. The snakes were accidentally introduced to Guam in the 1940s via U.S. military transport after World War II.
To reach the beach, visitors must now pass through the wildlife refuge gate and drive past warning signs about nearby Marine training activities. For Maria Hernandez, Litekyan is more than a protected landscape; it is her family’s ancestral home. The road leading to the beach was once paved by her great-grandfather.
“His lemmai trees are still there,” she said. “They’re bearing fruit, so it’s a symbol of resistance.”
But in the early 1960s, the U.S. Navy seized her family’s land. In 1993, the property was handed over to the U.S. Fish and Wildlife Service to create a wildlife refuge. Today, the area is facing new threats: The U.S. military has built a missile firing range in the middle of the ancient forest and plans to designate parts of Litekyan as a “Surface Danger Zone” for a live-fire training range complex.
The military’s proposed expansion would only further restrict CHamoru families’ remaining access to land and waters. “These are some of the most pristine waters,” Hernandez said, noting that the military could block fishers from accessing the water for more 263 days each year.
The JRM told Prism in an emailed statement that it takes residents’ concerns about the environmental impacts of military activities seriously, and that the agency is “committed to responsible environmental stewardship and working with federal and local regulatory agencies to protect human health and the environment.”
Activists, community leaders, and CHamoru families increasingly frame their struggle against the military’s pollution and contamination not only as an effort to protect fragile ecosystems, but also as a broader fight for demilitarization and decolonization. They are demanding both the removal of militarized infrastructure and the restoration of sovereignty over their ancestral lands.
“The only true way to protect the environment is to truly have sovereignty, to have voice and power, to not be unincorporated or a territory of another place, but to be able to really own and protect our lands and waters with full voice,” said Victoria Leon-Guerrero, whose home had been found to be surrounded by contaminated soil. “As long as we don’t have that, this environmental degradation will continue.”
The main options for Guam’s political status are statehood, free association, or independence.
For Gov. Lou Leon Guerrero, a distant relative of Victoria Leon-Guerrero, Guam must carefully weigh whether it can manage itself independently. “We have to say to ourselves: Are we ready? Do we have the capability? Do we have the capacity? Do we have the competency to do that on our own without our federal support?” she said. “We have to think about that.”
Victoria Leon Guerrero, however, believes that attempting independence is worth pursuing, even if the transition is difficult. Other nations, such as the Philippines, have faced similar challenges. Beyond the political definition, independence for Leon Guerrero means choice.
“It allows us the ability to truly protect who we are,” she said, “to truly protect the inherent relationship between the CHamoru people and these lands and waters.”
Editorial Team:
Tina Vasquez, Lead Editor
Lara Witt, Top Editor
Rashmee Kumar, Copy Editor
Gaea Cabico is an award-winning journalist from the Philippines who reports on climate change, environmental issues, and energy through a social justice lens.
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