The Pesticide Papers - The Margin

This story was produced in collaboration with The Margin and The War Horse.

On a typically humid day on Guam in September 2025, Leevin Camacho received a phone call that made his stomach churn. 

Life on the tropical island—an unincorporated territory of the United States that plays a key role in the Pentagon’s military strategy against China—was slow paced, particularly in the semirural village of Yigo where much of Camacho’s extended family lived. But that morning, his phone rang with unusual news.

“I got a call from my mom,” said Camacho, 48. Some family members had received letters from the local water authority. “My mom was in a panic, telling me that my kids shouldn’t brush their teeth with the tap water because it contained a pesticide.”

In the letter, authorities said they had detected unsafe levels of a pesticide known as dieldrin in a well, connected to the fresh water aquifer below the village, which potentially represents “an unacceptable long-term cancer risk” to residents. It was the first time many people in the village had heard of dieldrin. The pesticide had been banned in the U.S. by the Environmental Protection Agency since 1987 because of concerns about its toxicity to humans and animals. 

When swallowed, dieldrin is readily absorbed by the gastrointestinal tract and can accumulate in fatty tissue. Long-term exposure has been associated with tumors, while large doses can cause convulsions, tremors, and cardiac arrest. 

Nine days after the letters went out to Yigo residents, the Guam Waterworks Authority and the Guam Environmental Protection Agency issued a joint statement saying they had been working since late 2023 to install a treatment system at the contaminated well supplying Yigo’s drinking water. 

For many residents, the revelation was stunning. How had officials known about the contamination for nearly two years without telling them? 

As the father of two young children, Camacho wondered what the contamination might mean for their health. Had he unknowingly exposed them simply by cooking dinner each night? 

The community wanted to know where the contamination had come from, but Guam’s environmental regulator said it didn’t know.

The affected well, known as Y-15, sits across the road from Upi Elementary, a school attended by many members of Camacho’s family. On the other side of the schoolyard fence is Andersen Air Force Base, one of the largest U.S. military installations in the Pacific.

Suspicion quickly fell on the base as a possible source of contamination. Andersen has a long history of using industrial chemicals hazardous to human health, and a federally funded cleanup of contaminated sites there has been underway since 1993.  

Last September, Rear Adm. Brett Mietus, commander of Joint Region Marianas, the military command for Guam and the Mariana Islands, sought to reassure residents, saying there was no indication that drinking water on military installations had been affected. Although well Y-15 does not supply the base, Mietus announced accelerated testing of military-managed wells “out of an abundance of caution.”

By early October, the military said its tap water was safe. Joint Region Marianas reported that it had sampled water in “all active military wells and surface water sources on military installations across Guam” and found no dieldrin above the action level of 0.2 micrograms per liter.

On the surface, the results appeared to distance the Air Force from the contamination. But internal discussions between Guam EPA and the U.S. Environmental Protection Agency raised questions about whether military officials had disclosed everything they knew.

The Supreme Court Fight Over the Future of Guam

In a months-long investigation, The Margin and The War Horse spoke with more than a dozen current and former Guam residents who believe the actions of the world’s most powerful military are poisoning them. Previously unreleased military records obtained by the news organizations provide new evidence about the extent of pesticide contamination on Andersen Air Force Base and what officials knew about it.

In the eight decades since fierce battles raged across Guam during World War II, military activity has left a legacy of contaminated land and groundwater. Residents, activists, and former Andersen personnel say they have lived with the consequences, including fears that exposure may have contributed to serious health problems.

The U.S. military is seldom identified as the source of contamination on Guam, and the local government rarely holds it accountable. Camacho, a former attorney general of Guam, described the military’s posture as, “We’re not responsible, you can’t prove it.” 

Our investigation uncovered military documents showing that the U.S. government has spent years excavating and relocating pesticide-contaminated soil as part of a housing redevelopment project at Andersen Air Force Base. The documents were obtained from Guam EPA under the Sunshine Reform Act, the territory’s public records law. 

Military reports and historical government records also show that the Air Force has acknowledged, on Guam and in other contexts, that pesticide contaminated soil could pose a health risk to personnel and nearby communities.

This article is the first in a two-part series examining how the U.S. military buildup on Guam—driven in part by preparations for a potential conflict with China over Taiwan—is affecting the island’s environment, public health, military personnel, indigenous CHamoru communities, and ultimately its sovereignty. (This story uses CHamoru, the officially adopted spelling in Guam.)

Newly obtained documents also show that the military is still contending with contamination from World War II and Cold War-era activities, even as it invests billions of dollars in expanding its presence on Guam. 

The Margin and The War Horse reviewed thousands of pages of previously unreleased records from the Guam EPA, including internal communications between military officials and environmental regulators. 

Among them were soil-sampling and management reports produced for the military’s multiyear housing-replacement project at Andersen Air Force Base, as well as communications detailing a forthcoming Joint Region Marianas-led investigation into the source of dieldrin contamination on base. 

Guam EPA also released hundreds of pages of records concerning the Air Force’s long-running disposal of World War II-era unexploded ordnance and munitions through open detonation at Tarague Beach in Yigo. The Air Force wants to continue the practice, which dates back to 1982, despite longstanding environmental concerns and the development of alternative disposal methods, such as controlled detonation chambers. 

Whether the Air Force was required under the National Environmental Policy Act to conduct an environmental review and consider alternatives is now before the U.S. Supreme Court in Department of the Air Force v. Prutehi Guåhan. Prutehi Guåhan is a community organization dedicated to protecting Guam’s culture and environment.

A ruling for the Air Force could narrow how the National Environmental Policy Act applies when federal activities are also regulated under the Resource Conservation and Recovery Act. The case has drawn briefs from 21 Republican-led states backing the Air Force and 11 Democratic-led states, along with the District of Columbia, supporting Prutehi Guåhan.

As both sides prepare for oral arguments before the Supreme Court on Oct. 7, The Margin and The War Horse obtained a Defense Department report from Guam EPA finalized in May evaluating alternatives to open detonation on Tarague Beach.

Guam EPA’s comments on the report show that the regulator disputes several of the Air Force’s conclusions and believes the service has interpreted its obligations under the Resource Conservation and Recovery Act too narrowly.  

Taken together, records related to the dieldrin contamination and open-detonation disputes show repeated friction between the Air Force and environmental regulators over how contamination is investigated, prevented, and addressed as the military pours billions of dollars into preparing Guam for a potential conflict. 

In one letter sent to Guam EPA offering technical advice on Air Force claims, the U.S. Environmental Protection Agency expressed concerns about Andersen Air Force Base’s response to requests that, according to the agency, other Defense Department facilities “routinely comply with.” 

Monaeka Flores, executive director of Prutehi Guåhan, said the military’s conduct amounts to “environmental racism.” She and other activists argue that U.S. territories such as Guam are subjected to environmental burdens that would be less politically acceptable in the States.

According to a Joint Region Marianas spokesperson, the command “provides information in accordance with applicable legal and regulatory requirements” and is coordinating with environmental regulators “in support of their regulatory responsibilities and the ongoing dieldrin investigation.” 

“Joint Region Marianas remains committed to providing regulators with accurate, verified information and communicating openly with the Guam community,” the spokesperson said.

Why Are My Friends Dying?

Tessa Robinson vividly remembers the day in 2008 when, living in San Diego, she got a call from her then-husband: They were moving to Guam. 

Chris, a Navy helicopter pilot, had received a permanent change of station order to Andersen Air Force Base. The assignment would last three years, and Robinson would be coming with him. 

“I was thrilled, honestly,” she said. “It seemed like a great time to go. We were relatively newly married, we were in our 20s, and we didn’t have kids yet. It felt like something to experience.”

Like many Americans, Robinson knew little about the island. She went to a bookstore and picked up a Lonely Planet guide to Micronesia, not realizing Lonely Planet was the publisher. 

“I just thought Micronesia was ‘the Lonely Planet,’” she said.

Guam is the largest island in Micronesia, a vast region of the western Pacific made up of more than 2,000 islands. It is home to the CHamoru people, whose ancestors settled there more than 3,500 years ago. Spain colonized Guam in the 17th century, and the United States took control in 1898 during the Spanish-American War. People born on Guam are U.S. citizens, but residents cannot vote for president and have no voting representation in Congress.

Soon after arriving on Guam, Robinson found herself alone on the other side of the world. 

“The deployment schedule was pretty tough,” she said. “Three weeks after we got there, Chris deployed [to Iraq] for the better part of 15 months.” 

The isolation can be difficult for military spouses, but Robinson forged lifelong friendships with the other women on the base. 

“You’re so far ahead in time zones that it’s difficult to keep relationships back in the States and tough to talk to your family from Guam,” she said. “And so these people really become your family.”

The housing itself left a lot to be desired. Many of the single-story duplexes were built in the late 1950s, with concrete walls, concrete slabs, and slightly pitched concrete roofs. 

“[They were] truly concrete bunkers designed to ride out the worst of weather because … typhoon season was always a real big deal,” Robinson said. 

The 750 residences were known as Wherry-Capehart housing, part of a Cold War-era federal program that produced relatively inexpensive military family housing at installations around the world. 

What Robinson didn’t know was what had been put beneath homes like hers.

Beginning in the 1950s, pesticides, including dieldrin, were commonly applied to soil beneath building foundations to keep termites and other insects out. Dieldrin and related organochlorine pesticides like chlordane and aldrin were also widely used in agriculture before concerns about their effects on human health and the environment led to increasing restrictions. 

Dieldrin breaks down very slowly in the environment and can persist in soil for years. It also accumulates in living organisms and can bind to dust particles, allowing wind to carry contaminated dust over long distances. 

The United States banned most use of dieldrin in 1970, with some termite-control applications continuing until 1987. 

Animal studies have linked exposure to neurological and reproductive effects and liver tumors, and the U.S. Environmental Protection Agency classifies dieldrin as a probable carcinogen.

Back then, none of that was on Robinson’s mind.

With their husbands deployed, the spouses found ways to entertain one another. One friend, Kate, missed Starbucks so much she invited the women over for coffee and tried to recreate her favorite drinks from the chain. 

When Robinson first arrived at Andersen, she heard that women living there were suffering miscarriages. Eventually her own friends began experiencing miscarriages and other reproductive complications. 

“It felt like more than what’s normal in a population of such a small group of people,” Robinson said. 

The women were mostly healthy and in their 20s, Robinson said. One friend, Natalie, experienced three miscarriages while living on base and another, Stacy, lost twins at 20 weeks. Another friend, Anet, gave birth to a baby, Gabrielle, who died two days later after complications involving her heart and lungs. 

“We all really grieved when they lost their baby,” Robinson said. 

After Robinson left Guam in 2011, more troubling news followed.

Some of the women she had known developed aggressive cancers at unusually young ages. Kate died of kidney cancer, and Anet died of ovarian cancer, both in their 30s. Robinson’s next-door neighbor, Jolene, was diagnosed with colon cancer. The person who later moved into Robinson’s former home, Bethany, was diagnosed with leukemia.

Robinson found the pattern difficult to dismiss.

She began wondering whether others who had lived at Andersen had similar experiences. 

In 2025, Robinson found an online survey created four years earlier by a former Andersen resident looking for other residents, aged in their 30s and 40s, who had lived there during the 2000s and later experienced serious or unexplained health problems. She circulated it through social media and military community networks. 

On social media, the survey gained more than 150 responses from people reporting aggressive cancers, reproductive issues, stillbirths, birth defects, and other illnesses.

The responses do not establish that conditions on the base caused those health problems. And the diagnoses have not been independently verified. The survey relied on self-selected respondents recruited online, meaning it cannot be considered a scientific study, either. 

But it did identify a previously unrecognized group of former residents who believed they had experienced serious health problems during or after living at Andersen. 

For Robinson, the responses reinforced her suspicion that something in the environment had played a role. 

“You can’t change my mind that it is not something environmental caused by something that happened [on Andersen],” she said. 

Former residents have proposed different explanations. Some pointed to mold in the ventilation systems. Others reported high levels of radon readings in their homes. A report from the Agency for Toxic Substances and Disease Registry found that by the early 2000s the military had renovated roughly half of Andersen’s housing in an effort to mitigate radon levels.

Robinson struggled to pinpoint a clear explanation—and with life pulling her attention elsewhere—her research stalled. 

Then, later in 2025, she heard about dieldrin for the first time in news reports about contamination at well Y-15 in Yigo. 

She immediately thought about the water she had used at home. 

“I made bottles with that water for my daughter and I drank it all the time,” Robinson said. 

Whether dieldrin played any role in the miscarriages, cancers, or other health problems reported by Robinson and her friends remains unclear. But research has documented reproductive and developmental effects associated with exposure to the pesticides used at Andersen. 

A 1971 study found increased stillbirths among dogs given aldrin orally for 14 months before mating. Aldrin converts to dieldrin in the body.

A study of women living in pesticide-treated homes found an association between residential treatment and dieldrin levels in breast milk. Researchers identified inhalation as a likely exposure route. Another study found measurable aldrin and dieldrin in indoor air years after homes had been treated.

Those findings deepened Robinson’s suspicion that families at Andersen had been exposed to a variety of environmental hazards.

While Robinson was living at Andersen, the Defense Department was investigating pesticide contamination around military housing on Guam.

A 2024 pesticide-management report prepared by military contractor GHD and released by Guam EPA through a records request summarized investigations conducted by Naval Facilities Engineering Systems Command housing in Guam and Hawaii between 2004 and 2010. Those investigations repeatedly detected aldrin, dieldrin, and chlordane “above screening levels” in soil around housing at Andersen Air Force Base. 

“The highest pesticide concentrations were found in soil samples collected beneath existing concrete slab foundations and immediately adjacent to the foundations of existing structures,” the report said. 

The report also said the chemicals may have been “routinely applied” and that residues could still be “present beneath and around structures that were treated prior to the mid- to late-1980s.”

The records raise questions about whether pesticides beneath some military homes could have migrated indoors. 

Decades earlier, the Defense Department had identified problems with heating and cooling ducts used in some Capehart housing. The ducts were installed in or beneath concrete slabs and made of inexpensive materials that deteriorated over time, allowing termiticides in the surrounding soil to enter the ventilation system. 

A 1981 report by the General Accounting Office, now known as the Government Accountability Office, described pesticide vapors entering military homes through the ducts. 

“In some cases the vaporization occurred to the extent that droplets condensed on uninsulated ceilings,” the report said. 

The government’s audit covered military housing in Virginia, Hawaii, and North Carolina. The following month, the Associated Press reported that the problem potentially affected about 31,000 military housing units built during the previous 25 years. 

Attempts to fix the problem were not always successful. The GAO found that the Air Force spent $2.9 million sealing or replacing ducts in 1,259 housing units, but pesticide vapors persisted in some homes. 

“When the new ceiling ducts were used, the vapors, which had penetrated the units’ surfaces for up to 25 years, were again present and were believed to be emanating from the units’ interior surfaces,” the report said.

Responding to the survey of former residents, JRM said it “takes concerns regarding pesticide-impacted soil and the health of current and former Guam residents seriously.”  

“The presence of pesticides in soil, however, does not by itself establish that the chemicals entered drinking water, migrated into former residences or resulted in human exposure,” the JRM spokesperson said. 

These publications asked JRM if it knew whether the duct issue affected Capehart housing on Andersen, but it could not confirm.  

“Joint Region Marianas has not identified information confirming that the condition described in the 1981 General Accounting Office report affected former Capehart housing at Andersen or that corrective actions were required or taken,” the spokesperson said.

A Long History of Contamination

The U.S. military’s legacy of contamination on Guam is difficult to ignore. What is much harder to establish is a direct link between specific pollutants and disease among people who lived on the island.

Veterans who served on Guam long alleged that Agent Orange had been used and stored there, claims U.S. officials did not acknowledge for decades. Mounting evidence eventually contributed to the PACT Act of 2022, which expanded benefits for veterans, including those exposed to herbicides in Guam and other Pacific locations.

Families on Guam have long suspected that generations of cancer diagnoses may be connected to environmental contamination. Lawyer and author Julian Aguon, who lost his father to pancreatic cancer, said that “if you are CHamoru, you are always coming back from burying the dead.” 

Overall cancer incidence on Guam is lower than in the mainland United States, but some types occur at higher rates or at younger ages. 

One of the few studies to examine a possible link came in 2011, when an epidemiologist found a possible association between a polychlorinated biphenyl spill from a former U.S. Coast Guard facility and a long-term increase in proportional cancer mortality in a nearby village whose residents relied on the affected lagoon for fishing. A fish consumption advisory remained in place as of March 2025.

Andersen Air Force Base presents another longstanding contamination problem. The base sits above Guam’s sole source aquifer and was placed on the U.S. Environmental Protection Agency’s National Priorities List in 1992 because hazardous substances, including PCBs, pesticides, metals, fuels, and industrial solvents, were found in places including unlined landfills and chemical storage areas. 

The U.S. Army Corps of Engineers has described the aquifer as “particularly vulnerable to contamination” because pollutants can move through the island’s porous limestone into groundwater. 

The federal government has rarely paid damages for environmental harm tied to military activity in the Pacific. A major exception came in 2023, when the government of Guam reached a $48.9 million settlement with the United States over the Ordot dump, where the military had disposed of hazardous waste from World War II. 

The attorney general who brought the case was Leevin Camacho.

Military Housing ‘Possible Source of Dieldrin in Drinking Water’

The Ordot dump case had felt personal. But contaminated water flowing through Camacho’s family home hit even closer. 

Pursuing justice wasn’t optional, he joked—his mom made sure of that. 

“In all honesty, my mom won’t let the issue go,” Camacho said. “She’s been very forceful about me doing something [about the dieldrin issue].” 

After the September 2025 revelation of dieldrin in the drinking water, Camacho began laying the groundwork for what could become one of the largest government claims in Guam’s history, seeking hundreds of millions of dollars from Guam EPA and the Guam Waterworks Authority.

Internal emails obtained by Camacho and reviewed by The Margin and The War Horse showed that by October 2023, the U.S. Environmental Protection Agency was threatening federal enforcement action against the water authority over dieldrin contamination. 

The records also showed that the U.S. EPA had alerted Guam EPA to elevated dieldrin levels as early as 2012. But years passed before federal inspectors returned in 2022 and again pressed the local agency to act. 

One complication was that dieldrin is not federally regulated as a drinking water contaminant. There is no nationwide enforceable limit for how much dieldrin can be present in drinking water, and detections were not appearing in Guam EPA’s routine monitoring summaries, according to an internal email. 

Guam EPA eventually developed its own limit on dieldrin levels, which took effect in August 2025 after a two-year review process. That threshold triggered a do-not-drink advisory for well Y-15. 

For the previous seven months, dieldrin concentrations in the well had averaged 1.75 micrograms per liter—more than eight times above Guam EPA’s new limit of 0.2 micrograms per liter. 

By October 2025, Guam EPA had begun investigating where the contamination might be coming from. After Joint Region Marianas announced that water on base was safe, regulators obtained two reports from military contractors: a 2024 pesticide soils management plan by contractor GHD and a 2024 soil-sampling report by Naval Facilities Engineering Systems Command. 

Those records revealed a yearslong effort at Andersen Air Force Base to excavate and relocate pesticide-contaminated soil.

The plan noted that pesticides can become more volatile in hot environments, increasing the risk of inhalation. It also identified dust as a concern for construction workers and nearby residents and called for control measures, including upwind and downwind air monitoring. 

The documents released by Guam EPA included a letter from Pacific Rim Constructors, dated July 16, 2025, notifying the environmental regulator that it planned to begin “encapsulation activities.” But, internal records suggest, the agency first became aware of the notification letter in October and had no prior knowledge of the contaminated soil excavation.

That raises questions about whether the environmental regulator was notified about the nature of the construction activities. In an emailed statement, a spokesperson at Guam EPA said the agency was prohibited from sharing or divulging information on whether it had received Pacific Rim's notification letter in July 2025. The U.S. EPA said it first learned of the military’s soil sampling and management activities in the Fall of 2025. Pacific Rim Constructors did not respond to our questions. 

How far over the line

Highest detected dieldrin under each of the ten most contaminated units, as a multiple of the 2.5 mg/kg screening level. Building 1173, where the report also found aldrin at 25 times its level, leads.

Guam EPA staff began in November 2025 discussing the need for project-closure reports and additional data to determine whether contaminated soil at Andersen could be contributing to dieldrin in groundwater, according to an email obtained under the Sunshine Reform Act. 

In December 2025, Guam EPA administrator Michelle Lastimoza asked the U.S. Environmental Protection Agency in an email whether it had recent groundwater-monitoring data for “dieldrin hotspots” at Andersen Air Force Base. 

EPA Superfund manager John Chestnutt responded that the agency had not received any such data and questioned whether the military’s expedited September testing had examined the areas most relevant to the investigation. 

“Not sure if the sampling included any monitoring wells closer to the area of interest,” Chestnutt wrote. “I’m not aware that those results are validated yet and that they’ve been released.”

A Joint Region Marianas spokesperson said the command provided Guam EPA with detailed reports of the September testing. 

“The characterization that Joint Region Marianas conducted drinking-water testing to deflect responsibility for dieldrin detected in Guam Waterworks Authority Well Y-15 is incorrect. Because of the Y-15 results, JRM accelerated planned testing of military drinking water wells to ensure public safety,” the spokesperson said. “It was not designed to determine the source of dieldrin in Y-15 and did not replace a source investigation.”

On Dec. 23, Guam EPA and U.S. EPA formally asked Joint Region Marianas to investigate potential sources of dieldrin contamination on the base. 

The agencies cited findings from the military’s own project reports and wrote that dieldrin contamination remained “unaddressed.” 

“Given that the former housing units may be a possible source of dieldrin in drinking water, the stated goal to maximize the reuse of PIS [pesticide infected soils] on-site may need to be reevaluated,” the letter said. 

Five days later, on Dec. 28, Rear Adm. Brett Mietus responded that he would consult with his legal and environmental staff in January about how to proceed.

Guam EPA held a town hall at a Yigo gymnasium on Feb. 25, drawing dozens of residents concerned about the dieldrin contamination. 

Before the meeting, John Salas, environmental director at Naval Facilities Engineering Systems Command Marianas, the command that had previously investigated pesticide contamination in the soil on Andersen, emailed Guam EPA senior science advisor Capt. Elizabeth DeGrange to say the military would be “tracking” the event but would “unfortunately” not attend in an official capacity. 

Salas wrote that Rear Adm. Brett Mietus had “emphasized the importance of ensuring our messaging is properly coordinated and synchronized.” He also provided a prepared statement from Mietus that again distanced Andersen from contamination.

“At this time, no data has identified a specific origin,” the statement said, “and any decisions regarding response actions will be guided by verified findings and applicable environmental regulations.”

The town hall was tense. Residents, including Camacho, pressed Guam EPA officials over why the community had not been told about the contamination sooner. 

During the meeting, Capt. DeGrange said the request for Joint Region Marianas to investigate potential dieldrin sources at Andersen was “not a sign of guilt,” according to the Pacific Daily News.  

In response to the newly released emails, Camacho said the community has reason to question whom Guam EPA is “actually working to protect."

In an email statement, Guam EPA administrator Michelle Lastimoza said her agency “is committed to protecting public health and the environment.”

“We know that dieldrin was once legal and widely used across the island by both military and civilians, and it is extremely persistent in soil,” Lastizoma said.  

Lastimoza said the Air Force’s soil management plans were “the best known handling of pesticide-impacted soils.” She said the regulator was conducting a thorough investigation of potential sources of contamination in well Y-15, including a joint assessment with the military to “explore potential sources both inside and outside the fence.”

Lastimoza said the regulator welcomed any additional information in their continuing investigation. 

“If a responsible party can be determined, Guam EPA intends to hold that party accountable,” Lastimoza said. “We cannot, however, act on rumors and suspicions.” 

Guam EPA declined to release details of the joint assessment in response to a public records request, saying it was controlled unclassified information that could only be released by the Defense Department. 

But communications between Guam EPA and Joint Region Marianas provide clues about where investigators are looking. The records suggest the inquiry is focusing on several underground injection-control wells and a stormwater drain that may receive runoff from the housing area and discharge into the Y-15 catchment. 

Emails also show that Guam EPA was still seeking potentially relevant information from the military months after they began investigating potential dieldrin sources in October 2025. 

On March 9, Joint Region Marianas sent DeGrange a contaminated-soil closure report covering phases 1 through 3 of the housing project. 

Then, on June 15, DeGrange told a U.S. EPA Superfund manager that “there’s rumors that maybe JRM isn’t sharing all of the data that they already have.”

U.S. EPA spokesperson Alejandro Díaz said the environmental regulators had made “numerous requests” to JRM for pesticide sampling data relevant to the housing project. 

“JRM has indicated they are gathering and will be transmitting available data,” Díaz said. 

Díaz said the EPA was working “collaboratively” with JRM to fine tune the investigation. 

“We understand JRM has completed contract negotiations and plans to award the contract for this work in September 2026,” he said.

The Defense Department has not yet fulfilled public records requests for additional records concerning how pesticide-contaminated soil at Andersen was handled and whether it could have contributed to contamination in Yigo’s drinking water supply.

Groundwater contamination expert James Connors, a hydrologist and geoscientist with the American Institute of Hydrology, said the combination of pesticide-contaminated soil, construction activity, and Guam’s tropical environment created the perfect conditions in which contaminants could readily reach groundwater. 

“It’s almost all of the worst case conditions for this type of contamination,” Connors said. “A Pacific Island with a high rainfall, with a thin veneer of soil sitting on top of a limestone aquifer ... can make contaminants move very quickly.”

The Air Force has known for decades that disturbing pesticide-contaminated soil can create risks. 

In 2005, it urged the city of Victorville, California, to halt demolition of former military housing at the decommissioned George Air Force Base because of what it described as “pervasive” dieldrin and aldrin contamination. 

“The pesticides could present a risk to human health if soils are inhaled, ingested, or contacted by skin,” the Air Force wrote.  

Records also show that pesticides had been detected in Guam’s drinking water long before the housing redevelopment project began in 2016. 

A 1996 newspaper op-ed quoted a Guam Waterworks Authority official describing pesticides in the drinking water as “a real concern.” 

“If we don’t develop a plan to analyze the effects on our permanent water supply and aggressively follow through with that process, we may be sitting on a time bomb that will destroy our most precious resource,” the op-ed warned.

Historical water monitoring data obtained by Camacho from Guam EPA shows one reading at well Y-15 that was analyzed twice, with a dieldrin concentration of 1.3 and 1.7 micrograms per liter in October 2008—nearly identical to the average concentration that would prompt a do-not-drink advisory 17 years later. 

Connors said one possibility is that the dieldrin reapplied around the house perimeters was carried by rainfall from the soil into the aquifer before construction ever began.

What decades of exposure may have meant for residents’ health is much harder to determine.

The Margin and The War Horse spoke with Yigo residents who are now questioning whether contaminated drinking water could have contributed to the deaths of loved ones. 

“I was drinking the tap water all my life,” said Yigo Vice Mayor Pedro Blas, who was born in 1996. “We thought it was safe.” 

Blas was 9 when his mother died after a long battle with cancer.

“I can’t help thinking it was when she moved to Yigo, and she started drinking the tap water that she became sick,” he said. 

Rosita Taitano Huff, Camacho’s aunt, similarly wonders whether health issues she experienced could have been related to dieldrin. 

“I’m really sad because at that time we didn’t know what was wrong with me,” she said. “Even now I get paranoid. I still go buy water.” 

She is particularly angered that hundreds of children attending nearby Upi Elementary were exposed to contaminated drinking water. 

“You don’t know what’s going on with your brains when you start ingesting all those chemicals,” Huff said. 

A treatment system has since been installed at well Y-15, and the do-not-drink advisory has been lifted. 

This year, Camacho has helped residents file roughly 470 claims against the Guam Waterworks Authority and 250 against Guam EPA, each seeking as much as $500,000 in compensation. 

“One of the goals is to push this litigation to force Guam EPA and the governor of Guam to actually take legal courses against the responsible party, which is the Department of War,” Camacho said. 

Administrator Lastimoza said the $500,000 figure “reflects statutory limits under the Guam Government Claims Act rather than being based on any assessments of actual or potential harms.” The Governor of Guam’s office and the GWA did not respond to our questions. 

Blas says that for the community, determining who is responsible matters less than finding out what years of exposure could mean for the people who relied on the water.

He said residents do not want this issue “swept under the rug like a lot of other things on this island.” 

“They want to know if their health has been compromised and if their life has been shortened by simply brushing their teeth,” he said. 

***

Your donation supports in-depth reporting, data analysis, data visualizations, and original photography. Join us in the fight for environmental justice by contributing today — every dollar helps us tell the stories of the people and communities who have been and are currently experiencing injustice.