A January 2021 tip to AP investigative reporter Jason Dearen put him in touch with a foreign service officer who had contracted a fairly rare form of cancer and believed her illness was caused by polluted water at Fort Ord, an Army base on the central California coast where she’d lived for years in the 1990s. That launched a yearlong investigation into the consequences of toxic contamination at the base, which is on the Environmental Protection Agency’s list of the most polluted places in the nation.

Dearen started researching the base and reached out to investigative team colleagues Martha Mendoza and Juliet Linderman. Realizing the scope of the complex story, the team split up the reporting duties: Mendoza would spend time at the decomissioned base and dig into thousands of pages of public documents about its history and toxic legacy. Dearen would find epidemiological and/or medical studies that had been done on linkages between the toxins at Fort Ord and disease. Liinderman would talk to the people who’d lived there and gotten ill.

Dearen found that the only scientific assessment of public health risk at the base was a 25-year-old study by the Centers for Disease Control and Prevention that relied entirely on the Army’s own water quality data instead of independently collected samples. The study found no “likely” harm from the site, either in the past or in the future, but Dearen spoke with multiple epidemiologists who found flaws in the study and the CDC’s conclusion. One major contaminant, trichloroethylene, or TCE, is now identified as a carcinogen.

Meanwhile, Mendoza found documents with clear and convincing evidence that the contamination was worse than the Army had publicly acknowledged. The documents showed that the Army knew that TCE and other toxic chemicals had been improperly dumped at Fort Ord for decades. a 1985 military memo showed that contractors brought in to clean up the groundwater in the 1980s were warned not to tell community members, news media or local public agencies what they found in their drinking water. Mendoza also spoke with a man who’d worked at the base’s airport, the site of a burn pit where chemicals were set afire regularly, who shared his own trove of documents including videos and transcripts of public meetings where the Army downplayed risks of the contamination.

Linderman conducted many in-depth interviews with foreign service officer Julie Akey who has spent years collecting names of people who lived at Fort Ord and were later diagnosed with cancers; all filed claims with the Department of Veterans Affairs that had been denied based on that old CDC study’s suspect findings. Linderman accompanied Akey to doctor’s visits and talked with her physician about what possible causes there could be for her cancer, multiple myeloma. She collected medical and other health documents from each veteran she interviewed, uploading them to the AP team’s Google Drive.

At the same time, AP investigative video journalist Serginho Roosblad began accompanying Mendoza on her many trips to Fort Ord. He combined drone footage with images shot by freelancers Noah Berger and Nic Coury, along with archival footage. AP’s Marshall Ritzel collaborated to add graphics and animation to what became a powerful short documentary about Fort Ord’s toxic legacy, and Washington photographer Patrick Semansky made photos of Akey at her Virginia home.

The body of evidence uncovered by the reporters raised questions about the VA’s use of the decades-old study to deny benefits, and pointed to the need for a new epidemiological study as well as a new look at the still-present chemical pollution at Fort Ord, which is now home to a small public university. Million-dollar homes are being built across the street from the Superfund landfill cleanup.

Former White House Chief of Staff and Defense Secretary Leon Panetta told Mendoza the military is abandoning communities, leaving huge messes to clean up. “I think that (individuals suffering illness) have every right to ask the question whether or not whatever physical ailments they may have was in part due to the failure to provide proper cleanup,” Panetta said.

Reaction to the team’s story was immediate. Military news outlets jumped on it, publishing the entire 3,500-word piece, an NPR affiliate station in central California is organizing a community forum with Panetta and Mendoza, and two U.S. representatives from California called on the federal government to study whether there’s evidence that the potential toxic and contaminated drinking water can be tied to specific cancers and other diseases.

And the White House has since reached out to AP to ensure that one of the reporters would be on a briefing about new actions around burn pits and other contaminants.