Sixteen miles northwest of Denver, elk and deer roam a windy mesa. Cottonwoods flag mild waterways. The land appears pristine, but the aura of untouched nature is an illusion: Plutonium and other radioactive material from this area’s former occupant, a nuclear bomb parts factory called the Rocky Flats Plant, still lurk in the soil. This past September, about two miles away, a group known as the Rocky Flats Stewardship Council, which consists of local government officials and community members, discussed the conditions at the site. The council was formed in 2006 to oversee post-closure management of Rocky Flats, the majority of which has been converted into a national wildlife refuge.

The council’s work often goes unnoted, and many of the management activities surrounding Rocky Flats are routine. A convergence of recent events, however, has again generated public interest in the site of the factory, which ceased plutonium operations in 1989. Residential projects such as Candelas rise just beyond the property line, and refuge managers plan to control vegetation with burns. Moreover, members of the public have access to the refuge for the first time. Guided tours began last summer, and the area, which for more than 60 years was closed to the public, is scheduled to welcome visitors by the end of 2017 for unsupervised activities such as hiking and biking.

The advent of recreation at Rocky Flats was a point of contention at the September council meeting. Officials with the Department of Energy (DOE), the federal agency that controls an off-limits former industrial area at the center of the property, and the U.S. Fish and Wildlife Service, which manages the refuge, acknowledge activities at the former plant left hazardous substances such as plutonium in the ground. The question today is one of risk: Is it safe for humans to walk through Rocky Flats and to live nearby? At the meeting, Carl Spreng, a state public health official, assured the board that health risks at Rocky Flats are “extremely low.” To make his case, he cited extensive research data, including millions of records and more than a million soil samples.

Nuclear weapons plant worker in 1987
A factory worker at the nuclear weapons plant in 1987. —Denver Public Library, Rocky Mountain News photo archives

After Spreng had presented his evidence, a pair of activists spoke and laid out a case against public access to the refuge. One of the speakers was Anne Fenerty, a Boulder resident and trained chemist. The other was a 61-year-old man named Jon Lipsky, who, for the past two years, has been a familiar presence at forums concerning the defunct factory. Lipsky is tall and retains a formidable build, and he projects affability and intelligence. He’s at ease in front of an audience, and when he gives presentations about Rocky Flats, he exudes both an exhaustive grasp of the subject and a public speaker’s ability to stay on message.

With the air of a whistleblower exposing a cover-up, Lipsky told the council that “present controls do not protect human health and the environment and in fact threaten human health on the refuge.” He suggested that the Environmental Protection Agency (EPA) and the Colorado Department of Public Health and Environment—the agency that employs Spreng—had withheld evidence of health risks from the public. Lipsky also directly challenged an assertion made to the council in April 2015 by Scott Surovchak, the DOE’s Rocky Flats site manager, who said the refuge is safe for unlimited use. “Public access,” Lipsky said, “should not be allowed.”

Lipsky’s words crackled with historical authenticity and authority: In 1989, as an FBI agent, Lipsky led a raid on the Rocky Flats Plant as part of a criminal investigation. It was the first time the FBI raided another federal agency.

Resistance to power is a trait Jon Lipsky exercised early in life. As a teenager in Anaheim, California, his high school football coach wanted him to play center, but Lipsky protested that he preferred tight end. One day, Lipsky recalls, the coach complained he wasn’t hitting the practice bag hard enough. “So he grabbed the bag and told me to hit it, and I knocked him on his ass,” Lipsky says. “That day was a defining moment; I think he saw that I could block.”

Lipsky was the second of four children. His father worked for Firestone Tires, among other companies, and his mother took care of the home. Lipsky was a C student; he preferred sports to academics. He also had a strong sense of justice. It offended him when two teammates were caught with marijuana but escaped serious repercussions because of their roles as athletes. Lipsky’s father had moved to the United States from Canada in the late 1940s. He remembers his old man talking about the FBI, about how he thought it was “a really good organization,” and that’s what encouraged Lipsky’s interest in the agency. “He felt that if you’re going to do something,” Lipsky says, “be with the best.”

In 1972, just after he graduated from high school, Lipsky landed a job as a clerk for the FBI. That fall he attended night school at Fullerton College, where a left-leaning history professor learned Lipsky worked at the bureau; the teacher asked to see Lipsky after class one day. “He told me he was going to do everything he could to fail me out of school,” Lipsky says. The teacher’s words didn’t worry Lipsky, who was aware of some of the objectionable practices of that era’s FBI. He viewed the essential mission of the FBI as just, and he intended to fulfill it without allowing the bureau to turn him into what he calls “a drone” for misdeeds.

Lipsky later studied police science and eventually earned a bachelor’s degree at California State University, Los Angeles. After a five-year stint as a Las Vegas cop, he returned to the FBI as a special agent in 1984. His first daughter (he has three, and two granddaughters) was born in Nevada two days before he graduated from the FBI Academy in Quantico, Virginia. Shortly after Lipsky became an agent, the bureau assigned him to work environmental cases out of its Denver office. By then, metro area residents had begun to view the Rocky Flats Plant with suspicion. Lipsky’s wife had read about the factory, and the couple decided to pass over Denver and purchase a home in Aurora, far away from the plant. Still, even though he was professionally attuned to environmental work, Lipsky had no reason to believe Rocky Flats was violating hazardous waste laws. Obscurity buffered the plant from the day it opened.

Aerial view of Rocky Flats in 1995
An aerial view of Rocky Flats in 1995. —Denver Public Library, Rocky Mountain News photo archives

The federal government announced in 1951 that it would build Rocky Flats, and the plant went into full production two years later. The site occupied more than 6,000 acres, but most of the area was left open to insulate a centralized 385-acre industrial area.That Rocky Flats was part of the country’s nuclear-bomb-making network was a matter of public record, but the details of its role were kept secret; rumors suggested the factory produced everything from cleaning supplies to glass doorknobs. As is well-documented today, its main purpose was to manufacture plutonium pits: spheres of plutonium that detonate blasts when combined with thermonuclear components. Most of the estimated 7,100 nuclear warheads still in the United States’ possession contain pits from Rocky Flats.

In the plant’s first decade, few restrictions governed the handling of hazardous waste. Accidents and pollution were persistent at the factory. Radioactive material was often simply buried in the ground. On September 11, 1957, when the plant was operated by DOE contractor Dow Chemical Company, a plutonium fire in the main production building, known as 771, launched radioactive particles into the air. One study later concluded that strong winds likely blew plutonium more than a dozen miles to downtown Denver. Another plutonium fire that erupted on Mother’s Day in 1969 was considered the costliest industrial accident in United States history at the time. That mishap inspired the first dogged anti–Rocky Flats activism. Independent scientists began to report high concentrations of plutonium east of the plant and suggested downwind contamination could be linked to increased cancer rates (a direct connection is difficult to prove). The 771 facility later became known as the most dangerous building in America.

Lipsky arrived in Denver at an opportune time to work environmental crimes. The Resource Conservation and Recovery Act (RCRA), which governs the disposal of solid and hazardous waste, became law in 1976. The act gave hazardous waste handlers until late 1980 to officially declare themselves to the federal government. Lipsky, who was appointed the FBI’s regional EPA liaison, seized on the RCRA filings. He viewed the documents as a stack of leads. “I wanted to see who the polluters were,” Lipsky says. Surprisingly, according to Lipsky, almost 30 percent were federal entities—one of which was Rocky Flats. “I thought, Holy cow. I had no idea,” he says. “Up until 1980, I don’t think we really knew the extent of the manufacturing operation out there.”

Working closely with an EPA counterpart, William Smith, Lipsky’s initial targets were private operators, such as Frankel Manufacturing Company; the business eventually pleaded guilty to storing more than 1,000 kilograms of hazardous waste without a permit.In 1987, a federal grand jury found that Denver’s Protex Industries, which Lipsky helped investigate, had placed three employees at risk of serious bodily injury or death by exposing them to toxic chemicals. It was the first conviction under RCRA’s “knowing endangerment” provision.

Though the EPA collaborated with the FBI on such investigations, Smith considered the bureau “a two-headed monster” that he tolerated for the money and resources it could throw at big cases. At first, Smith viewed Lipsky as an inexperienced and overeager investigator who sometimes chased down leads the EPA had already rejected. According to Smith, Lipsky once showed up at the EPA’s National Enforcement Investigations Center in Lakewood with a mayonnaise jar full of hazardous material he’d retrieved from a suspect site by digging through the garbage. “He went dumpster diving, which is insane,” Smith says. “You don’t go to a chemical facility without at least level-B protection…. I was just like, ‘Jon, you shouldn’t do that.’?” (Lipsky says he does not recall this incident.)

Despite occasionally unorthodox approaches, Lipsky quickly earned a reputation as one of the top FBI environmental crime investigators in the country. And three years into the job, he launched one of the largest and most important cases he would ever take on—one he’s still pursuing as a civilian almost 30 years later.

In 1987, Smith shared an unsigned government memo with Lipsky that contained talking points on negotiations happening between the EPA and the DOE over Rocky Flats. The document, which was sent to DOE official Mary L. Walker, stated that some of the plant’s waste facilities were “patently illegal” and that recent good press had “taken attention away from just how really bad the site is.” That memo marked the beginning of Lipsky’s Rocky Flats investigation.

In December of the following year, after more than 12 months of research, Lipsky made clandestine nighttime flights over the plant using infrared technology. What he saw suggested Rockwell International, which had succeeded Dow in managing the plant, was using an incinerator in building 771. The incinerator was supposed to have been shut down a few months earlier, by order of the government, for safety concerns. By the summer of 1989, investigators believed they had accumulated enough evidence against Rocky Flats to seek a search warrant. On a Tuesday morning in June of that year, Lipsky visited a federal magistrate, who’d received an affidavit more than 100 pages long the previous day. The document alleged Rocky Flats had violated multiple environmental laws between 1980 and 1988 and that “Rockwell and Energy Department officials have knowingly and falsely stated Rocky Flats’ compliance” with the law. The judge signed a search warrant. With dozens of FBI and EPA investigators on standby, Lipsky arrived at Rocky Flats under the pretext that he was visiting the plant for an ecoterrorism briefing. Instead, he led a government raid of the plant.

Lipsky quickly ran into unexpected obstacles. In the first hours of the raid, he discovered that Earl Whiteman, the top DOE manager at Rocky Flats, had been transferred away from the plant about a month earlier. Lipsky found the timing suspicious, as if Whiteman had been tipped off. Days into the raid, U.S. Attorney General Dick Thornburgh ordered the search warrant affidavit unsealed, an unusual move Lipsky says gave Rocky Flats managers “the road map of what we were looking for and a big place to hide it.” He adds, “It was a betrayal.”

Heavily armed DOE guards patrolled the plant, and Lipsky became anxious about his safety. He says a white SUV tailed him around the property. He even checked out a shotgun from the FBI office as a precaution. Tips poured in during the raid, including an allegation that workers burned plutonium–contaminated waste in the incinerator building at night. Lipsky and Smith attempted to filter the credible from the ridiculous, such as reports of two-headed fish in Standley Lake. Smith says Lipsky too often failed to dismiss bunk information, which resulted in the team chasing down each and every lead.

A federal special grand jury was convened in Denver to consider the case, and Lipsky testified. What he said isn’t publicly known because grand jury testimony is kept secret. But Lipsky has since stated that the evidence from the investigation and the raid demonstrated that Rockwell flouted federal law in disposing of hazardous waste. Federal prosecutors cut the investigation short, sent the jurors home, and negotiated a deal for Rockwell to plead guilty to hazardous waste and Clean Water Act crimes. The contractor was fined $18.5 million, and no individuals were charged.

The outcome disappointed Lipsky in part because the investigation was never completed. He wasn’t the only one unsatisfied. U.S. Representative Howard Wolpe, a Michigan Democrat, was concerned enough to convene a House subcommittee hearing on the matter—and subpoenaed Lipsky to testify. Lipsky says a Justice Department lawyer cautioned him against telling Congress that there was evidence against individuals involved with the Rocky Flats case, but that’s what he told the subcommittee anyway. Three months later, the FBI transferred Lipsky to a squad that worked violent street gangs in South Central Los Angeles.

By this point, Rocky Flats had already been designated an EPA Superfund site. The DOE estimated it would take 65 years and more than $37 billion to clean up the former plant. Broomfield-based contractor Kaiser-Hill Company proposed a plan to do the job quicker and cheaper. Ten years and around $7 billion later, in October 2005, the government declared the Rocky Flats cleanup complete. The DOE transferred most of the land, except for the more pervasively contaminated central industrial area, to U.S. Fish and Wildlife for use as a wildlife refuge.

As for Lipsky, he stuck with the FBI until 2004. After he retired from the bureau, Lipsky started his own private investigation firm in Lake Forest, California, and named it Mission Accomplished Investigations. Even from the West Coast he maintained a role in Rocky Flats–related matters. He worked with the authors of The Ambushed Grand Jury, a book that chronicled an alleged cover-up by the Justice Department in the Rocky Flats case. And in 2005 he testified in a class-action lawsuit against Dow and Rockwell known as the Merilyn Cook case, which was filed by property owners in the vicinity of the plant and alleged that contamination from Rocky Flats constituted an “unreasonable and substantial” nuisance under state law. Lipsky says the FBI tried to dissuade his participation, that an agency liaison called him and said, “You aren’t going to be on that witness list, you aren’t going to testify.”

The four-month trial resulted in an award of around $1 billion for about 13,000 property owners. The case has since churned through years of appeals; Dow and Rockwell have asked the U.S. Supreme Court to hear the case, and the court could announce whether it will take it as early as this month.

In the summer of 2014, the Arvada Center for the Arts and Humanities, a venue that happens to sit downwind from the former plant, hosted a multiday event to commemorate the 25th anniversary of the Rocky Flats raid. The event included a keynote panel discussion, and in the moments before it began, the three panelists—former Governor Roy Romer and former U.S. Representative David Skaggs, who were both in office during the raid, and Lipsky—mingled backstage. One of the men secretly recorded the conversation.

The event marked the first time Lipsky had met Romer, who had not been informed of the raid before it happened. Their conversation reportedly became heated, and in the days that followed, word about the surreptitious recording spread and there was speculation about the taper’s identity. Skaggs told journalist Len Ackland of High Country News that the taper “was presumably looking for some kind of ‘gotcha’ event.” The Arvada Police Department opened a criminal eavesdropping investigation, and a detective interviewed Lipsky, who, according to a police report, was cagey about his involvement. During one of our several conversations earlier this year, Lipsky admitted publicly for the first time that he recorded the conversation. (The police dropped the case for lack of reasonable suspicion that a crime had been committed.) Lipsky says he made the recording for “historical” purposes. Although no gotcha moment was captured on the tape, the episode is evidence that, a quarter-century later, Lipsky was still on the Rocky Flats case.

In the decade after he testified in the Cook case, Lipsky continued to hunt down documents and communicate with other advocates. Around the time of the Arvada Center event, Harvey Nichols, leader of the Rocky Flats Technical Group, an activist organization, invited Lipsky to tackle a project that seemed precisely tuned to his talents: searching and scanning material from a vast Rocky Flats–related archive at the University of Colorado Boulder’s Norlin Library.

Candelas housing development near Rocky Flats
One of many homes in the Candelas housing development, some of which are located close to the Rocky Flats wildlife refuge

Lipsky and his wife moved to the Front Range from Southern California so he could work on the project, the goal of which is to publish documents from the archive online and make them publicly accessible. Nichols—a CU professor emeritus of biology who, at the behest of the government in the 1970s, studied airborne movement of particles from Rocky Flats—says Lipsky’s research at Norlin could help the Rocky Flats Technical Group secure grants to fund its work. Members of the group are active in almost every area of the Rocky Flats debate, including public recreation, controlled burns, and the reliability of government information. “We have a state health department that’s chronically weak on this,” Nichols says.

Lipsky has already shared some of his findings with other activists, including Terrie Barrie, whose husband worked at Rocky Flats. Barrie is involved in an effort to expand the class of Rocky Flats workers who are eligible for automatic government compensation if they have certain types of cancer. “I called Lipsky to see if he had any documents we could use to support the petition,” Barrie says, “and he was more than willing to help.”

Last year, Lipsky joined an outcry that swelled in response to a U.S. Fish and Wildlife proposal to manage vegetation at the refuge through controlled burns. Opponents argued that the burn, which was eventually called off, would spew radioactive smoke into nearby neighborhoods. Lipsky helped persuade a state commission to commit to holding a special meeting if federal managers return with a new burn proposal—and they almost certainly will. Refuge manager David Lucas says unchecked vegetation is wildfire fuel, and nonburn management methods, such as grazing, are less efficient. What’s more, he says, fires are natural. Since 1993 at least a dozen fires, some due to lightning, have scorched refuge land. “You can’t postpone the inevitable,” Lucas says. “I would rather burn it on our terms.”

Lipsky also argues—as he did during the stewardship council meeting last year—against allowing the public to access the refuge. He’s called for new, independent studies of contamination on the land. U.S. Fish and Wildlife, on the other hand, hopes to install a new parking lot, restrooms, and trails at the refuge by the end of next year, after which the area would be opened to unguided public use. Plans call for a trail to run from the top of the refuge along the northeast corner to a point by the former plant’s east entrance on Indiana Street. Although plutonium readings here fall well below the standard considered safe by the government, studies of this area have cited measurements that are above the average level for the refuge.

Laws that govern the grand jury process and federal investigations limit what information Lipsky can disclose. But he’s also discovered a lot about Rocky Flats as a civilian, information that’s not protected. What he’s learned in each of these phases of his life overlap here and there, making for a legal gray area when the former FBI agent discusses Rocky Flats. It’s a situation that means Lipsky is never quite sure when some government lawyer might allege that he has revealed protected information. He’s concerned that his efforts will land him on the no-fly list, and he wonders if someone is listening in on his conversations. Real or imagined, Lipsky’s fears made him reluctant to talk about his activities at Norlin Library; he worried that discussing his work publicly might tempt the DOE to somehow shut him down. I found a purported copy of a report written by the Rocky Flats grand jury online and sent a link to Lipsky asking if it was authentic. He refused to verify it. When I asked which individuals he thought should have been prosecuted after the raid, he replied, “I’m afraid if I were to give you the answer and that was printed, then they’d come to you, and they’d come for that”—and pointed to my cell phone as it recorded our conversation.

Still, despite his fears, Lipsky’s understanding of how hazardous waste was handled at the bomb factory compels him to try to force public revelations and to spread awareness about information that’s already been revealed. Simply stated, his argument is that state and federal officials are downplaying the risks to human health at Rocky Flats.

His public criticisms of government officials have earned him deep admiration among peers. “He’s very brave,” says LeRoy Moore, a Rocky Flats activist since the 1970s and a founder of the Rocky Mountain Peace and Justice Center (RMPJC). Noting Lipsky’s transfer to the LA gang unit, Moore added, “He’s paid dearly for that behavior.” In 2013, the RMPJC named Lipsky a Peacemaker of the Year. Last year, the Alliance for Nuclear Accountability honored Lipsky as a leader of “the movement for responsible nuclear policies.” Fellow activists say Lipsky contributes an unmatched breadth of knowledge to their work. His identity as the FBI agent who led the Rocky Flats raid grants him a certain celebrity status. When Lipsky accompanied activist Fenerty to a stewardship council meeting early last year, others who were present took note, Fenerty says. “I think it caused quite a stir. Everybody knew who he was.” She compares Lipsky to environmentalist Rachel Carson. “I consider Jon Lipsky in the same category,” she says. “An American hero.”

This vision of Lipsky, however, is not universal. Spreng, the state public health official, says study upon study contradicts Lipsky’s claim that the refuge is dangerous. The average concentration of plutonium on the property “equates to an excess cancer risk below one in a million for any exposure scenario,” Spreng says, adding that his agency and the EPA concur that the refuge could be available for “unrestricted use and unlimited exposure.” Spreng also says, “The attention by the activists has been much greater than I anticipated.”

David Abelson, executive director of the stewardship council, has advised local governments since 1999 on issues related to Rocky Flats, and he questions Lipsky’s understanding of the present-day conditions. “We probably had somewhere around 300 to 400 public meetings over those 10 or 11 years,” Abelson says of the cleanup. “Never once do I recall Jon Lipsky at any of those meetings. Never once.” Abelson also raises doubts about the raid, which he says “was based on premises that later turned out not to be accurate.” Abelson says the alleged nighttime incineration of plutonium never occurred.

That opinion is shared by Smith, Lipsky’s EPA partner on the Rocky Flats investigation. “Jon thought it happened, and I was 100 percent sure it didn’t happen,” Smith says, adding that the incinerator used by workers to burn protective suits and other waste using a box of matches “was literally the size of a backyard barbecue.” Although they disagreed over the incinerator question, both thought individuals had committed crimes at Rocky Flats. But Smith didn’t believe the investigation had produced sufficient evidence to indict anyone at a high enough level to have an impact. “Jon kind of went off the deep end,” Smith says. “He started seeing conspiracy theories in everything.”

Smith, who retired from the EPA in 2002, lives in Golden. He says he believes the refuge is safe. However, he adds, “Based on some of the things we saw out there, there were areas where they had stuff buried for years.” And when I asked him if he would buy a house in the Candelas development near Rocky Flats, his response was: “Not now, not ever. I think people are nuts buying downwind.”

The Candelas development, located south of the former plant, includes houses built up to the edge of Rocky Flats. Construction started several years ago, and the project will add 1,050 single-family homes over the next five years. The Candelas sales office put together a facts and information brochure that discusses the Rocky Flats cleanup and recent plans for trail construction. But parts of the glossy pamphlet are misleading. The brochure states that “the federal government constantly monitors the air, water, and soil quality” at Rocky Flats. The DOE does still monitor water, but the federal government stopped monitoring air and sampling soil in the mid-2000s. An image in the brochure shows pronghorns galloping in a meadow. Although there are dozens of animals in the refuge, pronghorns haven’t been spotted since before the plant was built. When I contacted Candelas to ask about the brochure, spokesperson Steven Silvers said, “If it’s inaccurate, it will be changed immediately.” At press time, a message on Candelas’ website said the brochure had been pulled from the site so the company could reverify its contents, and Silvers said the print version would be taken out of circulation.

This past January, Lipsky (while working in a Rocky Flats–related archive belonging to environmental nonprofit Eco-Ed) came across a state health department document from the late ’90s that maps out three dozen “potentially contaminated areas”—all located in what’s now the refuge. The report states that these areas are not “necessarily the result of unreported activities performed at Rocky Flats” but goes on to conclude: “All 36 areas need to be properly reviewed and the relevant concerns evaluated.” Spreng calls it “an old report already thoroughly considered and responded to.” He says officials during the cleanup inspected the areas and in some cases conducted additional sampling but determined they required no further action.

But Lipsky believes otherwise. Further digging suggested to him that for many of the areas identified in the study, there’s no evidence in public documents that crews followed up and addressed the potential problems. He discusses the report with lawyerlike detail in a 12-page letter he sent to the Colorado Solid and Hazardous Waste Commission in February. The letter serves as a synopsis of Lipsky’s present concerns, including the proposed controlled burns and public access to the refuge.

“The Rocky Flats Superfund site poses a potential imminent health risk to visitors at the Rocky Flats Refuge,” Lipsky wrote. “Absent competent soil and air sampling and analysis, the remedy, with a reasonable scientific certainty, is not protective of human health and the environment.” He continued, “The active Rocky Flats Superfund site and lack of any monitoring [of radioactive and other hazardous wastes] should be reasons enough to keep the refuge closed to the public.”

There are others who share Lipsky’s point of view. Kristen Iversen, who grew up in Arvada near the plant and is the author of a memoir and Rocky Flats history called Full Body Burden: Growing Up In The Nuclear Shadow Of Rocky Flats, says that since her book’s publication four years ago, additional current and former residents of the area around Rocky Flats have sent her stories of illnesses—primarily leukemia, lymphoma, brain tumors, and thyroid disorders. She is calling for community health surveys, epidemiological studies, and medical monitoring for people living near the former bomb–making facility. She says most of the suspect illnesses originate “within a 10-mile radius [of Rocky Flats] in particular, although it’s broader than that. Most of the stories are coming out of Arvada and Westminster.”

Michael Ketterer, who came to Denver in 2013 to chair the Metropolitan State University of Denver chemistry department, specializes in plutonium-isotope tracing. Ketterer has tested soil near Rocky Flats—including the Indiana Street corridor east of the refuge—and found elevated levels of plutonium compared with other locations he’s sampled in the continental United States. “There’s no other way to look at it,” Ketterer says. “Numbers don’t lie. There is a global background of plutonium, which everybody needs to take into account—but the baseline levels are far exceeded in the immediate vicinity of Rocky Flats. And we know with absolute certainty that it is from Rocky Flats.”

During the cleanup, government agencies set the radiation standard at which the environment would be assumed safe at 50 picocuries per gram. Once the cleanup was complete, the average level in the refuge was 1.1 picocuries per gram; however, Ketterer says, it’s possible a soil sample that tests below the safety standard could contain a “hot particle”—in this case, a nugget of concentrated plutonium. “Cleanup standards only address the bulk concentration of activity,” he says. “But plutonium is distributed differently through the soil.” And state health officials, he says, have chosen not to look into that issue.

The safe radiation standard for water at Rocky Flats was set at .15 picocuries per liter. Plutonium levels have not exceeded that standard as gauged at on-site stations that monitor compliance, according to Spreng—but the standard has been exceeded in the off-limits centralized area. “I think that we’re seeing the tip of the iceberg in the exceedances in the water,” Ketterer says, “and I think it’s natural as night follows day, we’re going to have more of that happen in the future.”

Federal and state officials insist Rocky Flats poses negligible risks to public health. Still, the former industrial section of the plant is closed effectively forever, since the contaminant plutonium-239, one of the isotopes handled there, has a half-life of 24,100 years. Lipsky says such danger at the property’s core is itself cause for skepticism. And activists point out other potential threats: A public highway authority is planning to complete a beltway around metro Denver by building the proposed Jefferson Parkway, construction for which could churn up plutonium-laced soil on the east side of the refuge. A landfill on a hillside just south of the former industrial section was left in place during the cleanup. No one knows exactly what’s in it, except it’s thought to contain at least some depleted uranium. The landfill started slumping two years after the cleanup was completed, and last year’s wet spring caused so much movement that instruments installed to monitor the landfill were damaged. Lipsky calls it “a landfill out of control.”

Activists and officials continue to debate points of immediate impact, but they generally agree on the need for perpetual vigilance at Rocky Flats. Part of the property is an eternal booby trap. “The long-term protection of Rocky Flats is directly dependent upon long-term engagement,” says Abelson, head of the stewardship council. “You don’t just say, ‘Oh, it’s done, let’s move on.’ It requires ongoing management, it requires ongoing oversight, it requires ongoing communication, and for me, the worrisome years are not the ones we’re in now. It’s what happens 50 years from now. It’s what happens 100 years from now.”

Last July, U.S. Fish and Wildlife managers began leading monthly guided public tours at the refuge. Interest was high and spots filled quickly. So far, about 100 members of the public and some media have been given a chance to enter the property. I was one of those people. Before I drove out to the refuge, I called Lipsky and asked for advice. “Wear booties,” he said.

I didn’t wear plastic booties, but I did wear an old pair of shoes. Refuge manager Lucas and U.S. Fish and Wildlife visitor services manager Cindy Souders led the tour. They pointed out expanses of rare plants at the refuge. They noted the refuge is home to more than 250 species of animals, including a herd of elk that rambled across a ridge. We visited the rustic structures of an old family ranch on the north side of the refuge and learned that the house was built in 1949, two years before the federal government took over. Someday soon, the guides said, people would be hiking, cycling, and riding horses where we were standing.When I got home, I took my shoes off in the garage. I couldn’t decide whether they were safe to bring into the house. After a week, I threw them out.

This piece was written by Quentin Young, who is the features editor at the Boulder Daily Camera. The story was edited by Chris Outcalt, fact-checked by Mary Clare Fischer, and copy edited by Jessica LaRusso. Unless noted otherwise, all photography is by Benjamin Rasmussen.