Elk Hunting at Rocky Flats: DOE Documents Wildlife Crossings, but Where Are the Radionuclide Test Results?

Tiffany Hansen

Oct 17

9 min read

Updated: Oct 21

Federal records show that elk cross into the restricted Central Operable Unit and that wildlife crossings were deliberately installed. Refuge manager David Lucas says elk were tested for radionuclides in 2023. As hunting begins, Rocky Flats Downwinders wants to see the actual laboratory results.

Elk hunting raises an important public-health question

For the first time, elk hunting is underway at Rocky Flats National Wildlife Refuge, the former buffer zone surrounding the Rocky Flats nuclear weapons plant northwest of Denver. The U.S. Fish and Wildlife Service (USFWS) began a pilot elk hunt in September 2026 to help manage a growing herd. Hunting is scheduled to continue through December 14.

But Rocky Flats is not an ordinary wildlife refuge. The former nuclear weapons facility manufactured plutonium components for decades. Historical operations released radioactive and hazardous materials into the environment. Although an accelerated cleanup was completed in 2005, a central portion of the former site remains under Department of Energy (DOE) management, with restrictions on public access and land use. Now, hunters may harvest elk from the surrounding refuge and take the meat home for consumption.

If elk can move through land that remains closed to the public because of its environmental history, what evidence establishes whether those animals are safe to eat? DOE's own records show that elk have crossed the restricted area's perimeter fence for years—and that the government deliberately installed wildlife-friendly crossings to facilitate their movement.

Those records make access to the reported 2023 elk radionuclide-testing results particularly important.

DOE documented elk crossing into the Central Operable Unit

The Central Operable Unit (COU) encompasses the former industrial portion of Rocky Flats that remains under DOE management. Unlike the surrounding wildlife refuge, this area is not open to general public access. However, the perimeter fence has not prevented elk from moving across the boundary. In its 2018 Ecological Monitoring Annual Report, DOE documented dozens of locations where elk crossed the COU fence. The report described fence wires that had been broken or pulled from posts as elk jumped over them.

DOE also acknowledged that the animals had become common throughout the site, with an estimated population exceeding 200 elk at that time. The agency was considering wildlife-friendly crossing options to reduce fence damage and the possibility of injury to animals.

These observations establish that elk movement across the COU boundary was known to federal officials.

Read DOE's 2018 Ecological Monitoring Annual Report — Section 6.2.4

DOE installed wildlife crossings in 2019

The story did not end with broken fences. DOE's Second Quarter 2019 Site Surveillance and Maintenance Report confirms that wildlife-friendly crossings were installed at several locations along the Central Operable Unit fence. The agency explained that these changes would allow wildlife to cross while reducing the risk of injury and damage to the fencing.

In other words, federal officials were not merely observing wildlife movement across the COU boundary. They were deliberately accommodating it. The reason for those crossings—wildlife protection and better fence management—is understandable. But the crossings also raise questions about environmental exposure. The Central Operable Unit is subject to restrictions because residual contamination and other environmental conditions require ongoing management. Animals do not necessarily remain within those boundaries. They can move between the COU, the surrounding refuge, and nearby properties.

Read DOE's Second Quarter 2019 Surveillance Report — Section 5.0, Ecological Monitoring

DOE continued documenting elk movement

Additional DOE records show that wildlife crossings remained part of the site's ecological management program. A 2023 DOE quarterly presentation reported the addition of a wildlife crossing and included a photograph captioned Elk using wildlife crossing. A 2024 DOE report described additional crossings intended to facilitate wildlife movement. Together, these records establish that wildlife movement across the COU fence was an ongoing management consideration—not an isolated observation. They do not tell us precisely where every elk traveled or whether individual animals consumed contaminated vegetation or soil.

But they establish that the boundary restricting human access does not isolate wildlife from the same area.

Read DOE's 2023 First-Quarter Report Summary — Slide 18

Read DOE's 2024 First-Quarter Surveillance Report

David Lucas says elk were tested in 2023

On October 16, 2026, KUNC public radio journalist Rachel Cohen published a report examining the new Rocky Flats elk hunt and continuing concerns about the site's environmental history. The article included a particularly important statement from David Lucas, manager of Rocky Flats National Wildlife Refuge. Speaking to a Boulder County board in 2025, Lucas said elk collected in 2023 had been sampled for radionuclides. He reported that the results were nondetect in all tissues examined. That is a significant statement.

If the testing was conducted as described, laboratory records should document which animals were tested, where they were collected, which tissues were sampled, which radionuclides were analyzed, and the analytical methods used.

Rocky Flats Downwinders has not obtained the underlying 2023 radionuclide-testing records.

Without those records, the public cannot independently evaluate the scope or sensitivity of the testing Lucas described. We are not claiming that the testing never occurred. We are asking to see the evidence supporting the public statement.

Read Rachel Cohen's October 16, 2026, public radio report

In 2025, David Lucas also published research on PFAS in elk

There is another important development in this story. In December 2025, a peer-reviewed study titled Assessing PFAS Exposure in Rocky Mountain Elk Populations Adjacent to the Former Rocky Flats Nuclear Site: A Preliminary Analysis was published in PLOS ONE.

David Lucas was an author of the research, along with collaborators from federal and state agencies, including the Colorado Department of Public Health and Environment. The study examined PFAS exposure in elk associated with the Rocky Flats area. PFAS are persistent chemical contaminants sometimes called forever chemicals. They are not the same as radionuclides such as plutonium-239/240 or americium-241.nTesting for PFAS does not establish whether an animal contains radioactive contaminants. That distinction is important.

The 2025 PFAS publication is publicly available, with authors, methods, results, and supporting scientific information that readers can examine. The separate 2023 radionuclide testing described by Lucas has not been made available to the public in comparable form. We want to understand why. Were the radionuclide results produced as part of the same broader wildlife sampling effort? Were they conducted under a separate project? Which laboratory performed the work, and which agency maintains the records? The existence of the published PFAS study demonstrates that elk research involving Lucas and multiple government agencies has been conducted and documented. It does not establish what radionuclide testing was performed.

Read David Lucas and colleagues' 2025 PFAS study in PLOS ONE

What does nondetect mean?

A laboratory finding of nondetect does not necessarily mean that a substance is completely absent. It generally means that the substance was not detected above the threshold established by the analytical method. That threshold matters. For radionuclide testing, interpreting a nondetect result requires information about the laboratory's detection limits, analytical uncertainty, sample preparation, and quality-control procedures. It also matters which tissues were examined. Testing muscle tissue alone, for example, would not provide the same information as testing muscle, bone, liver, kidney, and other tissues. The number of animals and their locations also matter. A limited sample can provide useful information, but it cannot automatically establish the exposure history or tissue concentrations of every elk moving through Rocky Flats.

Without the laboratory records, the public cannot determine what the reported nondetect results establish—or what they leave unanswered.

Why the Central Operable Unit matters to hunters

The DOE crossing records introduce another consideration. The surrounding refuge is open for designated recreational activities, including the new elk hunt. The Central Operable Unit remains restricted. Yet elk are capable of moving between the two areas. Animals may encounter soil, vegetation, dust, and water during their movements. Whether those pathways result in meaningful radionuclide uptake depends on environmental concentrations, animal behavior, exposure duration, and the biological properties of the contaminants. The crossing records do not prove that elk have accumulated radionuclides. Nor do they establish that elk harvested at the refuge are unsafe to consume. However, the possibility of movement into and out of a restricted former industrial area raises reasonable questions about the adequacy of wildlife sampling. Were any elk collected for the reported 2023 tests known to have entered the COU? Were their movements tracked? Did sampling account for animals using different parts of the site? Were the tissues most relevant to human consumption examined?

And were the results evaluated specifically for hunters and their families? These are questions that the original testing records may help answer.

Earlier deer research demonstrates why the details matter

In 2005, researchers Andrew S. Todd and R. Mark Sattelberg published Actinides in Deer Tissues at the Rocky Flats Environmental Technology Site. The peer-reviewed study examined tissues from deer associated with Rocky Flats and analyzed them for radionuclides, including plutonium, americium, and uranium.

Some analyses detected radioactive materials above laboratory detection limits.

The researchers nevertheless estimated that consumption of the tested deer tissues presented minimal human health risk under the assumptions used in their assessment.

The study is useful because its methods and findings can be evaluated. It also demonstrates that detecting a radionuclide and establishing a harmful exposure are different scientific questions. But deer are not elk. Different animals may have different movement patterns, feeding behavior, and exposure histories. The 2005 deer study cannot substitute for the reported 2023 elk testing.

Read the 2005 peer-reviewed deer tissue study

Rocky Flats Downwinders is seeking the missing records

RFD is pursuing the original 2023 radionuclide-testing documentation through the Freedom of Information Act. We want to obtain the records described by David Lucas and understand what they show. Among the information we are seeking are:

The number of elk collected and the locations where they were sampled.
Which tissues were submitted for laboratory analysis.
Which radionuclides were tested, including plutonium, americium, and uranium isotopes.
Laboratory results, detection limits, uncertainties, and quality-control records.
Information about whether the tested animals had occupied or crossed into the Central Operable Unit.
Any written assessment of potential health risks associated with consuming elk meat.
Records identifying which agencies conducted, commissioned, reviewed, or received the testing.

We are also interested in the location and design of the wildlife crossings documented by DOE, along with any monitoring records showing how elk use the COU and surrounding refuge. These are requests for existing scientific and government records. They are not accusations that any agency has deliberately concealed testing. But when federal officials publicly cite scientific results relevant to hunters and their families, we believe those results should be available for independent examination.

The public deserves the evidence

The U.S. Fish and Wildlife Service has important responsibilities for wildlife conservation, habitat management, and public recreation. DOE has continuing responsibilities for the restricted Central Operable Unit and the long-term management of the former industrial site.

These agencies have different roles, but wildlife moves across their management boundaries.

The public deserves to understand how that movement is considered when decisions are made about hunting, environmental monitoring, and potential human exposure. There may be reassuring findings in the reported 2023 radionuclide tests. If so, releasing the data would provide an opportunity to demonstrate that. There may also be limitations in the sampling or questions that require further examination. Those should be communicated as well.

This is the purpose of Rocky Flats Downwinders' Truth & Transparency project: to seek the original evidence, understand what it establishes, and identify what remains unanswered.

The question is not whether elk definitely are—or are not—contaminated. The question is whether government agencies can provide the scientific documentation necessary for the public to evaluate their statements.

A straightforward request

DOE documents elk moving across the Central Operable Unit boundary. DOE documents the installation of wildlife crossings. David Lucas publicly reported that elk collected in 2023 were tested for radionuclides and that all tested tissues produced nondetect results. Lucas also participated in a peer-reviewed PFAS study involving Rocky Flats-area elk that was published in 2025. And now elk hunting is underway at the refuge. The missing piece is the underlying 2023 radionuclide-testing record. For hunters who may bring elk meat home to their families, for surrounding communities, and for everyone concerned about the environmental legacy of Rocky Flats, that information matters. If the testing was done, make the results available. That is what Rocky Flats Downwinders is asking.