BAXTERVILLE –– There’s no signpost marking Mississippi’s only nuclear test site. There’s no visitor center, either — just timberland, wildlife … and a radioactive legacy buried beneath the surface.

While the federal government keeps watch over what lies underground, many younger residents don’t even know it’s there.

The Tatum Salt Dome, also known as the Salmon Test Site, spans 1,470 acres in Lamar County, about 21 miles southwest of Hattiesburg and 10 miles west of Purvis. It’s the only place east of the Mississippi River where the U.S. has detonated a nuclear device.

In the mid-1960s, federal officials used the salt dome to test underground nuclear explosions. Today, the land looks like any other Mississippi forest — but its history remains radioactive.

Why Mississippi — and what happened here

 In 1960, the U.S. Atomic Energy Commission’s Site Evaluation Committee selected the Tatum Salt Dome for underground nuclear testing. According to the Mississippi Department of Archives and History’s electronic publication Mississippi History Now, other potential sites across the state were evaluated before the dome was chosen for its dense salt deposit and geological stability.

The salt dome — almost circular and roughly 5,000 feet wide — lies about 1,500 feet below the surface. It is a remnant of an ancient sea that once covered the region during the Mesozoic era.

“The government had realized, and people realized, that if they blew up atomic weapons in the air or on the ground or underwater, then it really produced a great deal of pollution,” said Mark Puckett, a geology professor at the University of Southern Mississippi.

The site was first used under Project Vela, a U.S. Department of Defense program that aimed to improve the detection of underground nuclear explosions during the Cold War.

The program included a series of tests under Project Dribble and later Project Miracle Play.

— 1964 Salmon Event: A 5.3-kiloton nuclear explosion, equivalent to roughly one-third the force of the 1945 Hiroshima bomb.

— 1966 Sterling Event: A follow-up blast with a 0.38-kiloton yield.

— 1969 and 1970 gas explosions: These non-nuclear detonations were part of a study to simulate seismic signals for detection purposes.

Puckett recalled the unexpected power of the first detonation.

“Some buildings around here were damaged in the first event. The first explosion in (1964) turned out to be quite a bit larger than what they expected,” he said.

Before the 1964 test, nearby residents were paid $10 per adult and $5 per child to evacuate.

Carey Varnado, a Hattiesburg attorney who lived in the area during the tests, said many people didn’t realize the possible risks at the time.

“The government told people that any radiation or other potential damage like that would be very controlled and that there was essentially nothing to worry about,” he said. “(It) turns out there was a little more to be worried about perhaps than the government let us know at that time.”

Fallout and health effects

While the federal government compensated residents for property damage and contaminated wells, concerns about long-term health impacts lingered for decades. Locals reported higher rates of cancer and birth defects in animals near the blast site.

Stephen Cresswell, a historian and author of a Mississippi History Now article, wrote that residents voiced complaints about lasting health effects in the years following the tests. Around 2000, the government proposed building a water pipeline to provide clean drinking water from a location farther from the test area.

Varnado recalled hearing disturbing reports during the 1980s: “I remember shortly after I moved back here in 1980 there was a fair amount of publicity about animals near the test site that were being born with deformities and, more importantly, a high incidence of cancer among people who were near the test site.”

Although some monetary compensation was issued for immediate damage, Varnado said questions remain about whether health-related claims were ever fully addressed.

“I’m not sure that enough people down there have been compensated perhaps for their illnesses and even deaths,” he said. “There was some compensation paid. I know they paid a good bit for damages to buildings within a few miles of the test site. But I’m not really sure whether there’s ever been anything paid for illnesses and deaths to the people down there, and I would like to see it investigated more. I really would.”

According to Mississippi History Now, the government initially downplayed the potential risks to human health. Varnado said few residents were alarmed before the first test and accepted the government’s assurances at face value. Over time, however, public awareness grew — particularly among those who lived closest to the site.

Cleanup, oversight and the forest today

After the 1964 nuclear test, radioactive material was unintentionally brought to the surface when scientists drilled into the underground cavity two months later. A similar incident occurred in 1966. The federal government launched a cleanup in 1972, demolishing contaminated buildings and transporting debris and equipment to the Nevada Test Site north of Las Vegas for disposal.

Contaminated soil and fluids were injected into the original test cavity. A stone monument was placed at the site to warn against any future drilling or excavation. The warning is meant to protect against disturbing radioactive material still buried deep underground.

Hydrologic monitoring began that same year. Since 1992, the U.S. Department of Energy has conducted detailed assessments to evaluate residual contamination. The Energy Department continues to enforce deed restrictions that prohibit any excavation, drilling or material removal — whether vertical or angled from outside the site — without prior approval.

The department’s Office of Legacy Management manages long-term monitoring and maintains all site records and agreements. Since 2019, Mississippi state officials have participated in biennial water sampling to track groundwater and surface contamination.

While Mississippi owns the surface land, the federal government retains mineral rights and authority over hazardous materials under the Atomic Energy Act.

From 1972-1992, the land was leased as a private timber plantation. In 2010, the Mississippi Forestry Commission took ownership of the surface and now manages it as a demonstration forest and wildlife sanctuary. The area is not marked for visitors, and most people driving by would not know its history.

“My perception is that younger people really don’t know about it much at all,” Varnado said. “Those of us who were here at the time do have a memory that it occurred and have kept up with it somewhat.”

Despite the forest’s peaceful appearance, the site remains under strict federal oversight — a quiet reminder of a Cold War legacy buried beneath Mississippi soil.