Top 5 Most Radioactive Sites in the U.S.
- Craig Kaiser
- Jan 5
- 7 min read
The United States has a complex nuclear legacy spanning military weapons production, energy generation, and scientific research. While these programs powered the nation through the 20th century, they also left behind some of the most contaminated places on Earth. Understanding where these sites are located isn't just a matter of historical curiosity- it's essential information for property buyers, investors, and anyone concerned about environmental health. This resource explores the most toxic sites in the U.S. and how you can see if you're located near one.
Top 5 Most Radioactive Sites in the U.S.
The top 5 most radioactive sites in the U.S. are the Hanford Site, the Savannah River Site, the Nevada National Security Site, the Oak Ridge Reservation, and the Idaho National Laboratory. Below, we'll explore their histories, why they're so contaminated, and the ongoing efforts to clean them up.
1. Hanford Site, Washington
Located along the Columbia River in south-central Washington, the Hanford Site is considered the most toxic, radioactive site in the U.S. Established in 1943, this 586-square-mile site produced plutonium for nearly 5 decades for America's nuclear weapons program, including the "Fat Man" bomb dropped on Nagasaki. Hanford is a complex environmental nightmare. It contains approximately 56 million gallons of radioactive waste stored in 177 underground tanks, many of which are leaking. The primary concern is the potential for this waste to reach the Columbia River, a vital waterway for the Pacific Northwest.
Cleanup efforts have been ongoing for decades, and costs are estimated to exceed $100 billion, making it one of the most expensive environmental remediation projects in world history. Workers are currently vitrifying the waste- turning it into glass logs for safer long-term storage- but technical challenges and high costs make this a slow, difficult process. The Department of Energy projects cleanup won't be complete until at least 2060.
2. Savannah River Site, South Carolina
The second most radioactive site in the U.S. is the Savannah River Site in South Carolina. Spanning 310 square miles near Aiken, South Carolina, the Savannah River Site produced plutonium and tritium for nuclear weapons from the 1950's through the end of the Cold War. The facility processed nuclear materials for more than 6,000 weapons and generated massive quantities of radioactive waste in the process. Today, the Savannah River Site houses approximately 37 million gallons of high-level radioactive waste in underground storage tanks.
There is significant groundwater and soil contamination from years of industrial activity. Groundwater contamination is the most significant concern, with radioactive materials having migrated through the soil toward nearby waterways. Cleanup efforts continue, with some areas expected to require monitoring and management for centuries. The SRS has made significant progress in stabilizing waste compared to other sites. They use a process similar to Hanford, converting liquid waste into a solid glass form. However, the site still manages huge quantities of nuclear materials, and complete remediation is a long-term goal that will take decades to achieve.
3. Nevada National Security Site
The third most radioactive place in the U.S. is the Nevada National Security site, spanning 1,360 square miles. Approximately 65 miles northwest of Las Vegas, the Nevada National Security Site was the primary location for U.S. nuclear weapons testing from 1951 to 1992. More than 900 nuclear tests were conducted here, including 100 atmospheric tests before the 1963 Limited Test Ban Treaty. The Nevada National Security Site is permanently contaminated with radioactive materials from decades of nuclear explosions. While no longer used for full-scale nuclear testing, the site remains active for weapons experiments using smaller amounts of nuclear material. Large areas of the site will remain closed to the public indefinitely due to lingering radiation.
Cleanup is led by the Department of Energy’s Environmental Management Nevada Program under strict federal agreements, focusing on soil remediation, groundwater monitoring, demolition of old test structures, and safe management of radioactive waste. Over 130 contaminated soil sites have already been addressed, while long-term monitoring continues for groundwater and remaining facilities. The program also manages low-level radioactive waste disposal and plans for phased transition to long-term stewardship, ensuring public safety and environmental protection decades into the future.
4. Oak Ridge Reservation, Tennessee
The Oak Ridge Reservation in Tennessee is another highly toxic, radioactive site in the United States. Oak Ridge was the administrative and military headquarters for the Manhattan Project. This "Secret City" was built to enrich uranium and became heavily contaminated over decades of nuclear weapons production and research. At its peak, the facilities at Oak Ridge consumed one-seventh of all the electricity produced in the United States. The legacy of Oak Ridge includes contaminated buildings, burial grounds for solid waste, and polluted surface water. Mercury contamination is a specific and severe issue here, particularly in the East Fork Poplar Creek, resulting from lithium isotope separation processes used during the Cold War.
Approximately 15% of the 33,000-acre site is contaminated, leading to its designation as a Superfund site in 1989 and initiating one of the nation’s largest environmental cleanup efforts. Significant demolition has been undertaken to remove contaminated structures. The cleanup is managed by the Department of Energy’s Oak Ridge Office of Environmental Management (OREM) in collaboration with the EPA and the Tennessee Department of Environment and Conservation (TDEC) under a Federal Facility/Superfund agreement, which sets cleanup standards and oversight. Similar to Hanford and Savannah River, this is a multi-decade project.
5. Idaho National Laboratory
Sitting on 890 square miles of high desert, the Idaho National Laboratory (INL) has been the center of nuclear energy research since 1949. It is the place where nuclear energy was first generated for usable electricity, and stands as one of the most toxic sites in the country because it is home to spent nuclear fuel, transuranic waste, and legacy waste from decades of reactor operations. The Idaho National Laboratory sits directly above the Snake River Plain Aquifer, which is a critical water source for Idaho’s agriculture and residents. The site's Subsurface Disposal Area contains approximately 11 million cubic feet of buried radioactive and hazardous waste. Historically, waste was sometimes injected directly into the aquifer or buried in shallow pits. This led to a plume of contamination that threatened the regional water supply.
A massive effort has been underway to remove buried waste and treat the groundwater. The "pump and treat" method is used to clean the aquifer, and older waste barrels are being exhumed and shipped to WIPP in New Mexico. There are also ongoing waste retrieval, treatment, and vitrification projects (turning liquid radioactive waste into glass logs). Monitoring shows that contamination levels in the aquifer are dropping, marking a success for environmental remediation efforts. However, some areas are still highly radioactive and restricted.
Honorable Mentions: More Toxic Sites in the U.S.
The Hanford Site, the Savannah River Site, the Nevada National Security Site, the Oak Ridge Reservation, and the Idaho National Laboratory stand as the top 5 most toxic sites in the U.S. While rankings may vary, these sites are consistently prioritized due to their history of intensive nuclear activity and massive volumes of radioactive waste. Additional radioactive sites in the U.S. include the Rocky Flats Plant in Colorado, the Los Alamos National Laboratory in New Mexico, the West Valley Demonstration Project in New York, and the Moab Uranium Mill Tailings in Utah.
Rocky Flats Plant, Colorado: This site formerly produced nuclear weapons components, specifically plutonium pits used as fissionable cores for nuclear explosions. Significant contamination occurred following two major plutonium fires in 1957 and 1969, which released radioactive material into the surrounding soil. After an extensive cleanup, the area is now a Superfund site subject to ongoing long-term monitoring.
Los Alamos National Laboratory, New Mexico: Home to the atomic bomb's creation and ongoing nuclear research, Los Alamos National Laboratory is located near Santa Fe, New Mexico. Decades of nuclear activities have contaminated nearby soils, canyons, and water systems with radioactive materials like plutonium, americium, and strontium-90. Concerns grew after the 2000 Cerro Grande Fire and 2011 Las Conchas Fire, which risked spreading radioactive particles through smoke and ash.
West Valley Demonstration Project, New York: Located about 35 miles south of Buffalo, the West Valley Demonstration Project was the only commercial nuclear fuel reprocessing facility to operate in the U.S. From 1966 to 1972, it processed 640 metric tons of spent nuclear fuel, generating over 600,000 gallons of highly radioactive liquid waste stored in underground storage tanks. The site also contains low-level radioactive waste and contaminated equipment. The West Valley Demonstration Project Act of 1980 mandated its cleanup, which has become one of the most complex and lengthy radioactive remediation projects in the country.
Moab Uranium Mill Tailings, Utah: Located along the Colorado River, this site contains about 16 million tons of uranium mill tailings- the radioactive, sand-like waste left after processing uranium ore. The mill operated from 1956 to 1984, producing uranium for nuclear fuel and weapons. After its closure, the tailings remained in a large, unlined pile, contaminating nearby soil, groundwater, and the river. Cleanup, managed by the U.S. Department of Energy (DOE) in coordination with the EPA and Utah, began in 2009.
Is it Dangerous to Live Near a Superfund Site?
Living near Superfund sites doesn't necessarily mean you are in immediate danger, but ignorance is not bliss. Environmental factors affect property values, long-term health, and peace of mind. Knowing what is in the soil and groundwater near a potential home or investment property is crucial due diligence. According to the National Library of Medicine, studies show that living near a Superfund site can be linked to serious health risks, from adverse birth outcomes to chronic diseases. Contaminants from these locations can easily migrate into the air, soil, and dust of neighboring homes. In a radiological emergency, the release of radioactive substances or gases can expose people to radiation externally or internally if absorbed into the body. High doses of radiation can lead to acute effects such as burns or hair loss.
Understanding Environmental Risks Near You
Whether you are a real estate investor, an outdoor enthusiast, or just a concerned citizen, seeing the full picture and finding out if a property is contaminated helps you make smarter decisions. One tool you can use to find hazardous sites is the EPA's Superfund program. This tool shows contaminated sites nationwide, many containing radioactive materials or other dangerous contaminants that can affect property values, development potential, and human health.
You don't need a Geiger counter to find out what's in your backyard. You just need the right data. Another tool you can use to see contaminated sites across the country and evaluate contamination risks is LandApp. LandApp makes it easy to visualize environmental hazards right on the map. With our free app on the Apple and Google Play stores, you can see the locations of Superfund sites nationwide.
For more detailed analytics about a specific property's contamination potential, you can generate 3 free PDF Property Reports that rate it's Industrial Contamination risk on a scale of 0 to 100 within our proprietary risk index scores. Create a free LandApp account, then find a parcel on our map to generate your free Property Report: