US Radioactive Waste Drums Remain Scattered Across San Francisco Seafloor
Between 1946 and 1970, the United States dumped approximately 47,800 containers of radioactive waste into the Pacific Ocean west of San Francisco. These steel drums, weighted with concrete, were not designed for long-term containment but merely to survive the descent to the seafloor. Due to poor navigation and lack of detailed record-keeping, many containers missed their designated sites, scattering across 1,400 square kilometers of seabed, much of which now lies within the Greater Farallones National Marine Sanctuary. While a 1981 review suggested the radioactivity had decayed to negligible levels, later studies found isotope signatures in local fish that differed from weapons fallout. Despite the ban on ocean dumping in 1994, no agency has proposed retrieving the drums, as the cost outweighs the measured hazard.
Key points
- Approximately 47,800 containers of low-level radioactive waste were dumped by the US between 1946 and 1970, 25 to 60 miles west of San Francisco.
- The containers included 55-gallon steel drums, concrete blocks, and other packaging, carrying an estimated 540 terabecquerels of thorium, uranium, and fission products.
- Poor navigation and lack of detailed records led to drums being scattered across 1,400 square kilometers of seafloor, rather than concentrated at three designated sites.
- A 1981 General Accounting Office review concluded that 90% of the radioactivity had decayed, but a 1996 study found isotope ratios in fish that did not match weapons fallout.
- The practice was banned globally in 1994, but no retrieval efforts have been proposed due to high costs and low measured risk.
- The dump site is now located within the Greater Farallones National Marine Sanctuary, which was designated in 1981, eleven years after the last dump.
Background
This story is part of a broader global issue of mid-20th-century ocean dumping of radioactive waste. Recent surveys in the Northeast Atlantic have confirmed that over 200,000 barrels dumped in the 1960s and 1970s are leaking radionuclides like cobalt-60 and cesium-137 into the seafloor. These findings highlight the long-term environmental impact of historical disposal practices, even in regions where the waste was not intended for permanent containment. The San Francisco dump site, while distinct in its location and specific waste composition, shares the same legacy of inadequate record-keeping and the assumption that ocean currents would dilute the waste.
Why it matters
The presence of radioactive waste drums within a national marine sanctuary underscores the long-term consequences of historical environmental decisions. While the immediate health risks to humans are considered minimal, the ecological impact on deep-sea ecosystems remains a subject of ongoing research. The lack of retrieval efforts highlights a policy gap where the cost of remediation outweighs the perceived hazard, leaving the waste to remain in place indefinitely. This case serves as a reminder of the importance of accurate record-keeping and long-term environmental monitoring in managing hazardous materials.
What to watch
No immediate action is planned to retrieve the drums, as no treaty obliges agencies to do so and the cost is deemed unjustifiable. The current policy is to monitor the site and leave the drums in place. Future research may focus on the long-term ecological impact of the waste on deep-sea organisms and the movement of radionuclides through sediment and water.
Want the full story? Read the original reporting
Read on Space Daily