Acid Canyon is a tributary of Pueblo Canyon located in the Pajarito Plateau Region of Los Alamos County twenty-five miles northwest of Santa Fe. Currently, the area is a popular hiking destination, but in the early years of the United States nuclear program it served as a storage site for radioactive waste. The canyon earned its’ name because the industrial line used to transport waste is called an “acid” line and its position made it a convenient discharge site for the Los Alamos National Laboratory (LANL).

Beginning in 1943, untreated chemical waste containing isotopes, such as cesium, uranium, plutonium, americium and strontium, were dumped into the canyon. Eventually, a treatment plant was built to remove radioactive material from the waste, but it only focused on the main technical area (TA-45). In 1963, a Central Waste Treatment Plant was constructed to receive all the liquid waste from the region, which effectively ended the release of effluents into the canyon by the next year.

In the following years, the Atomic Energy Commission worked to decommission and decontaminate the Acid Canyon treatment plant. The facilities were demolished and 390 cubic yards of contaminated soil and rock were removed from the canyon so it could be safely transferred back to Los Alamos County. Currently, Acid Canyon is not only under long-term surveillance by the Office of Legacy Management, but it is also in compliance with the Department of Energy standards for radiological conditions and has been cleared for unrestricted use.