Handwritten warning on 2002 oil-well permit raises questions amid Ladera Ranch cancer cluster

Officials discovered handwritten annotations on a 2002 permit for the abandonment of a historic oil well beneath the Ladera Ranch community in Orange County, California. The notes, reportedly written by engineer Floyd Leeson, read, “This well is not to be built over without further considerations,” and were marked to be included on the final letter.

State oil-and-gas supervisors William F. Guerard Jr., Kenneth Henderson and deputy R.K. Baker signed the permit when the well was sealed on Feb. 26, 2002. Henderson later told the Los Angeles Times he did not recall the reason for the comments but suggested the well-plugging might not have met current standards. The Department of Conservation described the markings as possibly a clerical error but did not explain the specific instruction to add them to the final letter.

The discovery coincides with a cluster of at least six Ewing sarcoma cases diagnosed in Ladera Ranch between 2013 and 2024, a rare cancer that primarily affects children and young adults. Residents have raised concerns about potential environmental contributors, including pesticides used on school grounds and a nearby landfill site, while health officials continue to investigate.

Karen Lincoln, director of the Center for Environmental Health Disparities Research at UC Irvine, said the notes merit further examination. “If an engineer specifically raised a concern about building over a well, it’s reasonable to ask what that concern was and whether it was resolved before homes were built,” she said. Lincoln noted that improperly sealed wells can allow gases or volatile organic compounds such as methane, benzene or other hydrocarbons to migrate toward the surface, but emphasized the need to establish whether any substances are actually being released and reaching occupants at harmful levels.

The California Geologic Energy Management Division advises against constructing buildings over sealed wells to maintain access and reduce leakage risk, though it acknowledges that sealed wells are not guaranteed to be leak-free. The Environmental Protection Agency said it is cooperating with local and state agencies and stands ready to provide technical assistance.

Community members, including parents of children diagnosed with Ewing sarcoma, have called for transparent investigation results. The newly surfaced notes add another layer to the ongoing inquiry into possible environmental factors linked to the cancer cluster.