Handwritten warning on abandoned well fuels Ladera Ranch cancer mystery

A pair of pencil annotations on a Department of Conservation permit, likely written by engineer Floyd Leeson, advise that the historic oil well beneath present-day Ladera Ranch should not be built over without additional consideration. The permit, signed by William F Guerard Jr, Kenneth Henderson and R.K. Baker when the well was sealed in February 2002, contains the warning twice, with a marginal note to "Put on final letter."

Since 2013, the affluent Orange County community has seen six diagnoses of the ultra-rare Ewing sarcoma, sparking theories linking the cases to school pesticides, a local landfill, or the abandoned well. UC Irvine’s Karen Lincoln cautions that while the note signals a potential issue, it does not confirm any hazardous exposure, and calls for testing of gases or contaminants that might migrate from the well. CalGEM advises against construction over sealed wells but admits no guarantee against leaks. Parents such as Bonnie Regan and Dustin Matteson, who lost a child to the disease, are pressing officials and developers like DMB Developments for a clear, evidence-based response.