How can this be?  There are historical oil wells associated with the Yorba Linda Oil Field surrounding the Diemer Drinking Water Treatment Plant in Yorba Linda, CA,  it is part of the Brea-Olinda Oil Field operated by Aera Energy LLC.   Ladera Ranch CA drinking water source is Robert B. Diemer Water Treatment Plant 3972 Valley View Ave   Yorba Linda CA. It sits directly on top of 2 old Shell oil & gas wells that were plugged & capped in 1954 currently operated by Aera Energy LLC. One of the Shell oil & gas wells was drilled down to 4,199 feet and the other one was drilled down to 5,001 feet.  Robert B. Diemer Water Treatment Plant is formally designated as a critical facility.  Oil wells drilled before the 1970s often feature degraded steel casings and incomplete cement seals, creating direct vertical pathways for hydrocarbons, benzene, methane, or toxic formation brines to migrate up into foundations. Additionally, wells plugged prior to 1...