Oil Well Production Record: CSO-4 (Pico No. 4), 1876-1990
Pico Canyon, California

Source: California Department of Conservation / Division of Oil, Gas & Geothermal Resources (DOGGR)

Documents detail Chevron USA's successful negotiations with the National Park Service in 1989-1990 to maintain CSO-4's National Historic Landmark status after the well was abandoned — and the unusual method used to cap the well, as agreed to by NPS, so as not to lose the status.

Last page shows transcript of Charles A. Mentry's notes (1876-1896) pertaining to findings at different depths.