Well, CSO 4 (Pico 4)

Charles Mentry drilled this one with tools he improvised, including a drill stem welded together from railroad car axles bought off the Southern Pacific. Oil came in on September 26, 1876 at 370 feet, twenty-five barrels a day; deepened the following year, it threw a fountain over the top of a sixty-five-foot derrick. It was California's first commercially productive well and it kept producing until 1990, which makes it the longest-running oil well on record.

What the plaque says

On this site stands CSO-4 (Pico #4), California's first commerically productive well. It was spudded in early 1876, under the direction of Demetrius G. Scofield, later to become first president of Standard Oil Company of California, and was completed at a depth of 300 feet on September 26, 1876, for an initial flow of 30 barrels of oil a day. Later in the same year, the well was deepened to 600 feet, using what was perhaps the first steam rig employed in oil well drilling in California. Upon this second completion, it produced at a rate of 150 barrels a day, and is still producing after seventy-seven years. The success of this well prompted formation of the Pacific Coast Oil Company, a predecessor of Standard Oil Company of California, and led to the construction of the state's first refinery nearby. It was not only the discovery well of the Newhall Field, but was, indeed, a powerful stimulus to the subsequent development of the California Petroleum Industry. State Registered Landmark No. 516.

Where it stands

More markers nearby

• Mentryville — 1.2 mi
• Rancho San Francisco — 5.0 mi
• Pioneer Oil Refinery — 6.2 mi
• Lyons Station Stagecoach Stop — 7.0 mi