10 MONTEREY COUNTY WEEKLY FEBRUARY 19-25, 2026 www.montereycountynow.com California’s oil industry is over 150 years old, with its commercial beginnings traced back to the fittingly named Petrolia in Humboldt County. Production peaked in the 1980s before entering a steady decline, with wells falling out of production and creating a scattered and increasingly difficult problem to manage throughout the state. Today, there are more than 30,000 idle oil and gas wells, defined as wells that have been inactive for at least 24 months. Although these wells are no longer commercially productive, they can still leak oil and emit pollutants, including carcinogens like benzene and formaldehyde, air emissions including methane and pose physical hazards. In California, at least 4,449 of these wells are within 3,200 feet of a school, hospital, playground or elder care center, according to an analysis conducted by the nonprofit Center for Biological Diversity. The threats posed by idle wells in Monterey County, however, raise different concerns: The risk is less about neighboring hospitals or other actively used sites and more about drinking water reserves. Monterey County has at least 474 idle wells, according to the analysis, 97 percent of which are located above groundwater sources, including many that supply drinking water to residents and irrigation water to farmers. “A major determinant of an idle well’s risk level, in terms of being a pollution pathway, is its age, or how long it’s been sitting unplugged,” says Emily Diaz-Lore, staff scientist with the Center for Biological Diversity. “Age matters because the internal well infrastructure that is supposed to mitigate the migration of gases can deteriorate over time. If there’s not frequent monitoring of the well integrity, we don’t know how much of a risk the well poses to the surrounding groundwater sources, soil or air.” In Monterey County, at least 35 percent of the idle wells have been unplugged for more than eight years, and around 10 percent have remained unplugged for more than 20 years. Statewide, at least 168 idle wells have been unplugged for more than 10 years. Oversight of these wells, how they are maintained and who is responsible for paying for cleanup, can be tricky. Many operators, whether businesses or individuals responsible for the wells, go bankrupt, dissolve, die or become difficult to locate. The California Department of Conservation’s Geologic Energy Management Division (CalGEM) is responsible for regulating and overseeing idle, deserted and orphaned wells, coordinating with operators and contractors depending on whether a liable party has been identified. The differences in the classification—idle, deserted or orphaned— depend on whether or not a responsible party has been identified and can maintain the well. Idle wells have an identified operator who remains responsible for maintenance and eventual plugging; deserted wells are one step closer to becoming orphaned, meaning an owner may still be identified but compliance is uncertain. Orphan wells, or those with no solvent responsible party, are the outcome that the state seeks to prevent. In those cases, the state assumes responsibility for environmental cleanup and bears the financial cost of plugging a well. About 12 percent of Monterey County’s oil and gas wells are located within 200 feet of a river or creek. This includes the Salinas River, which runs through the San Ardo oil field, and is a critical source of the county’s groundwater. In December 2025, over 4,000 gallons of oil and toxic wastewater spilled in the San Ardo oil field, just over a mile from where the Sargent Creek feeds the Salinas River. It is unconfirmed whether that spill was connected to an active or idle well, although the location on the Governor’s Office of Emergency Services Hazardous Materials Spill report matches a few idle wells listed in CalGEM’s well tracker system. A notice of violation CalGEM sent to Aera LLC, the operator connected to the spill, on Dec. 19 shows the spill came from a pipeline, although it’s unclear which well (or wells) that pipeline is connected to. “When we went and checked it out we were concerned, and found out it was much to do about nothing,” says Mary Orradre, wife of Mike Orradre, whose family leases out rights to oil operators in San Ardo. She’s unsure whether or not the spill that occurred is associated with an idle well. “There have been regulations with the oil industry, some are necessary, but nobody gives us credit for all the compliance that we do. Are environmentalists and regulators being realistic? That’s a question that has to be asked and it isn’t.” San Ardo is a hotspot in the county, with a cluster of both active and idle wells, according to CalGEM data. Maps also depict clusters of idle wells just south of Greenfield near Monroe Creek, and just north of the San Ardo field along Paris Valley Road. The San Ardo oil field is operated by Chevron and Aera Energy LLC, which merged into California Resources Corporation in 2024. (The company did not respond before the Weekly’s deadline.) The cost to plug an individual well isn’t cheap, with recent costs ranging from $220,000 per well up to $900,000 per well, depending on the well’s location, condition and depth. A 2025 report published by Carbon Tracker estimates it could cost upward of $21.5 billion to plug the state’s wells. “One of the problems with wells being orphaned, is no one’s watching them,” says Cooper Kaas, staff attorney with the Climate Law Institute, “except for the communities that are directly affected by whatever is coming out of them …when there’s no responsible operator, then no one really knows what’s happening with the well until there’s a problem.” Spud Out Hundreds of unplugged oil wells sit on top of groundwater sources in Monterey County, a study finds. By Katie Rodriguez NEWS Above: The Center for Biological Diversity created an interactive map to show where idle wells are located throughout the state, depicting a cluster of idle wells just south of San Ardo (shown above). Below: The San Ardo oil field is the center of the industry’s operations in Monterey County. “We don’t know how much of a risk the well poses.” CENTER FOR BIOLOGICAL DIVERSITY NIC COURY
RkJQdWJsaXNoZXIy MjAzNjQ1NQ==