Last October, California passed the nation’s strongest law to address the glut of oil and gas wells that are unplugged and ownerless, many leaking pollutants into the environment.

The legislation required that, as part of any sale or transfer of wells, the purchasing company set aside enough money in financial instruments known as bonds to cover the entire cleanup cost of low-producing wells if the companies go out of business without plugging them. It was a striking departure from the piecemeal steps taken by other state legislatures and federal agencies to reduce the number of orphan wells. California lawmakers repeatedly cited ProPublica’s work on the subject as a reason to act.

But in its first major test, California regulators sidestepped the law.