Pipeline operators need to ensure safety is centered around either active or abandoned status as idled is not recognized by law, the U.S. government said.

The U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration issued a bulletin reminding operators how to change the status of a pipeline from "active" to "abandoned" as federal regulations do not recognize designations beyond that framework.

"This action makes it clear that PHMSA considers pipelines either active and fully subject to safety regulations, or abandoned, and that pipeline owners and operators are responsible for making sure their pipelines do not pose a threat to people, property or the environment," PHMSA Administrator Marie Therese Dominguez said in a statement.

In 2014, a corroded weld seam on a pipeline led to a minor crude oil spill, about 28 barrels, in Wilmington, Calif. Excavation revealed a pipeline thought to be inactive, but designated incorrectly because it was never purged properly.

More recently, about 28 barrels of an oil-water mixture leaked in October from a pipeline in Cypress, Calif., from a pipeline through to be abandoned in 1997.

Federal regulators designate pipelines as either active and subject to all relevant parts of the law, or abandoned.

PHMSA said it was working "aggressively" to enforce safety measures and reminding operators of the rules to meet that effort.