164,816 documented orphaned wells

WellCensus documents 164,816 orphaned wells — unplugged wells with no responsible operator able to plug them — combining the USGS Documented Orphaned Well Database (130,121 wells in 28 states, 2026 release) with the orphan flags in state registries. Only wells a regulator has recorded and located are counted; estimates of undocumented orphans run into the hundreds of thousands more.

An orphaned well is an oil or gas well that is no longer used, hasn't been plugged and has no operator who can be found or is able to plug it. That is narrower than an abandoned well: "abandoned" describes a well that has stopped being used, and an abandoned well can still have a responsible owner who must plug it. Federal law (42 U.S.C. 15907) defines orphaned wells on federal and tribal land and leaves the definition for state and private land to each state, which is why counts differ between sources. Unplugged orphans can leak methane and contaminate groundwater; plugging them is the target of $4.7 billion in federal funding under the 2021 infrastructure law.

Pennsylvania leads with 27,259 documented orphaned wells in the current inventory.

The Bipartisan Infrastructure Law (2021) appropriated $4.7 billion for orphaned-well plugging — most of it granted to state programs through the Department of the Interior. States also fund plugging through bonding forfeitures and dedicated orphan-well funds.