The Supreme Court of Canada ruled on Thursday that bankrupt oil and gas companies in Alberta must use funds to reclaim oil and gas well sites before paying debtors.

The case, Orphan Well Association v. Grant Thornton Ltd, involved oil and gas company Redwater that went bankrupt in 2015. The trustee in the bankruptcy attempted to disown several non-producing sites and avoid paying clean-up costs. Out of 84 wells, seven facilities and 36 pipelines, the trustee sought to disown all but 17 wells, three facilities and 12 pipelines.

The Alberta Energy Regulator requires that licenses for extracting, processing, or transporting oil and gas include an obligation to plug and cap wells, dismantle surface structures, and restore the surface to its previous condition. Grant Thornton argued that the obligations for site clean up were an unsecured debt, and should only be paid after all secured debtors were paid. The regulator ordered Grant Thornton to cleanup the abandoned sites.

The court determined that the cleanup obligations were not debts, but instead duties of Redwater. The regulator was not considered to be a creditor because the regulator was not the entity that receives payment and the province does not gain financially from meeting the obligations. Instead, the “public is the beneficiary of those environmental obligations.” Therefore, the cleanup obligations were outside of the bankruptcy payment order requirements.

The trustee has already sold or transferred all of Redwater’s assets. The money obtained must now be used to cleanup the abandoned well sites before other debtors can be paid.

Gas and oil wells have been a growing environmental concern in recent years. In September the US Environmental Protection Agency announced plans to reduce monitoring requirements for well sites. In November 2016 the US Bureau of Land Management enacted regulations that would reduce the amount of natural gas that is wasted during production on Federal and Indian lands.