Both federal US authorities and Alaskan state officials have given up efforts to recover $92m in damages from ExxonMobil for some environmental and wildlife cleanup costs associated with the notorious Exxon Valdez oil tanker spill of 1989, according to the Associated Press and Reuters.

The announcement came in court filings where Justice Department and Alaskan state lawyers accepted that patches of lingering oil can no longer be considered an impediment to the recovery of sea otters or harlequin ducks or a significant ongoing threat to their now-restored populations.

The spill occurred in Alaska’s Prince William Sound when the Exxon Valdez ran aground and spilled 11 million gallons of crude. It led to a $900m settlement in 1991.

In 2006 the authorities invoked a “reopener” clause of the settlement that allowed for the governments to seek additional funds for restoration projects. That is the door that is now being closed.