ALBUQUERQUE, N.M. - New Mexico is suing the state of Colorado, saying its neighbour to the north should be held responsible for the contamination caused by the 2015 Gold King Mine spill as well as decades of acidic drainage from mines near the headwaters of the Animas River.

The New Mexico Attorney General's Office and the state Environment Department announced late Wednesday that they filed a complaint against Colorado with the U.S. Supreme Court.

It marks the second major legal salvo fired by New Mexico in the wake of the August 2015 spill, which fouled rivers in three states with a yellow soup of arsenic, lead and other heavy metals. New Mexico is also suing the U.S. Environmental Protection Agency.

Colorado officials have previously declined to comment on New Mexico's claims, citing possible litigation.