A Vermont-based landfill operator must pay $50,000 to a conservation trust and remediate at a Bethlehem landfill to end a federal suit brought by environmental advocacy groups.

The suit was filed in 2018, with advocacy organizations Toxics Action Center, Inc., and the Conservation Law Foundation alleging that Casella Waste Systems had violated the Clean Water Act when part of its Bethlehem landfill leached contaminated fluids into groundwater that filtered into the nearby Ammonoosuc River.

The spill in Bethlehem has been cited by residents of Dalton who oppose a Casella-owned landfill proposed for that town.

Casella argued in a motion to dismiss the suit that they were not responsible for the landfill, and that the advocacy groups did not have standing to sue. A judge denied that motion in 2018. After four years of motions and delays, including an earlier attempt at mediation, the environmental groups and the landfill operators settled this week.

The settlement requires Casella to remove contaminated soil from a drainage channel and repair the channel, with work to be completed within the next three years.

Casella must also pay $50,000 into the nonprofit Amonoosuc Conservation Trust, for preservation and recreation of the Ammonoosuc River.