WATERVILLE — Colby College has reached its goal of being carbon neutral.

Colby says that as of Thursday, it has a net zero carbon footprint through a combination of minimizing greenhouse emissions and using carbon offsets to mitigate the remaining emissions.

The liberal arts school in Waterville says it’s the fourth college nationwide to achieve carbon neutrality, reaching the mark two years ahead of the target it had set for itself.

Colby officials say the school has cut emissions by about two-thirds in the past decade, through a number of initiatives that include switching to 100 percent renewable electricity and using wood biomass instead of oil for heat and hot water.