Minnesota Power said it will likely spend more than $500 million to accommodate the requirements. The utility provides electricity to 143,000 people within a 26,000-mile area in northeastern Minnesota.

The ruling further requires the company to pay a $1.4 million penalty and at least $4.2 million on environmental projects to benefit local communities. The state of Minnesota is co-plaintiff in the lawsuit and will receive $200,000. In addition, the company must retire, refuel, repower, or reroute emissions at five other units, while meeting emission rates and installing additional control technologies at remaining units.