DULUTH — State regulators agree Minnesota Power does not need to conduct a major environmental review before retrofitting a coal-fired plant in Cohasset.

The Minnesota Public Utilities Commission decided Thursday that installing new pollution control equipment at the Boswell 4 plant does not require a full environmental review.

The power plant is the Duluth-based utility’s single largest unit. The plant is slated to receive $350 million in upgrades to make it compliant with state and federal air pollution regulations, especially for mercury emissions.

Environmental groups say the money would be better spent phasing out the coal-fired plant and instead building new, renewable electric sources.

Minnesota Power said that’s not a viable option.