The Montana Public Service Commission on Tuesday approved Hydro One’s acquisition of Avista Corp., which serves as part owner the Colstrip generating facility.

In its 4-1 vote, the commission added several conditions it says are intended to protect public interest and the continued operation of the coal-fired generating facility.

“Even though they only have 32 people being served, they’re a large taxpayer and job creator,” Commissioner Bob Lake, R-Hamilton, said in a statement provided by the PSC. “Because it’s a Canadian company, that causes greater concerns, but their history of quality and reliable service made the decision easier.”

Hydro One Limited is looking to acquire Avista Corp., a utility that supplies electricity and natural gas in Montana and several other states.

Avista has just 32 customers in Montana, but owns a 15 percent stake in Colstrip units 3 and 4, as well as hydroelectric assets in Montana, according to Bowen Greenwood, communications director for the PSC.

Because Avista serves customers in multiple states, the merger must be approved by several state utility commissions, including Washington, Idaho, Oregon, Alaska, along with federal agencies.

As part of that approval process, Greenwood said, Avista and Hydro One have reached settlements with various parties in those states. The settlements include an accelerated depreciation schedule for Colstrip units 3 and 4 with an end-of-useful life date of 2027.

The accelerated depreciation schedule caused some Montana commissioners to express concern that it might result in Colstrip’s premature retirement, Greenwood said.

In order to protect against any risk of early closure, the PSC’s resolution opts out of the 2027 depreciation schedule for rate-making purposes in Montana.

Commissioner Tony O’Donnell, R-Billings, opposed the sale.

“On the one hand, there’s the funding for Colstrip’s community transition fund,” he said. “But on the other hand, I didn’t hear enough assurance that the Canadian government can’t interfere to shorten the length of Colstrip power plant’s operational life.”