As expected, the Montana Consumer Counsel has offered a searing critique of NorthWestern Energy's proposal to charge ratepayers $407 million for a long-term share of power generated by the Colstrip 4 power plant.

The Counsel has been critical of the deal, and its star witness before the Public Service Commission, economist John Wilson, ripped into the proposal in testimony he filed last month.

Yet Wilson's attack has been answered by a somewhat unlikely source: retired University of Montana economics professor Tom Power of Missoula.

Power, a stern critic of utility deregulation and a past critic of NorthWestern and its predecessor, Montana Power Co., filed testimony that mostly defended the company and argued that many of Wilson's criticisms are off-base.

Both Power and Wilson are expected to take the witness stand today or Friday before the Public Service Commission, which must decide whether to accept or reject the company proposal. Lawyers from each side will try to punch holes in Power's and Wilson's respective written testimony.

Wilson's 40-page testimony, filed Aug. 8, said NorthWestern last year improperly used some ratepayer money to buy 222 megawatts of power from Colstrip 4, for $187 million.

Now, the company wants to sell that share of power to ratepayers for $407 million, which NorthWestern says is the market value.

Wilson said that price is vastly inflated, that NorthWestern uses misleading figures to argue it's a good deal, and that ratepayers have a claim on the power that entitles them to a lower price.

Power, in his response, said ratepayers never had any claim to the Colstrip 4 power, because the PSC in 1985 refused to let Montana Power Co. put it into the "rate base" and charge customers for its cost.

He also said if Montanans want to rebuild NorthWestern into a utility that owns or operates its own power sources, dedicated to ratepayers, the customers will have to pay the up-front costs of building or buying those power sources.

"As much as we might wish that the relatively low-cost generating resources that Montana Power once owned were still the core of NorthWestern's electric supply, despite Mr. Wilson's suggestions to the contrary, there is no way to regain access to those resources at their original cost," Power wrote.

Power said placing the Colstrip 4 power into "rate base," requiring customers to pay the cost of this power over time, has its risks. But if no commitments are made to place power into the rate base, customers will be exposed to market prices forever, he said.

Except for the Colstrip power, NorthWestern owns no power resources, and must buy electricity for its customers on the open market.