BOISE — Idaho property taxpayers could get stuck with repaying up to $11.6 million if state Supreme Court justices side with a utility, state officials said Wednesday.

Rocky Mountain Power parent PacifiCorp contends that state appraisers inflated the value of their turbines, transmission lines and office buildings, resulting in higher tax bills.

PacifiCorp won a lawsuit over the issue in 2010, and Idaho Supreme Court justices could rule this year on the state Tax Commission's appeal. Idaho Power Co., the state's biggest utility, has also appealed recent appraisals that will likely be impacted by the case's outcome.

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If justices side with PacifiCorp, Idaho taxpayers could see higher assessments or new taxes as counties, fire departments and other taxing districts scramble to repay money collected from the utilities.

Ada County could have to repay $1.8 million, and Bannock County may have to come up with nearly $1 million for the utilities, according to state Tax Commission estimates.

In Idaho, operating properties such as power lines, gas pipelines and railroads are assessed centrally by the Tax Commission as a single unit — not separately by each county like real property.