Litigation that has been under way since 1999 over property damage caused by Kerr Dam may proceed as a class action under a Thursday ruling from the Montana Supreme Court.

With a 5-2 decision, the court overturned the finding by Flathead District Judge Kitty Curtis that the cause of erosion would need to be shown on a property-by-property basis around the lake and on parts of the Flathead River affected by the lake level.

The high court disagreed, saying that damage caused by the dam over the years has to be considered in aggregate, largely because the lake can only be maintained at singular elevations at the dam and elevations cannot be adjusted for particular lakeshore properties.

The court found that “a class action is far superior, for purposes of fairly and efficiently adjudicating the controversy, to innumerable individual lawsuits.”

However, the liability of the defendants — Montana Power Co. and PPL Montana — would have to be determined on a case-by-case basis.

If a jury finds that decisions to maintain the lake at particular elevations at particular times of year  caused aggregate damage to properties that is “unreasonable,” then Montana Power Co. or PPL Montana are subject to liability for those damages, the ruling states.

“The amount of damages, of course, will then be determined on a property-by-property basis,” it continues.

The 44-page ruling, including a dissenting opinion, points out that a jury theoretically could find the extent of erosion around the lake when it is at full pool from mid-June to mid-September is reasonable when balanced against recreational needs of shoreline property owners and businesses, but the degree of erosion occurring when the lake is maintained at full pool into October and November is unreasonable.

The court found that shoreline easements granted to the dam operator after it was built did provide protections for that operator. To suggest otherwise, it states, would hold the operator “hostage to the most geologically fragile shoreline property, which is not a reasonable interpretation of the flood easements.”

The plaintiffs in the case were led by north shore property owner Becky Mattson, who died in July 2010 at age 88.

They alleged that Kerr Dam operations since the dam was completed in 1938 have resulted in an “ever widening footprint” of the lake, with severe erosion being caused when the lake is artificially held at the full pool elevation of 2,893 feet, particularly during fall storms. Before the dam was built, court documents state, the lake reached peak elevations of 2,890 feet.

The case has gone to the Supreme Court for review three times since litigation got under way in 1999, and last week’s ruling defines the lawsuit “class” as anybody who has owned property on the lake or portions of the river since November 1991.

That amounts to about 3,000 properties and could entail multiple owners of each property, said Jamie Franklin, a Chicago-based attorney representing the plaintiffs. “There could be multiple owners associated with the 22 years of those properties. All of those people would be class members,” she said.

“We will be proceeding on behalf of all those people and try to recover any damages they’ve incurred,” Franklin added.

Franklin said he is ready to proceed, and Flathead County District Courts soon will schedule hearings for the coming year. Curtis is retiring so another judge will preside over the case.

Reporter Jim Mann may be reached at 758-4407 or by email at jmann@dailyinterlake.com.