A Washington farm couple who bought riverfront pastureland in 1993 can’t sue an electric utility for flooding allegedly caused by a hydropower dam built in 1955, the Washington Supreme Court ruled Aug. 3.

The unanimous ruling overturned a lower-court decision that public utilities and transportation officials warned would allow claims against old transmission lines, highways and other public works.

Brock and Diane Maslonka asserted flooding has gotten worse since they bought land along the Pend Oreille River in northeastern Washington to grow hay and raise cattle. An appraiser said the flooding devalued their property by about $288,000.

While the appeals court said it was “not inconceivable to think” the dam was to blame for the new damage, the high court said that was too speculative.

Without a evidence of a “new taking” by a government body, the Maslonkas did not have standing to sue the dam’s owner, the Pend Oreille Public Utility District, the court ruled.

“The Maslonkas produced no evidence that the dam’s operations changed after 1993 to increase flooding; any increase cannot be, on this record, attributed to the PUD,” Justice Susan Owens wrote for the court.

Efforts to obtain comment from the Maslonkas were unsuccessful.

The Maslonkas were aware water backed up behind Box Canyon Dam and sometimes flooded the property when they bought it, according to court records.

The PUD denied any change since 1993 in how the dam was operated that would cause more flooding. A Pend Oreille County Superior Court judge agreed and dismissed the Maslonkas’ claim.

The Court of Appeals Division III reinstated their lawsuit. To be exempt from the Maslonkas’ claim, the PUD had to prove its dam was doing as much damage before 1993 as after, the appeals court ruled.

The Washington Public Utility Districts Association and Washington Department of Transportation argued in amicus briefs that the appeals court had upset the legal doctrine that landowners can’t sue a public agency over conditions that existed before they purchased the property.

The appeals court decision, if left in place, would force agencies to defend claims against old transmission lines, highways and other public works, they warned. “The costs of those claims will ultimately be borne by the public,” according to the PUDs.

The Pend Oreille PUD obtained easements from riverfront landowners in the 1950s and 1960s to compensate them for raised river levels. The river level sometimes exceeds the easements.

The right to inverse condemnation — suing government for taking private property — belongs to the property owner at the time of the taking, Owens wrote.

The right does not pass to a subsequent purchaser unless expressly conveyed, she stated.