A long-running private property dispute on the St. Croix River ended Friday when the U.S. Supreme Court ruled against a Wisconsin family that wanted to sell a small plot of shorefront land to finance improvements on their adjacent cabin.

The 5-3 decision rejected the Murr family's argument that conservation rules unfairly stripped their land, south of Hudson, Wis., of its value.

Justice Anthony Kennedy, joining the court's liberal members, called the government's action "a reasonable land-use regulation" meant to preserve the St. Croix River and surrounding land.

Donna Murr, one of the four siblings who brought the case forward, said the family was disappointed.

"It is our hope that property owners across the country will learn from our experience and not take their property rights for granted," she said.

Although the buildable land in dispute covers less than one acre, the case of Murr vs. Wisconsin and St. Croix County quickly hit the national stage because of similar conflicts in other states.

The Murrs and their attorneys had alleged overregulation of personal property, arguing that because governments can view two contiguous parcels as a "parcel of the whole," property owners are denied compensation for one of them.

From the other side, St. Croix County said that granting the Murrs an exception to laws protecting the St. Croix River would weaken the government's ability to guard against overdevelopment anywhere on the river.

Remzy Bitar, an attorney representing St. Croix County, said Friday that county officials were pleased with the "clean and important win" and said the high court ruling left no significant issues unaddressed.

The ruling balances land-use decisions with safeguarding of "the nationally treasured scenic riverway," he said.

Writing for the court majority, Kennedy said that the Murrs had not suffered a regulatory taking of their property and "have not been deprived of all economically beneficial use of their property."

In dissent, Chief Justice John Roberts wrote the court majority had undermined the Constitution's protections for private property owners. Roberts said the court should have relied on state property lines to define the relevant parcel of land rather than consider outside factors.

More than 100 cities and counties across the United States have similar merger restrictions that treat two adjacent properties as one if they have the same owner.

The dispute began in 2004 when the Murrs tried to sell the vacant lot to pay for improvements on their family cabin, in Troy Township, that sits on the plot next door.

Their father had purchased the two 1.25-acre lots separately in the 1960s and both parcels had been taxed separately. The lots were later transferred to his children in the 1990s.

County officials blocked the sale, citing 1976 regulations that bar new shoreline construction to prevent overcrowding and pollution on the St. Croix, which is protected under the U.S. Wild and Scenic Rivers Act.

The Murrs sued Wisconsin and St. Croix County for payment of what the vacant property was worth — it was assessed at $400,000 — but Friday's Supreme Court ruling means the family won't receive any compensation.

"This is an unfortunate decision for the Murrs, and all property owners," said John Groen, an attorney with the Pacific Legal Foundation who represented the family for free. "We are disappointed that the court did not recognize the fundamental unfairness to the Murrs of having their separate properties combined."

The Associated Press contributed to this story.

Kevin Giles • 651-925-5037