The Oregon Supreme Court didn’t rule Thursday on a central question posed to it in a lawsuit: Is Oswego Lake -- the 405-acre body of water in the center of this ritzy suburban community -- open to the general public or is it a private playground for the rich who own nearly every inch of its shorefront?

The high court sent back to a lower court judge the question of whether Oswego Lake legally qualifies as a “navigable waterway."

If it does, the Supreme Court said the lower court judge -- a Clackamas County Circuit judge -- must decide whether the city of Lake Oswego is being unreasonable by forbidding members of the public from wading, swimming or boating from a small piece of waterfront property that it owns, Millennium Plaza Park.

Signs at the park say the lake is private and warn the public to stay on land. Those who have tried have been asked to leave or threatened with a ticket.

Although the plaintiffs and defendants had hoped to settle the question once and for all, the 41-page written ruling failed to end many decades of debate over who can use the lake.

The Supreme Court was asked to decide on a 2012 lawsuit brought by kayaker Mark Kramer and open water swimmer Todd Prager who don’t own lakefront property and have been barred from recreating on Oswego Lake. They asked the high court to overrule previous decisions by the Clackamas County Circuit judge and the Oregon Court of Appeals that denied them access.

During arguments before the court in May 2018, a lawyer representing Kramer and Prager said the case is about the right of the people to use and access all navigable waters in the state -- not just Oswego Lake.

"It's about the quality of life of all Oregonians," attorney Thane Tienson said.

But, asked Justice Rives Kistler: “What if the lake is surrounded entirely by private property? ... Must public access be granted?” Kistler, who retired in December, didn’t end up participating in Thursday’s decision.

In this file photo, sunken steps lead into the green waters of the lake, but a sign greets human visitors at Millennium Plaza Park not to step foot into the lake because it's private. (The Oregonian/2001)The Oregonian/File photo

The Lake Oswego Corp., the nonprofit entity that has managed the lake since 1942, argues that the entire lake is private. Nearly 700 lakeshore landowners pay yearly dues for the lake’s upkeep. Another 3,400 property owners who don’t live on the lake have access to it through about 20 private easements, for which they also pay dues.

Waterfront homes frequently sell for multiple millions each. Currently, five homes are on the market with asking prices around $5 million or more. Only one vacant lot is listed -- at $795,000, and it comes with plans to build a tram to carry its new owners down a narrow slope to a private boat dock on the water.

In 2012, the City Council passed a resolution banning the public from accessing the water from city lands.

In addition to Millennium Plaza Park, the city also owns another piece of property with access to Oswego Lake: the Lake Oswego Swim Park. The city has argued that it lawfully restricts use of that park to Lake Oswego residents because only their tax dollars pay to maintain it.

Unlike Millennium Plaza Park, the swim park is fenced off on all sides. A fence and gate restrict access from the road. Once inside the park, swimmers are prevented from entering the open waters of the lake by fences along the docks that essentially wall off access to the main lake from the park.

The Supreme Court noted Thursday that under the “public trust doctrine” the state owns the land underneath bodies of water, but only if those bodies of water are “navigable.” That’s what the Clackamas County Circuit judge must decide.

Bodies of water historically have been assumed navigable if people can achieve passage by boat from one place to another or if they’ve been used for industry, such as by the fisheries industry or for moving logs down river.

The lake is fed by the Tualatin River and is dammed at one end, but water flows out of it and into the Willamette River.

If the judge agrees that Oswego Lake is navigable, the Supreme Court ruled that the public has the right to access the lake by traversing over public land, including the city-owned land of Millennium Plaza Park.

However, the Supreme Court found that the city could prevent the public from getting to the water through that park if it puts forth some “objectively reasonable” rationale for that.

The city has argued that it has health, safety and environmental concerns about allowing people to enter the lake from Millennium Plaza Park. Those concerns include the safety of people who might swim off the park’s shores even though there are no lifeguards on duty.

Tienson, the lawyer for the plaintiffs, disputes that the lack of lifeguards is a chief concern because the city owns other parks on the Willamette River where visitors swim without lifeguards present. Among them is George Rogers Park, where a beach has no fencing barring the public from wading into or swimming in the river. The city’s website also advertises public boat access from those parks.

Tienson said sees the Supreme Court’s ruling as an overall victory. He doesn’t think the city can successfully argue that it’s reasonable to forbid access to the lake from its property, given that no other way exists for the public to get to the lake.

“By definition, it’s unreasonable," Tienson said. “You cannot block all public access."

The city of Lake Oswego declined immediate comment through its attorney David Powell, who said city officials are still reading through the lengthy opinion and the City Council hasn’t had time yet to discuss it.

Jeff Ward, general manager for the Lake Oswego Corp., declined to discuss the legal arguments in the case but said the organization will continue to advocate its position when the case returns to Clackamas County Circuit Court.

-- Aimee Green

agreen@oregonian.com

o_aimee

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