Citing a lack of evidence, a Washington County judge has dismissed a lawsuit against the city of Stillwater over a boy’s death from a rare parasite he caught while swimming in Lily Lake.

But the boy’s father said he plans to appeal the judge’s decision, noting that his son was not the first child to die from an amoeba traced to warm water in the lake, which has a small public beach.

“It’s still not right,” Jim Ariola said Tuesday. “How did they not know about the first case? It was right in their town.”

Ariola’s 9-year-old son, Jack, died in August 2012, two years after Annie Bahneman, 7, of Stillwater died of the same Naegleria fowleri brain infection after swimming in Lily Lake.

The children’s deaths led to a public debate over how local and state governments might detect biological dangers in lakes and streams, and whether they should warn people of a parasite that has caused a comparatively small 133 known infections nationwide in the past 54 years.

In her order last month dismissing Ariola’s suit, Judge Susan Miles wrote that the plaintiff had “failed to identify any other employee or official of the city of Stillwater who had knowledge of any condition at Lily Lake that was likely to cause serious bodily injury or death.”

She wrote that the city administrator, engineer and public works director all testified in depositions that before Jack’s death they had no knowledge of Annie’s death or that Lily Lake contained the Naegleria fowleri amoeba.

“The record is devoid of any evidence … drawing any link between these city officials and test results or information relating to [Naegleria fowleri],” she wrote.

But Ariola’s attorney, Roger Strassburg, said Tuesday that Miles erred in choosing “to believe city officials when they said they didn’t read the papers.” Given extensive media publicity, he said, their ignorance of Annie’s death was hard to believe.

Ariola, of Wyoming, Minn., alleged in his suit that city officials altered the bottom of Lily Lake to create a shallow area, resulting in warm water uniquely favorable to the Naegleria fowleri amoeba.

The microscopic amoeba, invisible to the human eye, enters the nose and travels to the brain, where it kills tissue and causes inflammation and death.

Annie’s death was the first in Minnesota from the illness — a form of meningitis — and probably the first in a northern state, the Minnesota Department of Health said at the time. She died four days after becoming sick.

Jack fell ill while camping with his mother and other family members on the North Shore of Lake Superior. He died in a Duluth hospital.

At a public meeting in Stillwater after Jack’s death, a state health official said many Minnesota lakes could have the parasite — particularly in prolonged stretches of summer heat — and that it can come and go unpredictably.

Strassburg, who is based in Scottsdale, Ariz., said he’s represented four other Naegleria fowleri cases outside Minnesota and “settled them favorably for the client.” But Minnesota has immunity laws “very protective of government,” he said, despite private enterprises being held more accountable for operating splash pads and public swimming pools.

Of the 133 known infected people nationwide, only three survived, according to the U.S. Centers for Disease Control. Their median age was 12, and most infections occurred in southern states.

One of the unconfirmed cases in Minnesota involved 11-year-old Hailee Marie LaMeyer of Stacy, who died in 2008 after swimming in Fawn Lake near her home. Her mother, Heidi, said Tuesday that the circumstances of her death mirrored those of Annie and Jack, but complications with testing her spinal fluid prevented a conclusive cause of death.

“I just want people to know this could happen to them. Don’t think it couldn’t,” Ariola said Tuesday. “If I had only known, he would not have swam there. My little boy will never swim in a lake, ever again.”