The swimming area and beach at Lyons Ferry Park reopened Thursday afternoon after test results showed the water was again safe.
They had been closed since Aug. 1, when a water sample showed that fecal bacteria exceeded levels considered safe for people.
"The reduction in those bacteria levels this week is likely because of recent cooler temperatures and increased wind through the Snake River gorge," said Darren Opp of the Army Corps of Engineers. That had water moving faster through the swimming area and flushed out contamination, he said.
An open-water swim from the Lyons Ferry Park to the Lyons Ferry Marina will proceed as planned at 11 a.m. Saturday. It is a fundraiser for the Dayton and Pomeroy swim teams. For more information, go to sites.google.com/site/swimthesnake.