Swimmers will not be able to hit the beach at a popular northeast Iowa waterhole during this last holiday weekend of summer. D-N-R spokesman Ross Harrison says high bacteria levels have forced the closure of the beach at George Wyth State Park near Waterloo. He says bacteria levels seem to increase as they get a good crowd on the beach. Harrison says the rest of the lake still has good levels, so they’re trying to figure it all out.Harrison says swimming will be permitted at Clear Lake State Park in northern Iowa, but warning signs have been posted there due to elevated bacteria levels.Another northeastern Iowa state park, Backbone, is in the same boat as Clear Lake due to bacteria levels. Harrison says Backbone, in Delaware County, has also had warning signs posted for swimmers. He says Backbone has gone up and down in its readings due to a large watershed.Harrison says the lake at George Wyth will be closed at least a week.