State officials say a northeast Iowa lake isn’t safe for swimming.Iowa Department of Natural Resources officials say high levels of fecal bacteria were detected in Backbone Lake near Strawberry Point. The levels were high enough to close the beach at the lake, but state officials say reactions to beach closings last year in Clear Lake prompted them to keep the Backbone beach open. The D-N-R says the cold water may’ve kept swimmers out of the contaminated water. They’re trying to determine the source of the bacteria.