Federal wildlife officials can’t do much but watch as waterfowl in Wisconsin die from an intestinal parasite — a tiny creature they fear may soon cross into Minnesota and Iowa. Jim Nissen, a spokesman for the U.S. Fish and Wildlife Service, says the infections are limited right now to Wisconsin’s Lake Onalaska. Nissen says “The Mississippi River borders the two states and the habitat the birds are using is Lake Onalaska…but it’s not to say that the birds move down river and start using favorable habitat in Minnesota and Iowa.” The waterfowl die after eating snails infected with the parasite. The deaths began in mid-September but were also seen on Lake Onalaska during migrations this spring and last fall. Nissen says they’re monitoring the situation because there’s not a lot they can do:Nissen says “You’re not going to go out and remove the snails. We have a lot of them out here and it’s really hard to determine where in the lake, if they’re getting them there, where at and then what you can do about it.” Lake Onalaska is a backwater lake on the Mississippi River, just north of LaCrosse, Wisconsin.