OSHKOSH, WI (WTAQ) - Shells from the invasive zebra mussel are piling up along Lake Winnebago – and they’ve closed up at least one small channel near Oshkosh. Folks who live along the channel are frustrated, because they cannot move their boats through the inlet and onto Lake Winnebago. The mollusk shells are only about the size of a fingernail – but there are literally millions along the lake. And at the channel, they’re created a barrier several feet high. The mollusk walls are keeping boats, fish, and even fresh water from passing through the channel and into Wisconsin’s largest inland lake. Ron Bruch of the state DNR said the mussels were brought in by boats on the Great Lakes. They were first discovered in the Lake Winnebago system in 1998, and their numbers peaked early last decade. There are large walls of zebra mussel shells at various spots around Lake Winnebago, to both the west and east. Bruch says they’re impossible to deal with, and all folks can do is live with them.