Ick, ew, gross. Someone has illegally dumped waste from port-a-potties into Four Mile Run Stream near Westover Park in Arlington County. Arlington Alert sent out warnings earlier today telling residents not to fish in or have any contact with the waters – including wading or swimming – until further notice. The Post has a story up about the dumping, and quotes an Arlington parks official describing water near the spill as “blue, crummy and yucky…