Officials at the lakeshore closed the beach at Cowles Bog Wednesday, the third beach within the park to shutter because of the chemical spill, though the trails in the area remain open to the public, according to a statement from Bruce Rowe, supervisory park ranger and public information officer for the national lakeshore. The park closed public access to West Beach and the Portage Lakefront and Riverwalk Tuesday afternoon in light of the spill, which an EPA official said occurred Tuesday morning within 100 yards of Lake Michigan.