“I have not heard of anybody seeing rays in the creek before,” said Willis Elkins, executive director of nonprofit the Newtown Creek Alliance. A group of rays — also known as a “fever” — was spotted swimming through Newtown Creek, a notoriously filthy estuary of the East River, last weekend. Newtown Creek, which runs between Brooklyn and Queens, is among America's most polluted waterways. But since Newtown Creek was declared a Superfund site in 2010, much work has been done to clean its squalid shores. “The whole group swimming as one was really awesome to witness.”