Channel are entered from the east. The East River is a broad strait that travels north to Newtown Creek and the Harlem River, turning east at Hell Gate before opening to Long Island Sound, which provides an outlet to the open sea. Channels The port consists of a complex of approximately of shipping channels, as well as anchorages and port facilities. Most vessels require pilotage, and larger vessels require tugboat assistance for the sharper channel turns. The Ambrose leads from the sea to the Upper Bay, where it becomes the Anchorage Channel. Connecting channels are the Bay Ridge, the Red Hook, the Buttermilk, the Claremont, the Port Jersey, the Kill Van Kull, the Newark Bay, the Port Newark, the Elizabeth, and the Arthur Kill. Anchorages are known as Stapleton, Bay Ridge and Gravesend. The natural depth of the harbor is about , but it was deepened over the years, to a controlling depth of about in 1880. By 1891, the Main Ship Channel was minimally deep. Following the Rivers and Harbors Act of 1899 over $1.2 million of initial funding was appropriated for the dredging of 40 ft (12.2 m)-deep channels at Bay Ridge, Red Hook, and Sandy Hook. In 1914, Ambrose Channel became the main entrance to the port, at deep and wide. During World War II the main channel was dredged to deep to accommodate larger ships up to Panamax size. In 2016, the Army Corps of Engineers completed a $2.1 billion dredging project, deepening harbor channels to in order to accommodate Post-Panamax container vessels, which can pass through the widened Panama Canal as well as the Suez Canal. This has been a source of environmental concern along channels connecting the container facilities in Port Newark to the Atlantic. PCBs and other pollutants lay in a blanket just underneath the soil. In June 2009 it was announced that 200,000 cubic yards of dredged PCBs would be "cleaned" and stored en masse at the site of the former Yankee Stadium and at Brooklyn Bridge Park. In many areas the sandy bottom has been excavated down to rock and now requires blasting. Dredging equipment then picks up the rock and disposes of it. At one point in 2005, there were 70 pieces of dredging equipment working to deepen channels, the largest fleet of dredging equipment anywhere in the world. The channel of the Hudson is the Anchorage Channel and is