This east-looking, low-oblique photograph shows Lake Okeechobee, the fourth largest lake wholly within the United States. Covering an area of 700 square miles (1815 square kilometers), the lake is 35 miles (55 kilometers) long and as wide as 25 miles (40 kilometers). The maximum depth of the lake is slightly more than 15 feet (5 meters). Lake Okeechobee receives the Kissimmee River from the north and drains to the ocean through the Everglades. In the 1960s, the Kissimmee River was shortened and channeled, and the lake was encircled by a huge dike to prevent its annual overflow. The areas around the lake were drained and crisscrossed by a network of canals, dikes, and raised roads. Hundreds of thousands of acres (hectares) were put under intensive cultivation to produce vegetables and sugarcane. Since the 1960s, Lake Okeechobee has become a giant septic tank for runoff wastes and pesticides, yet it continues to serve as a holding pond for water that is now rationed to the Everglades. The whole ecosystem of the Everglades and the Big Cypress Swamp has been altered, resulting in severe damage. Recent developments have allowed the Kissimmee River to flow once again in its natural channel, and processes are under way for the cleanup of Lake Okeechobee.