You might be surprised to learn what swims through America’s cities. Even waterways with a history of pollution are full of life and are vital parts of local communities. Coastal Superfund sites, where hazardous waste contaminates the environment, are one of the key sources of pollution for many urban waterways. Many American cities sprang up around waterways because they provide opportunities for transportation, trade, and industry. Unfortunately, many of these industries also release contaminants into the environment—where they can linger for decades.