The Gowanus neighborhood was once a system of tidal creeks winding through a salt marsh and fed by freshwater streams. These creeks were dammed to build tidal mills, and then dredged and channelized into a one of the busiest waterways in America, bringing goods into the growing city. By the time the Gowanus Canal was complete in 1869, its banks were home to a number of industries, including manufactured gas plants, foundries, coal yards, and ship yards. Over the course of the 20th century, these uses contributed to pollution in and around the Gowanus Canal. This historic contamination along with ongoing combined sewage overflow (CSO) into the Gowanus Canal lead to its designation as an US Environmental Protection Agency (EPA) Superfund site in 2010.