Thirsty? If you're in the New York area, there's a 1.8-mile canal conveniently located in the midst of Brooklyn's most expensive neighborhoods that you're welcome to dip a cup into. Provided you're not concerned about puking up blood, suffering explosive diarrhea, or vastly increasing your risk of cancer.

Those are among some of the ailments one might incur upon sipping water from the Gowanus Canal, a brackish, notoriously polluted waterway that connects Upper New York Bay to Brooklyn's interior. In an investigation for Popular Science, Dan Nosowitz set out to determine what would happen if he consumed some of the canal's noxious elixir. As he tries to answer that question, Nosowitz also recounts how the waterway got so darn gross, what exactly is lurking down below, and what the federal government needs to do to fix it.