For those hoping to get in one last swim in the Gowanus Canal before summer officially ends, don’t. I Quant NY‘s latest map is an analysis of which waterways in New York are tested as unsafe for swimming the most often. The reason: too much poop.

As I Quant NY’s Ben Wellington explains, when heavy rain occurs, New York’s water treatment plants can’t handle the increased volume of water, and thus a combination of gutter water and sewage overflows into our waterways. The city monitors this problem by testing the water for Fecal Coliform, which is a type of bacteria found in warm blooded animal excrement. If there are more than 1,000 coliform per 100ml of water, then the beach or waterway is closed by the state. 

Using Harbor Water Sampling Data, I Quant figured out which NYC waterways are the poopiest by calculating which were closed the highest percentage of the time. Topping the list are Coney Island Creek, closed 94% of the time and Bergen Basin (near JFK), closed 75% of the time. Next are the Bronx River, Alley Creek and another part of Bergen Basin, destroying our hopes for a quick dip before a flight. Don’t worry, everyone’s favorite disgusting body of water, the Gowanus Canal, makes the top ten.

With these calculations, I Quant NY created an interactive map with the ratings of every waterway measured. Larger circles indicate a higher percentage of time closed, and clicking on a circle will reveal more detailed data.