But people still go fishing there.

The Wall Street Journal has a great profile on Martin Woess who cleans the surface of Prospect Park Lake using a special boat that "resembles a John Deere harvester crossed with an old-time paddle steamer" and is called the Lake Mess Monster. Each week, Woess mounts this monstrous machine—which is "not like a lawn mower at all"—and continues the Sisyphean task of keeping the lake clean.

The Journal reports that "clearing the lake takes most of the day" and that if Mr. Woess is out sick? "We wait until I feel better," says the parks employee.

Although Woess has found many things on the surface of the water that are not indigenous to this habitat, things like condoms and "a 3-foot-tall doll of Elmo, the 'Sesame Street' character," the real problem is the rampant growth of plants like duckweed and the especially dangerous azolla caroliniana that are flourishing on the surface of the lake.

The lake in Prospect Park is particularly susceptible to this kind of plant growth because it is filled with good old NYC tap water, which is potassium rich and helps plants like azolla flourish. The WSJ says, "if the scum isn't skimmed, it will eventually get so thick and heavy that it will to sink to the lake bed, where it will proceed to rot. This triggers a problem called eutrophication, in which the water becomes so toxic that it can kill off flora and fauna."

And that would be awful. Everything would be dead and the lake would become a pit full of empty Four Loko cans and Zigzag packages.

Stay healthy, Mr. Woess! You're the last line of defense in the war against turning the lake into a 60-acre version of an NYU student's garbage can.

Follow Kristin Iversen on twitter @kmiversen