"Pollution is destroying their habitat -- they're an endangered species," says Carrie Gishman, chairwoman of the Save the Sewer Gators Coalition.
"Studies show an alarming drop in the alligator population, from an estimated high of 11,000 in 1971 to fewer than 600 today," Ms. Gishman said.
Scientists say that from the 1930s through the 1960s, New Yorkers returning from vacations in Florida brought back cute, cuddly baby alligators as souvenirs -- then flushed them down the toilet when the reptiles grew bigger and started snapping. Those that survived bred in the bowels of the vast sewer system.
Although it's often been erroneously dismissed as an urban legend, sewer inspectors confirmed the existence of the hardy reptiles -- some as long as 11 feet.
"They rarely harm humans," says Ms. Gishman. "They feed chiefly on rats, helping to control the city's rodent population and maintain the ecosystem balance."
A major obstacle confronting the activists is that New York officials, concerned about tourism, refuse to publicly acknowledge the endangered alligators even exist.
"If they continue to ignore this crisis, in a few years there won't be a single alligator left in the New York sewers," warns Ms. Gishman.