Martin Woess and his aquatic weed harvester dubbed the Lake Mess Monster has been busy clearing the waters of Prospect Park. Once a week Woess climbs aboard his weed harvester to collect the scum which consists mostly of duckweed and azolla which would quickly take over the pond if left unchecked. New York City owns two of these specialized boats the other is in service at Central Park’s Harlem Meer.
Greenish growths on lakes, ponds and rivers are common across the U.S., typically blamed on excess nitrogen in runoff water carrying fertilizer from farmland. The problem in Prospect Park and Central Park is different: the artificial lakes and ponds, designed by Frederick Law Olmsted and Calvert Vaux, are filled with the same water that New Yorkers drink. The potassium-enriched tap water helps the scum flourish. The mild winter and hot summer have exacerbated the problem this year.