Hydrilla distribution map
Image by EDD Maps

Hydrilla EDDMapS Distribution.

Where Else Is Hydrilla Found?

The Great Lakes Hydrilla Collaborative is now tracking where hydrilla.  See their 


For historical purposes the original material gather by the Cayuga Lake Watershed Hydrilla Task Force is still available here. 

New York State


A new infestation of hydrilla was discovered in September 2016 in Aurora, NY, adjacent to Wells College shoreline. This new discovery was made by the volunteers aboard the Cayuga Lake Floating Classroom. FL-PRISM, Cayuga Lake Watershed Network, Cayuga County, Hydrilla Task Force, and other interested parties coordinated in October 2016 to conduct an extensive survey and delineation of new infestation. Stakeholders will collaborate to develop a management strategy for the 2017 season.


A new infestation of hydrilla was discovered in fall 2015 in Tinker Nature Park, located near Rochester, NY (Monroe County). This discovery was made by Hilary Mosher, Coordinator for the Finger Lakes Partnership for Regional Invasive Species Management (PRISM). Tinker Pond is a small, isolated pond with no inlets or outlets. Response efforts involve stocking of triploid grass carp (2015) and installation of benthic barriers (2016).


A new infestation has been found in Brooklyn's Prospect Park Lake in June 2014. Since the lake is 20 miles from the nearest infestation, water fowl seem to be the likely culprits of transporting hydrilla. The Creamery Pond treatment described below has received another grass carp stocking.


A new infestation of hydrilla was discovered in October 2013 in the Croton River, in Westchester County, NY (2). The hydrilla was already well-established, and both floating and rooted hydrilla were present. NYS DEC has already begun an interagency response, and will determine a response plan that will fully survey the infestation, consider options for treatment, and educate the public. By November 2013, the Croton River infestation had reached the mouth of the Hudson River.

Before 2013

Cayuga Inlet (187) was the first finding of hydrilla in upstate New York (Aug. 2011). In September 2012:  Hydrilla was found near the Erie Canal in North Tonawanda (151). More detailed map of the infested area of Tonawanda Creek. Small isolated ponds in Broome County (3)

Before 2011, hydrilla had infested 8 isolated lakes downstate. For a variety of reasons, the DEC's response in NYS has largely been containment, rather than trying to eradicate the plant. The exception is Creamery Pond in Orange County (2), which was treated with fluridone/copper followed a couple of years later by stocking of grass carp.

In most of the untreated lakes, it is hard to know much about how it spread, since there is little or no information about these small bodies of water before the infestation was discovered. According to Kishbaugh, "The best information is for Lake Ronkonkoma, the other 'significant' waterbody with hydrilla. We have decent pre-infestation data, and a pretty good idea that the 2009 hydrilla finding was probably within a year of infestation. Prior to hydrilla, the lake was essentially devoid of vegetation.

"In 2009, hydrilla was moderate in 5% of the locations, sparse in 35% of the locations, and trace in 35% of the locations," he says. "All other plants were sparse in 5% of the locations and trace in 40% of the locations (no plants were found in the littoral zone in about 30% of the locations). In 2010, hydrilla was dense in 10% of the locations, moderate in 30% of the locations, sparse in 40% of the locations, and trace in 10% of the locations (and not found in 10% of the locations). All other plants were no more than trace in 25% of the locations. Hydrilla densities dropped a bit in 2011, but still constituted more than 95% of the plants in the lake."


Last updated October 5, 2020