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What is Hydrilla?

  • Hydrilla (Hydrilla verticillata) is an invasive submersed aquatic plant, originating from Europe and Asia, that has infested Cayuga Lake and other water bodies in the Finger Lakes Region
  • Hydrilla is a perennial plant with noticeably toothed leaves that often grow in whorls of three to eight, usually five

    A closeup of Hydrilla, notice the “teeth” at the edges of the leaves

  • Hydrilla spreads quickly and grows in dense stands that out-compete native species and negatively affect the aquatic ecosystem
  • Hydrilla can clog waterways and hinder recreational activities including boating, fishing, and swimming
  • Hydrilla is commonly spread by boating and fishing equipment. Therefore, education and stewardship are the best management strategies to prevent its spread












Email FLXplantID@gmail.com for printed copies of these posters! PDFs are available for download at the bottom of this page.













Hydrilla has been reported previously in our region in Monroe, Cayuga, Tompkins, Broome, and Tioga Counties (http://www.dec.ny.gov/animals/104790.html), with the Tompkins County infestation being particularly widespread. This infestation has been the focus of significant removal efforts since 2011, and in October 2016, another Hydrilla infestation approximately was found 35 km north of the Tompkins County infestation, close to Aurora in Cayuga County. Treatment and monitoring has been conducted by the United State Army Corp of Engineers (USACE) in collaboration with local stakeholders and partners. Since 2016, two additional Hydrilla populations were detected on Cayuga Lake at private marinas, and another at a private pond in Tioga County.

Map with extent of Hydrilla

Data taken from iMapinvasives. Absence of data does not necessarily mean absence of the species at that site, but that it has not been reported there. For more information, please visit iMapInvasives.


Plants caught in a prop. Always make sure to check your prop before and after launching your boat to stop the spread!

Hydrilla is a notoriously difficult plant to control, given that any piece of the plant that breaks off can grow to create an entirely new plant. That does not mean that it is impossible to control however. Several methods have been used to control Hydrilla, each with their own strengths and weaknesses, these include:

  • Herbicides
  • Benthic Mats
  • DASH (Diver Assisted Suction Harvesting)
  • Dredging

The FL-PRISM has been passively working with partners and stakeholders in the region to manage known infestations and prevent further spread. This includes funding herbicide treatments and dredging at two infested sites along Cayuga Lake beginning in 2019. More information can be found about the ongoing battle to control Hydrilla in Cayuga Lake in the interactive StoryMap below!




In 2017, the Finger Lakes Institute (FLI) at Hobart and William Smith Colleges (HWS) began our Hydrilla project, with the goal to survey for and control Hydrilla infestations in the Finger Lakes Region. Point-intercept surveys were conducted in waterbodies known to have Hydrilla populations, waterbodies nearby known populations, and areas around high-use boat launches in the region. Surveys will continue to target the recreational boating pathway of invasion, specifically boat launches and marinas. The Hydrilla project is possible thanks to the funding from the Environmental Protection Agency Great Lakes Restoration Initiative (EPA GLRI) grant and Finger Lakes – Lake Ontario Watershed Protection Alliance (FLLOWPA). An annual overview of previous seasons of the Hydrilla project can be found in the table below. For a detailed summary of plant surveys conducted in our search for new Hydrilla populations, check out the story map below!


2018 2019 2020 2021 2022
# Rake tosses 1,902 7,478 10,733 18,025 12,269
# Waterbodies sampled 2 16 15 13 12
# Counties sampled 3 11 13 11 10
Area surveyed (acres) ~107 shoreline miles 3,569 8,100 20,929 & ~50 shoreline miles 10,744

You can help monitor the spread of invasive species!

If you see a suspicious-looking plant, send photos and location to FLXplantID@gmail.com!

Additional Resources

Cayuga Lake Watershed Network

Cornell Cooperative Extension

Great Lakes Hydrilla Collaborative


Lansing Hydrilla Population Monitoring Summary 2021

Hydrilla WANTED poster 2020 (11×17) print 1

Hydrilla WANTED poster 2020 (11×17) print 2