Volunteers Community Partners


Project: Hydrilla verticillata control in New York’s Great Lakes Basin
Years: 2017 – 2019, no-cost time extension through 03/2021
Funded By: Environmental Protection Agency Great Lakes Restoration Initiative, $598,960.00
Project Manager: Kate Des Jardin, desjardin@hws.edu

Hydrilla is an invasive aquatic plant threatening to invade our pristine Finger Lakes waterways.

The Finger Lakes Institute and Finger Lakes PRISM are asking everyone who lives or recreates on Cayuga Lake to be on the lookout for Hydrilla.


  • Choking native aquatic species
  • Hitchhiking unauthorized on boats
  • Obstructing swimming and fishing
  • Hijacking the local economy


  • Elongated stem
  • Small, blade-shaped leaves with toothy edges
  • Whorls of 5 leaves along the stem
  • Grows an inch per day up to 30 feet in length
  • Last seen in Cayuga Lake

Figure 1. Hydrilla sample. Note the toothed leaves in whorls of five.

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 of the Great Lakes basin. Hydrilla is a perennial plant with noticeably toothed leaves that often grow in whorls of three to eight, usually five. Hydrilla spreads quickly and grows in dense stands that out-compete native species and negatively affect the aquatic ecosystem. Hydrilla can clog waterways, restrict water flow, 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.

Hydrilla is very difficult to detect in low abundance and closely resembles native Elodea spp., which is prevalent in New York State (NYS) and Great Lake waterways.

Hydrilla has been reported previously in the Great Lakes basin of NY in Erie, Monroe, Niagara, and Tompkins Counties (http://www.dec.ny.gov/animals/104790.html). The infestation at the south end of Cayuga Lake, which is connected hydrologically to Lake Ontario, has been the focus of significant state and federally funded rapid response efforts to control the spread and eradicate the population of Hydrilla since 2011. Unfortunately, in October 2016, a Hydrilla infestation approximately 30 acres in size was found 35 km north of the previously/currently managed infestation offshore in the nearshore areas, close to Aurora in Cayuga County. The Village of Aurora uses Cayuga Lake as a drinking water supply, which disqualifies traditional chemical controls that have been successful in other treatments across the state. Treatment and monitoring has been conducted by the United State Army Corp of Engineers (USACE) in collaboration with local stakeholders and partners.

Survey and Control

In 2017, the Finger Lakes Institute (FLI) at Hobart and William Smith Colleges (HWS) was awarded an Environmental Protection Agency Great Lakes Restoration Initiative (EPA GLRI) grant to survey for and control Hydrilla infestations. Point-intercept surveys were conducted in waterbodies known to have Hydrilla populations, waterbodies nearby known infestations, and areas around high-use boat launches in the Finger Lakes region and in Lake Ontario embayments. A no-cost time extension has been granted for this project, which allows survey and control to occur during the 2020 field season. Surveys will continue to target the recreational boating pathway of invasion, specifically boat launches and marinas.

2018 Survey and Control

In the fall of 2018, point intercept surveys were conducted around the entirety of Cayuga Lake. One Hydrilla infestation was discovered at a private marina in King Ferry. This site was dredged in March 2019 to remove Hydrilla tubers from the sediment. In the event that some of the tubers remained, the site was monitored for Hydrilla regrowth. Hydrilla did begin to regrow at the end of June 2019 and treatment was coordinated with the USACE. A spot treatment using endothall was conducted in August 2019. Monitoring will continue at this site for the 2020 field season, with a spot treatment conducted by the USACE as needed.

Figure 2. Map of 2018 survey

2019 Survey and Control

During the 2019 field season, point-intercept surveys targeted boat launches and marinas in waterbodies known to have Hydrilla populations, waterbodies nearby known infestations, and areas around high-use boat launches in the Finger Lakes region and in Lake Ontario embayments. Rake tosses were done at regular intervals within a one-mile radius of marinas and boat launches, to water depths of 25 ft. A new infestation was detected at a private marina at the end of August 2019. This site was treated using a copper-based herbicide in October 2019. For the 2020 field season, this site will be further monitored and treated using the herbicide fluridone.

Figure 3. Map of sites surveyed in 2019. Sites with Hydrilla are indicated in red.

Education and Outreach

Throughout the course of the project, community outreach efforts have been made to raise awareness on the negative effects of Hydrilla and other aquatic invasive species.  These efforts include workshops, presentations and posters, and tabling at several events, such as the CNY Boat Show, Gardenscape of Rochester, the New York State Fair, and conservation field days.

Figure 4. AIS workshop held at the Finger Lakes Institute.


Several partners have also committed to provide training, outreach, and communication to the community, including The Montezuma Audubon Center, Cayuga Lake Watershed Network, and the New York State Federation of Lake Associations.

Information on the high priority invasive species of the Finger Lakes region can be found in our invasive species field guide and fact sheets. Profiles and distribution maps of aquatic and terrestrial invasive species are designed to assist the public in identifying and managing invasive species.

Field Guide

Fact Sheets

You can help monitor the spread of invasive species!

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

Zip bag kits are available upon request.

FLI PRISM Hydrilla card

You can also become a member of the Finger Lakes Institute’s Plant Detectors!

This initiative is focused on getting the community involved in identifying and reporting high priority invasive species, including Hydrilla, water chestnut (Trapa natans), and starry stonewort (Nitellopsis obtusa), across the Finger Lakes region. Additional information can be found at: http://fingerlakesinvasives.org/macrophyte-survey-program/