Hydrilla: Information & Cayuga Lake Management
Hydrilla (Hydrilla verticillata) is a highly invasive aquatic plant, first discovered at the south end of Cayuga Lake in 2011. Hydrilla grows quickly to fill and clog water up to 30 feet deep.
A team of educational, research, and public agencies work together to monitor for Hydrilla in our lake. Where hydrilla has been identified in Cayuga Lake, it is managed according to the Cayuga Lake Hydrilla Management Plan 2021-26, which includes targeted treatments with two herbicides (fluridone and chelated copper) by the US Army Corps of Engineers, the NYS DEC, and the FL-PRISM. Local activities are coordinated by the City of Ithaca, Departments of Health and Soil & Water Conservation Districts for Cayuga, Tompkins, and Seneca Counties. The Cayuga Lake Watershed Network supports public outreach, information sharing, and engagement around the lake.
This Story Map by the Finger Lakes PRISM provides an overview of Hydrilla in our lake.
What can you do?
Learn – The information on this webpage is updated annually.
Report – Take a photo of suspected Hydrilla, save the sample in secure baggie, and note location as exactly as possible and submit a report
Volunteer – To volunteer as a lakeshore and shallow water monitor for Hydrilla on Cayuga Lake, contact the
2025 Agency Reports
2025 NYS DEC / Water Resources Institute Region 7 Aquatic Invasive Species Program Annual Report
2025 End-of-Season Hydrilla Conference Session
Watch the session on YouTube
Catherine Farrell, Finger Lakes PRISM, Finger Lakes Institute: 2025 Overview of Hydrilla verticillata in Cayuga Lake
Richard Ruby and Michael Voorhees, US Army Corps of Engineers: 2025 Cayuga Lake, Aurora and Ithaca, NY Hydrilla Control Demonstration Project
Emily Timkey-Benzinger, NYS DEC: Cayuga Lake Hydrilla Control 2025 Updates
2025 Cayuga Lake Hydrilla treatment information
Hydrilla is currently actively managed in 6 sites across Cayuga Lake. Two sites, one in the “Northern Aurora Area” and another in the “Cayuga Lake Inlet Area” are managed by US Army Corps of Engineers (USACE) as part of the Cayuga Lake Hydrilla Control Demonstration Project (see brochures below). The management in the remaining three sites is overseen by the NYS DEC Regional Aquatic Invasive Species (AIS) Coordinator and the DEC Invasive Species Control Section. These sites include the South Aurora Area and Long Point State Park Area in Aurora, NY, Ladoga Bay in Lansing, NY, and the Sheldrake Area in Ovid, NY.
2025 US Army Corps of Engineers Aurora NY Area Hydrilla Control Demonstration Project Brochure
2025, June 2nd, Cayuga County Health Department Hydrilla Treatment Press Release
The Cayuga County Health Department will conduct water quality monitoring of the public
drinking water during this treatment period. The 2025 sampling results will be posted on the
Cayuga County Health Department website when they become available. Reports reviewing the
effectiveness of the hydrilla treatment in this part of Cayuga Lake can also be found on the Health
Department website.
2025 US Army Corps of Engineers Ithaca NY Area Hydrilla Control Demonstration Project Brochure
During the treatment season, Tompkins County Whole Health posts the in-Lake Water Results for Fluridone collected in the south end of Cayuga Lake. The sampling map and results are posted online when they become available : Water Quality Monitoring (Sampling) Results for Fluridone.
2025 NYSDEC Hydrilla treatment information. Questions for the DEC about hydrilla and its treatment in Cayuga Lake can be directed to the Region 7 Office by email: r7AIS@dec.ny.gov or phone: (607) 753- 3095x 258
2024 Cayuga Lake Hydrilla treatment information
2024, June 21 Cayuga County Health Department Hydrilla Press Relesase
2024 Ithaca Area Water Sampling Locations, USACE
2024 Water Quality Monitoring (Sampling) Results for Fluridone
2024 US Army Corps of Engineers Ithaca NY Area Hydrilla Control Demonstration Project Brochure
2024 US Army Corps of Engineers Aurora NY Area Hydrilla Control Demonstration Project Brochure
2024 End-of-Season Hydrilla Conference Session
Watch the full session on YouTube, and watch the Q&A session
Roxy Johnston: Hydrilla Backstory
Sam Beck-Andersen, Finger lakes Institute: Overview of Hydrilla verticillata in Cayuga Lake
Richard Ruby and Michael Voorhees, US Army Corps of Engineers: Cayuga Lake, Aurora and Ithaca, NY Hydrilla Control Demonstration Project
Emily Timkey-Benzinger, NYS DEC : NYSDEC Updates — Hydrilla Management in Cayuga Lake
2023 Cayuga Lake Hydrilla treatment and/or monitoring areas
City & Town of Ithaca (2011 – 2023): South end of the lake at Fall Creek and Cayuga Inlet, Southeast shore
Town of Lansing (2019-23): Finger Lakes Marina
Town of Genoa (2018-23): Don’s Marina
Village of Aurora (2017-23): Wells College dock & Aurora village waterfront.
Town of Ledyard (2023): Areas North of Aurora to Great Gully Cove, areas south to Long Point State Park
Town of Ovid (2023): Areas between Sheldrake Point to Wyers Point
2023, June 23rd Cayuga County Health Department Hydrilla Press Release
2023 US Army Corps of Engineers Aurora NY Hydrilla Control Demonstration Project Brochure
2023, June 27th Tompkins Co. Hydrilla Task Force Press Release
2023 Ithaca Area Treatment Maps
2023 US Army Corps of Engineers Ithaca NY Area Hydrilla Control Demonstration Project Brochure
2023, Early June Hydrilla Blog Post with Q&A
2023 June 8th Cayuga Lake Hydrilla Task Force Public Information Session
2023 Finger Lakes PRISM – Hydrilla Program Overview and Update Slides
2023 US-Army Corps of Engineers: Cayuga Lake, Ithaca and Aurora Hydrilla Update Slides
2023 NY DEC Cayuga Lake Hydrilla Treatment and Survey Plan Slides
2023 End-of-Season Hydrilla Updates Public Session (virtual)
Watch the full session on YouTube
12/18/23 Finger Lakes Institute, Finger Lakes PRISM, Overview of hydrilla in Cayuga Lake slides
12/18/23 NYS DEC Hydrilla Management on Cayuga Lake slides
Information about herbicides, monitoring, health and safety:
Cayuga County Health Department archive of Press Releases about Fluridone treatment and monitoring
Tompkins County Health Department Herbicide Monitoring and Results
More Information about hydrilla and its management:
Great Lakes Hydrilla Collaborative
Tompkins County Cooperative Extension Archive
This website is updated annually, below you will find information to links from past years
2022 updates on monitoring and treatment
Cayuga Lake Watershed Network End-of-Season Hydrilla Panel Presentations
2022 Finger Lakes PRISM Field Season Update
2022 ESF-NYS OPRHP Cayuga Lake Watercraft Inspection Stewards Update
2022 NYS DEC Cayuga Lake Hydrilla Project Summary and Forecast
Other 2022 Documents
CLWN Press Release re Hydrilla Monitoring and Treatment on Cayuga Lake’s South End, June 15, 2022
Lake Water Sampling Locations and Results for Fluridone concentrations, Ithaca NY, 2022
Cayuga County Health Department Press Release for Wells College Bay, June 24, 2022
Cayuga Lake at Stewart Park 2022 Hydrilla Control Demonstration Project Brochure
Cayuga Lake at Aurora 2022 Hydrilla Control Demonstration Project Brochure
Aurora NY 2022 Treatment Area Water Sampling Results
For older records about Cayuga Lake’s hydrilla situation:
Check out “Network News,” quarterly newsletter of CLWN, which published 1-2 articles each year about the hydrilla situation on Cayuga Lake. Especially note 2019 issues 2,3,4 and 2020 issues 2,3.
Since 2020, we have recorded our Zoom based community conference sessions which provide updated reports on hydrilla in Cayuga Lake from the experts. View these sessions on our YouTube Channel Aquatic Invasive Species playlist.
