Hydrilla in Cayuga Lake Inlet- Two Year Anniversary

by Kirsten Goranowski, FLI Watercraft Steward Program Assistant

Kirsten Goranowski, FLI Watercraft Steward Program Assistant
Kirsten Goranowski, FLI Watercraft Steward Program Assistant

This mid-August marks the two-year anniversary of the Hydrilla verticillata detection in the Cayuga Lake Inlet by a staff member of the Cayuga Lake Floating Classroom (Cornell Cooperative Extension Invasive Species Program, 2012). The Cayuga Lake Inlet is located between Treman State Marine Park and the Route 89 Bridge in Ithaca, New York.

For those of you who are are unfamiliar with Hydrilla verticillata, or commonly known as ‘hydrilla,’ this is an extremely aggressive aquatic invasive that is considered to be one of the world’s worst invasive species. In fact, infestations are capable of altering the physical and chemical characteristics of lakes, as it causes impacts such as producing in extremely thick mats that obstruct recreation, block sunlight for native plants, and decrease waterfowl feeding areas (Cornell Cooperative Extension Invasive Species Program, 2012). Figure 1 illustrates a close up look at this extremely hardy aquatic invasive plant that makes recreation in a waterbody nearly impossible once it has become established. Try swimming through that! Gross!

Figure 1: Taken from www.nyis.org. Close-up of Hydrilla. Photo: Chris Evans, River to River CWMA, Bugwood.org
Figure 1: Taken from http://www.nyis.org. Close-up of Hydrilla. Photo: Chris Evans, River to River CWMA, Bugwood.org

Native to Southeast Asia, hydrilla was first imported into the United States as an aquarium plant, which was later believed to have been released into the wild through an aquarium dump during the 1950’s in Florida (Cornell Cooperative Extension Invasive Species Program, 2012). Hydrilla has been listed as a noxious weed since 1979 on the USDA’s Federal Noxious Weed List and is illegal to sell/buy in the United States (Menninger, 2011).

Soon after its discovery in 2011, the Hydrilla Task Force formed to research the risks and possible responses of this invasive, involve agencies at all levels of government and interested parties, make recommendations to those that could carry out action, and to provide extensive outreach and education in the Cayuga Lake Watershed. A follow up survey in late August 2011 by aquatic biologist Robert Johnson found roughly 6-8 acres of dense hydrilla mats located in high boat traffic areas of the Cayuga Inlet (Menninger, 2011).

This location represented a concern for the potential of increasing the spread of Hydrilla due to recreational disturbance, as fragments are easily caught on boat propellers and further dispersed. In Fighting Hydrilla in Cayuga Inlet 2011, the City of Ithaca declared an emergency and the decision to use herbicides was not made lightly (Cornell Cooperative Extension Tompkins County). The Inlet remained closed for about two weeks to conduct the October 2011 herbicide application of Endothall, as well as reduce disturbance by boat traffic. Use of the Inlet for drinking water was restricted for 14 days within 600 feet of the application site. Endothall levels were continually monitored until they were undetectable by the Tompkins County Department of Health as well as the City of Ithaca.

With its first year, it was found that the Endothall application, which was applied 4 different times, killed approximately 95% of the plants biomass above the soil level (which is very good). This bought some time as the Hydrilla Task Force continued to meet throughout the winter months as they drafted an initial 2012 Hydrilla Work Plan. The 2011 herbicide proved to be successful, so they continued a reapplication of Endothall on June 26th, 2012. To increase the effectiveness of eradication in the second year, another herbicide known as Fluridone was applied from July 12th to October 31st in 2012 at very low levels. This additional herbicide assisted in hindering plant growth by killing the roots and tubers. Combined with these efforts, trained volunteers and professionals helped monitor the infestation for any new populations before, during and after these applications.

Figure 2: Invasion Curve (image from Southwest Montana Science Partnership's Module on Plants and Pollinators
Figure 2: Invasion Curve (image from Southwest Montana Science Partnership’s Module on Plants and Pollinators

When infestations such as these are analyzed for action, the Invasion Curve is used by organizations to determine the most sensible action. This Invasion Curve (Figure 2) illustrates introduction of an invasive plant, animal, or insect and its feasibility of eradication over time. As you can see, the longer an invasive species is established over time the eradication feasibility continues to decrease. Fortunately, this hydrilla infestation was detected early enough where eradication was still possible and feasible. There was no sign of Hydrilla in the south end of Cayuga Lake, as the infestation just reached to the mouth of the Inlet (Menninger, 2011).

This past July 16th 2013 was the first Endothall treatment of the 2013 season and was applied in the Cayuga Inlet, the Flood Control Channel, the Treman Marina, and the lower reaches of Cascadilla and Six Mile Creeks. After 24 hours they reopened the Cayuga Inlet on July 17th, 2013 at 8 am, and the first water quality results have since been published. The New York State Department of Environmental Conservation, Tompkins County Soil and Water Conservation District, Tompkins County Health Department, and the Ithaca Area Wastewater Treatment Facility will continue to work together in the Enthodall Water Quality Monitoring over the next few weeks. Be sure to sign up and receive hydrilla email updates if you are interested.

So, although this eradication is claimed to be still feasible, how much did this treatment cost you may ask? The Endothall treatment this year was contracted to cost $104,140, and the proposed herbicide Fluridone is contracted to cost between $234,267 and $309,109 according to James Balyszak, Program Manager of the Hydrilla Task Force. The expenses for the treatments will be covered by a mix of federal and state funding. He said that these estimated numbers are high due to the inlet’s flow that disperses the herbicide more quickly (Casler, 2013). However, left untreated the problem would cost even more.

So How Can You Help?
It is extremely important to become part of the solution by taking the necessary precautions in Cleaning, Draining, and Drying your boat! Also, properly dispose of water weeds away from the watershed on dry land to prevent fragments or seeds making their way back into the lake.

You should also become familiar with the characteristics of Hydrilla, and report Hydrilla suspects to the Cornell Cooperative Extension of Tompkins County, and to attend future Hydrilla events and volunteer opportunities!

Lastly, strike up a conversation with your local FLI Watercraft Steward! Visit Alex who is working this summer at Taughannock Falls State Park and Allen Treman Marine State Park boat launches to help stop the spread of aquatic invasive species such as Hydrilla!

Upcoming Hydrilla Trainings-
Aquatic Invasive Species Trainings:
The Cayuga County Department of Planning and Economic Development along with Watershed Assessment Associates, LLC and the Finger Lakes Institute will be holding five aquatic invasive species identification training workshops for the public across the Finger Lakes in July. These trainings are free, open to the public, watershed associations, watershed officials and agency personnel. Participants will learn how to identify invasive aquatic plants and animals through presentations and hands-on activities. They will also learn what to do if they find a species of concern. Details

  • July 22nd: 6 pm, Cayuga Lake Watershed Network Offices, 2nd Floor, Zabriskie Hall, Aurora
  • July 23rd: 1 pm, Cornell Cooperative Extension of Tompkins County, Meeting Room A, Ithaca
  • July 23rd: 6 pm, Finger Lakes Institute, Geneva
  • July 24th: 10 am, Yates County Office Building- Auditorium, Penn Yan
  • July 24th: 6 pm, First Presbyterian Church, Skaneateles

Hydrilla Hunt Webinar: On Friday, July 26 The Nature Conservancy (TNC) and the New York Federation of Lake Associations (NYSFOLA) will present a webinar to instruct volunteers on the skills needed to identify Hydrilla verticillata (hydrilla). The webinar will kick off the Hydrilla Hunt on Friday, July 26, at 2:00 pm. Participants can join the webinar. Sign in with your name and email.  The password is Hydri11a (using the number 1 not the letter l).

Works Cited
Casler, A. (2013, July 7). Problematic plant threatens lakes. Democrat and Chronicle , p. 1b & 7b.

Cornell Cooperative Extension Invasive Species Program. (2012, October 3). Hydrilla. Retrieved July 10, 2013, from The New York Invasive Species Clearinghouse: http://www.nyis.info/?action=invasive_detail&id=16

Cornell Cooperative Extension Tompkins County. (n.d.). Herbicides In Use. Retrieved from Cornell Cooperative Extension: http://ccetompkins.org/environment/invasive-species/herbicides-use

Menninger, H. (2011). Hydrilla verticillata in the Cayuga Inlet: A science-based review to guide management actions. NY Invasive Species Research Institute, Cornell University, 1-11. Ithaca, NY, USA. Retrieved from The New.

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