2011 Hydrilla Eradication Efforts

DISCOVERY OF HYDRILLA IN CAYUGA INLET

Hydrilla was first found on August 4th, 2011 in Linderman Creek. This first specimen was found by Jordan Stark, a volunteer on the Cayuga Lake Floating Classroom. Through careful surveying, hydrilla was also found in many other areas of Cayuga Inlet.

FIGHTING HYDRILLA IN CAYUGA INLET 2011

Prepared by the Hydrilla Task Force of the Cayuga Lake Watershed, in widespread consultation with others

The Cayuga Inlet was closed for about 2 weeks in mid-October 2011 to allow the use of the herbicide endothall to kill an extremely aggressive invasive plant, hydrilla, that threatens the ecosystem of the Great Lakes.  This action was recommended by the Hydrilla  Task Force, after consultation with local community members, businesses, politicians, and Inlet users.  Until the application of the herbicide, the City of Ithaca strongly discouraged the use of boats in the inlet.

It cost about $91,000 (plus staff time and volunteer time) to contain hydrilla this first year, and substantial investments will be needed for follow-up for the next 5 years or more to reach the goal of eradication.  Left unchecked, the cost to manage hydrilla will rise dramatically.  States with widespread hydrilla infestations, such as Florida, spend up to $30 million per year to contain hydrilla and allow for limited boat traffic.

Hydrilla Eradication Experience in US

Experience with hydrilla in California, Washington, Florida and elsewhere suggested we had a very narrow window of opportunity - a window of just a few weeks - to arrest hydrilla spread in the Cayuga Inlet in the fall of 2011.  The widespread formation of reproductive structures call turions would substantially increase the area of the infestation and increase the likeihood of the spread of hydrilla into the lake. With a quick response, the Hydrilla Task Force determined we had a good chance of wiping out hydrilla in the Cayuga Lake watershed, based on the successful eradication of hydrilla elsewhere in the US.

Summary of 2011 Actions

Local Task Force Debrief: Responding to hydrilla in the Cayuga Inlet supplies a summary of local successes and challenges to guide future response efforts, both local and state. (Yellow highlighted items were never addressed)

  1. The Hydrilla Task Force was formed to a) research the risks posed by hydrilla and the possible responses, b) involve agencies at all levels of government and other interested parties c) make recommendations to the entities that could carry out actions and d) do extensive outreach and education in the Cayuga Lake Watershed.
  2. The City of Ithaca strongly discouraged the use of boats of any kind  in the Inlet.  The City's paddle boat docks, the Farmers' Market dock and informal launches and the Treman Boat Launch were all closed.  
  3. The Hydrilla Task Force recommended that the quick-acting herbicide endothall (trade name Aquathol) be used in the inlet to stop or slow the growth of reproductive structures (called "turions").
  4. Tompkins County Soil & Water Conservation district applied for a DEC permit to apply the herbicide.  Formal notification of affected landowners occurred on September 14, 2011 meaning  October 6, 2011 was the first day the the permit could have been issued. 
  5. Because the potential ecological and  economic damage from hydrilla requires strong action, the City of Ithaca declared an emergency, which led to the Sheriff of Tompkins County (who has authority over waterways in the county) to close the Inlet for a period of time that included the window of herbicide applicaiton. 
  6. The herbicide was applied by a licensed and certified herbicide applicator, Allied Biological, with extensive experience in New York State. The amount of endothall  used in Cayuga Inlet was far lower than the concentrations that are toxic to humans and animals. As a precaution, use of the water in the Inlet for drinking (including by animals or residents of the "Jungle" area) was restricted for 14 days. The restrictions on water use applied within 600 feet of the site of application.  The Bolton Point water intake is three miles from the Inlet.  It was monitored carefully, even though it was considered well outside the affected area.  Some lake house owners do draw their water from the lake, and were notified; however, none of the lake houses are within 600 feet of the site of application, and all have access to municipal water lines.  Signs and other outreach notified dogwalkers, residents of the Jungle, and others of the restrictions.  There was a one-day restriction on swimming and bathing in Cayuga Inlet, as a safety precaution. 
  7. The Tompkins County Department of Health, in cooperation with the City of Ithaca, monitored endothall levels in the Cayuga Inlet after the herbicide was applied, again after 3 days, again after 7 days, and every 7 days after that until endothall levels were undetectable. Water monitoring results.
  8. The herbicided killed approximately 95% of the hydrilla biomass above the soil level, which is a very good result. The remain hydrilla had strong re-growth, probably in part due to the unusually warm fall. Plant monitoring results.
  9. Suction-assisted diver harvesting was tried and rejected as a useful management technique in this situation. It broke the hydrilla into fragments that were impossible to capture meaning it would spread the hydrilla, not stop it. 
  10. Water levels in Cayuga Lake were dropped earlier than usual, but not lower than the level usually achieved in March as dictated by the rule curve.  Water levels explained.
  11. The Hydrilla Task Force and its subgroups continued to meet through the winter in order to prepare a hydrilla work plan for 2012.

RESPONSES TO CONCERNS EXPRESSED BY THE COMMUNITY

  1. Wasn't it too late?  Didn't I read that the herbicide needed to be applied by September? While an earlier application might have been preferable, any reasonable effort to limit the spread of hydrilla is valuable.  Applying the herbicide in October killed off much of the exposed hydrilla plant material, providing a window of opportunity for planning other eradication efforts in 2012 and beyond.  Additionally, the high water events in September created turbid water and blocked some sunlight, slowing the growth of the plant.

  2. But hasn't plant material already spread into Cayuga Lake?  Hasn't hydrilla been around for a couple of years?  And this year, we've had huge flooding and waterflows through the Inlet in September. A careful investigation of the hydrilla plants by Robert Johnson, a former faculty member at Cornell's Department of Ecology and Evolutionary Biology and now with the consulting company Racine‐Johnson Aquatic Ecologists, and consultations with hydrilla experts around the country suggests that this is the first year of any significant hydrilla growth in Cayuga Inlet.  For more information about the infestation, see the "Science-based review to guide management" prepared by the New York Invasive Species Research Institute. Despite the heavy waterflows, ongoing observations during September suggest that hydrilla spread has been quite limited.  If pieces did break off and float into Cayuga Lake, the evidence is that the pieces flowed into deep water, where they cannot survive.  Prevailing winds and typical water patterns would have driven pieces back towards Stewart Park.  So far, no evidence of hydrilla has been found there or in Fall Creek. By closing the Inlet to boat traffic, the risk of breaking off pieces of hydrilla vegetation was dramatically reduced.  The NYS DEC has said that any efforts to control hydrilla, even if later than ideal, would still useful.

  3. What about all the boats that have been using the Inlet since August?  There is some risk that plant material has been moved out of the Inlet by boats or boat trailers.  Many boats and their trailers have received careful cleaning at stations established at Treman Marine Park and Johnson's Boatyard.  All boat owners are strongly encouraged to have their boats and trailers carefully checked before putting them back in the water in any location, especially other Finger Lakes.

  4. Why did it take so long to get the herbicide permit?  In other states, the herbicide might have been applied within days after the initial discovery in early August.  However, New York State laws and regulations established to safeguard state residents led to careful discussion among the NYS DEC, the City of Ithaca, Tompkins County, and local and national hydrilla experts to establish the best procedure.  That discussion led to the decision to have the Tompkins County Soil and Water Conservation District be the organization to request the herbicide permit from NYSDEC.  Once that decision was made, the formal notification of landowners/leaseholders and the full 21-day opportunity for responses (or earlier, if all landowners  respond prior to the end of 21 days) needed to happen before the herbicide could be applied.

  5. Who paid for this?  The NYS DEC will reimburse Tompkins County for about $50,000 of the cost of this application of the herbicide.  The Tompkins County Legislature has allocated about $26,000 from its reserves toward the cost.  The chemical company that provides endothall has kindly offered to contribute $15,000 towards the treatment.  All those funds covered the direct costs.  City of Ithaca, Tompkins County Soil & Water Conservation District, Cooperative Extension, and many volunteers from multiple organizations have contributed substantial staff time to planning and executing the hydrilla management plan.  The County and the City collaboratively made a request that NYS cover these costs as this is a State controlled water body.

  6. How did the inlet closing work?  Buoys were placed at the mouth of the Inlet during the first week of October.  The Tompkins County sheriff patrolled the Inlet.  The U.S. Coast Guard issued a notice to marines that the Inlet is closed.  No boat traffic at all was allowed.

    • The closing extended from the Route 79 bridge (Buffalo Street Bridge) north to the mouth of the Inlet (see map ).The Inlet was closed for 14 days to ensure that the herbicide had sufficient time to affect the exposed hydrilla. 
    • Sections of the Inlet south of the Rt. 79 bridge remained closed after the herbicide treatment.  Infestations of hydrilla were discovered after the DEC permit application was submitted.  These areas were treated using diver assisted suction harvesting. 
  7. What happened next? After the initial herbicide application to knock back hydrilla, the Hydrilla Task Force of the Cayuga Lake Watershed used the winter to conduct a careful analysis of possible actions.  Use of the same or different herbicides in 2012, physical suctioning up of hydrilla roots, and other actions were all considered.  The Inlet will most likely be closed again for short periods of time in 2012 for further treatment.

HOW CAN I LEARN MORE?

Last Updated: September 16, 2013

Last updated: September 16th 2013 - 11:20pm