Parts of the Cayuga Inlet will be reopened to boat traffic and recreational use this afternoon after the City of Ithaca announced the successful application of herbicide to combat the presence of hydrilla.
In a written statement, Tompkins County Sheriff Kenneth Lansing said portions of the inlet will be re-opened at 3 p.m. today, but the area between the Route 79 Bridge and the fish ladder will remain closed until further notice.
Hydrilla verticillata, an invasive aquatic species, was found in the Cayuga Inlet, Cascadilla Creek and Linderman Creek in August. The City asked boaters to stop using the inlet area Sept. 19.
The Cayuga Inlet Hydrilla Task Force, created in August to address the infestation, advised use of the herbicide in early October, and City of Ithaca Mayor Carolyn Peterson declared an environmental emergency Oct. 5. In the release, she asked Lansing to close the inlet until further notice due to the hydrilla’s presence.
Allied Biological, a lake management consulting company based in the Northeast, administered Herbicide Aquathol K to prevent the plant’s spread through reproduction Oct. 11 and 12, Julie Holcomb, City of Ithaca public information officer, said.
Holcomb said the company spread the herbicide over the 95-acre infected area using GPS units and airboats, flat-bottomed vessels with large, aircraft-like propellers, which sprayed the herbicide about two feet under water.
Holcomb said the inlet remained close for 48 hours to leave the water undisturbed, and the City will soon sample the plant to gauge how it has reacted to the chemical.
She said the herbicide will not eradicate the plant, but rather only the green vegetative part of the plant. She said the City expects the presence of hydrilla next year and is preparing a long-term plan to completely destroy the tubers, which are underground and connected to the roots of the plant.
“That was the purpose of this emergency treatment — to contain and knock back the plant a little bit,” she said. “We knew we couldn’t kill it all with one treatment application.”
Holcomb said the City discovered the presence of hydrilla between the Route 79 Bridge and the Fish Ladder after officials applied for the herbicide permit on Sept. 14. However, Holcomb said that, due to time and budgetary constraints, the City could not immediately address hydrilla’s presence in the area.
“We had a very short window of operation to pull this off on before the plant started reproducing,” Holcomb said.
Holcomb said City workers will examine the presence of hydrilla and its density in the remaining portion of the inlet throughout the course of the next week. Although the herbicide is not toxic to humans or animals, but she urged community members to not use the freshwater for domestic use over the next two weeks. The Tompkins County Department of Health is monitoring the water quality, she said.
If left unaddressed, Holcomb said, existing hydrilla plants could reproduce and their presence would increase exponentially, potentially threatening regional waterways — from the Cayuga Lake to the Great Lakes system.
She said the City originally estimated application of the herbicide would cost about $100,000. To fund the project, the New York State Department of Environmental Conservation offered $50,000, the Tompkins County legislature approved $26,100 in funding, and the City of Ithaca paid for some staff and public awareness costs. The herbicide’s manufacturer also contributed $15,000 in product. The estimates were calculated before hydrilla was spotted between the Route 79 Bridge and the Fish Ladder.
In a written statement, Peterson thanked businesses, local agencies and recreational users of the inlet for their cooperation in the herbicide’s application.
“This is a situation that no municipality wants to find itself in, but the dedication and the commitment of the community to save our waterways has been tremendous,” she said. “We are already beginning to plan for the next phase of treatment.”
