DEC: Croton River hydrilla on the decline

Michael P. McKinney
Rockland/Westchester Journal News

CROTON-ON-HUDSON - After eight weeks of battling it with an herbicide, the invasive plant hydrilla in the Croton River is “showing noticeable signs of damage and decline as expected,” a state Department of Environmental Conservation spokeswoman said this week.

Samantha Epstein, the invasive species program coordinator with Clearwater, holds the invasive hydrilla she pulled from under the Croton River at the Black Rock Park in Croton, Aug. 27, 2015.

Treatment will continue until about mid-October, DEC spokeswoman Lori Severino said. After that, a survey of plants in the river will be undertaken.

Swimming, drinking and boating were not curtailed or otherwise affected by the treatment, which the DEC put forward to curb the green invasive plant that can seize control over water habitats and expand in thick mats that run afoul of boat engines.

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This year's treatment began July 5, andofficials should get a better sense from the state this fall of what effect this first summer of herbicide treatments had, Village Manager Janine King said. The DEC has also done a fewdrone surveys of the area.

King said she has not yet seen official data on the effectiveness of the herbicide fluridone against hydrilla in the river, though she’s heard anecdotally from some residents “who think the water looks better.”

Mayor Greg Schmidt said the summer was a kind of a trial year to see how things went, and part of what the state will examine are things it may need to tweak for next year.

"So far, I think it's been going well," Schmidt said. "I think the public understands the need for this because the hydrilla is really choking out the river."

The DEC has planned to make this the first of five years of the treatment. The project, which includes treatment, water sample analysis and monitoring of aquatic plants, is expected to cost $8.6 million over the five years and will be paid for by the state Environmental Protection Fund, Severino said.

Small amounts of the herbicide, which the state said were not harmful to people, have been used at two points in the river: the base of the Croton Dam and by Black Rock Park.

An aquatic plant survey, done last year, found that hydrilla became denser "and more abundant in the upper portion of the river, particularly around Black Rock Park, Silver Lake Beach and Paradise Island," according to the DEC's proposed plan for 2017.

The agency has collected regular samples from village wells during the treatment project, with water analysis reports posted on the DEC's website.

Herbicide levels detected in the sampling are "nowhere near rising to any level of any kind of health concern," King said.

In this 2015 file photo, hydrilla can be seen under the Croton River at the Black Rock Park in Croton.

Hydrilla was discovered in the Croton River in October 2013 and then detected the following year in Croton Bay during a site survey. According to the DEC, hydrilla's spread threatens the Hudson River's habitats and tributaries.

Last summer, the DEC proposed dealing with hydrilla using another herbicide, called endothall, which would have meant closing the river to swimming and other activities for a period. That option never went forward because, according to the state, water was flowing from the Croton Dam into the river at a rate above what would have allowed that herbicide to work.

The DEC is scheduled to hold a January public meeting in the village about hydrilla.