Hydrilla, an invasive aquatic weed, has been overtaking the Croton River and has the potential of spreading into the Hudson. It clogs boat motors, reduces oxygen levels, and chokes local plants. A survey was conducted last summer by the DEC and Allied Biological and found that hydrilla has not yet spread into the Hudson, but that it has increased in volume in the Croton River.
The DEC has proposed a hydrilla eradication plan for this summer, and will be collaborating with other environmental groups and stakeholders. They have elected to use aquatic herbicide endothall in the Croton River, a chemical that has already been successfully used to remove hydrilla in other waterways. It will be released in controlled amounts on a 1.2 mile stretch of the river, as to avoid contamination of Croton drinking water and of the river itself.
The treatment will likely be scheduled in mid-August, and will impose various restrictions on the river. The water use restrictions are what make me the most concerned about this proposed plan. Swimming, fishing, and boating will likely be banned for 2-3 days, and on the day prior to the treatment, a neon pink dye will be used in the river. This dye is apparently non toxic, so no restrictions will be enforced on river users… but the river will be bright pink.
The DEC has done this treatment before. They have all the correct permits and have done the research and are following the rules they are supposed to adhere to. I have read their research and plans, and I have looked into past hydrilla removal projects, and it all seems to check out.
I cannot help but be concerned about this treatment. How is it safe to release a herbicide into the river? In all of the articles I’ve read on endothall, I have found that the herbicide is effective in removing hydrilla, but it is also effective in killing other plant life. By releasing 
the herbicide into the Croton River, the chemical could potentially get into plants, animals, and therefore, us. The fact that a water use ban is in place for a time following the treatment seems to prove that endothall is harmful.Additionally, the half-life (half time it takes for the active ingredient to become inactive) of endothall is 7 days; therefore, it should take 2 weeks for the chemical to break down. Despite this fact, the water use restrictions are only going to be in place for 2-3 days.
I am not convinced that this method of treating the hydrilla problem in the Croton River is going to be safe or effective, and am concerned that the endothall could be harmful to aquatic life. This treatment is also likely to affect the Hudson River, because the Croton River is one of the Hudson’s tributaries.With the Croton River treatment only about 2 weeks away, and very little information out for the public about the DEC’s plan, I hope to find more reassurance about the use of endothall.
I will give updates as I learn more!
You can learn more by following these links:
2015 Journal News Article: “Hydrilla invades Hudson estuary”
Journal News – 2016 Swimming Ban Announced
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