Update on Herbicide Treatment for Eurasian Watermilfoil

UPDATE #3 (29 June): ProcellaCOR Treatment Successfully Completed – What to Expect: The firm of Ready-Scout was at Chateaugay Lake on Friday, June 28, to carry out the ProcellaCOR EC herbicide treatment of the Narrows from just south of the Sand Bar to the Narrows bridge. Conditions were favorable, with clear sunny weather and little wind. The treatment was started early in the morning and proceeded from south to north, finishing by 2:15 pm. There was minimal boat traffic, and most had gotten the message to avoid the area during application, so as not to create waves that would displace the herbicide.

The herbicide is applied underwater through injection hoses from a tank where it has been mixed with water to the right concentration. See the photo of the air boat rig. The Eurasian watermilfoil absorbs the herbicide, which mimics a plant hormone that stimulates rapid growth. This causes the stems to elongate, and the plant collapses and dies back.
The milfoil die-off will be occurring over two or three weeks and is similar to the end-of-season die-off that occurs naturally each year. The treatment takes place early in the growing season to reduce the amount of biomass and also minimize the impact on other aquatic plants, which tend to emerge later than Eurasian watermilfoil. Native plants that are somewhat susceptible, such as water lilies and coontail, may show some browning and stem curl, but typically recover.

Over the next few weeks there may be some plant wash-up. If you collect the wash-up, it should not be composted as it may have herbicide residues. The wash-up can be collected and disposed of with regular household trash or burned in a campfire.

Water samples will be collected over the next week and sent to a lab for analysis, to document when the concentration has dropped from the application concentration of 6 parts per billion (ppb) to 1 ppb. At that point, restrictions on using the treated water to irrigate broad-leaf plants (dicots), such as shrubs and flowers, will be lifted. We will send out an email notification and post to Facebook. In the meantime, it is OK to use the treated water to irrigate grass (a monocot plant that is not affected by ProcellaCOR). There are no restrictions on swimming, fishing, bathing, dishwashing or even drinking treated water, as ProcellaCOR’s mode of action is specific to plants and will not impact animals including humans.
At the end of the summer, the applicator will return to survey the results and there will be an aquatic plant survey to compare conditions pre- and post-treatment.

UPDATE #2 (24 June):  We received final approval of our Notice of Intent.  After consulting with our Certified Lake Manager and based on the approved Notice of Intent, application of ProcellaCOR EC will occur on Friday, 28 June, when the weather will be better.  Boats should avoid the treatment area during application which will take place from 7:00 am to 5:00 pm.  Thank you for your flexibility as we have worked through these complicated regulatory processes.  As a reminder, there is a link to a map of the treatment areas in the original blog post below.

UPDATE #1 (22 June):  Our permit to use the herbicide ProcellaCOR EC was approved by the APA on Thursday evening.  We immediately filed our notice of intent to proceed and will receive additional information early next week.  We are aiming for a mid-week application (Wednesday, 26 June or Thursday, 27 June), but weather and final approval to proceed could push application a day or two to the right.  Application must occur by 30 June at the latest, per our APA permit.  We will continue to provide updates on our Facebook page and website.  

Friends of Chateaugay Lake,

The Chateaugay Lake Foundation’s application to use the herbicide, ProcellaCOR EC, to treat Eurasian watermilfoil in the upper Narrows will be considered at the Adirondack Park Agency’s Board meeting on Thursday, June 20th.  If our application is approved, the treatment will take place the following Wednesday, June 26th. The treatment needs to occur within the window approved by the NYS Department of Environmental Conservation (DEC), which runs through July 2. We want to have the treatment accomplished before the busy July 4th holiday period.
Because of the short lead-time, we are giving people a heads-up about what to expect, assuming treatment is approved.

–The treatment area where the herbicide will be applied extends from just south of the Sand Bar to the Narrows Bridge. The dilution zone extends from north of the bridge through the Narrows and the Lower Lake inlet area. A map showing these areas can be viewed here

–The expected date of treatment is Wednesday, June 26th. Severe weather conditions might necessitate rescheduling. 

–The treatment will take about 4 hours to complete, starting in the morning between 8:00 and 9:00 am and going until about 1:00 pm. No one should enter the treatment area until the application is complete. Boaters should avoid the area for several hours after treatment, or else travel slowly, to avoid pushing water and redirecting the herbicide. Similarly, people should avoid running motors such as pump intakes to give the herbicide more time to be absorbed.

–Following treatment, there are no restrictions on water use for swimming, bathing, or dish washing. The application rate of the herbicide (about 7 ppb or parts per billion) is well below the threshold for drinking water (50 ppb).

–The main restrictions are on use of the treated water for irrigation of broad-leaved plants or irrigation for livestock. It is OK to use treated water to irrigate grass (monocot), but not other types of ornamental plants and shrubs (dicots like milfoil), until the residue level has declined to 1 ppb. It usually takes about a week to get confirmation from the lab that the restriction can be lifted. We will be sending out an email when that happens and also removing the treatment notice signs posted at public access points. (The restriction on watering livestock is because the residue might pass through to the manure used to compost plants.)

–Following treatment, floating milfoil and wash-up should be disposed of by means other than composting, for about a month. Alternatives would be to burn it as part of summer campfires or dispose of it as part of your normal household trash. 

Upon APA approval, we will be going out immediately with a postcard to shoreline property owners and lake businesses to confirm treatment is proceeding. We will also send out another email blast and post on Facebook. Inquiries can be directed to info@chateaugaylakefoundation.org or by calling 518-735-4385.
We appreciate your taking note of this important information and sharing it with your friends, neighbors and visitors, so our treatment program has the best chance of success!

Thank you for your continued support as we fight for our beautiful lake!

The Chateaugay Lake Foundation Board

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