Milfoil Control
CLAPA’s ongoing efforts in monitoring, diver harvesting, and occasional chemical treatment are critical to controlling the spread of the invasive species variable milfoil.
You can help reduce invasives in our lake. If you see milfoil, please report its location ASAP via email to clapalake@gmail.com. Milfoil float markers to mark sightings will be available for members and the public at the boat ramp during Lake Host hours or pick-up can be arranged via email: mark@quabbininc.com or 978-257-1865.
2026 Treatment and Plans
November 2025 – An aquatic plant mitigation request for bids was sent to four dive companies. Twin State Divers (same dive company used in 2025) was the low bidder
December 2025 - CLAPA received a 2026 Exotic Aquatic Plant Control matching grant from NHDES. The total grant award of $7,360.00 covers 50% of the milfoil abatement cost for up to 12 days of DASH (Diver-Assisted Suction Harvesting) or SCUBA diver hand harvesting. Twin State Expedited Dive Services, LLC, was chosen to perform the milfoil harvesting services.
Early June 2026 – NHDES Survey of Contoocook Lake identified three areas with only minimal milfoil present: on both sides coming out of Jowders Cove and the cove near the Woodbound Inn’s cabins. The ProcellaCOR herbicide treatment that was applied in 2025 resulted in slow growth of variable milfoil in our lake, therefore less than the awarded amount of diver harvesting will be needed.
Late June 2026 - Twin State Divers provided 4 man-days of diving. A total of less than 1 bag (< 18 gallons) of variable milfoil was removed from the lake). The divers finished early on the second day, so we had them swim the perimeter of last year’s treated area looking for additional variable milfoil colonies. Only a few plants were located. The cost for diver harvesting was $4,620.00; NHDES paid 50% of the cost.
July 2026 – NHDES Survey of Contoocook Lake identified only one area with minimal milfoil present (to the left of Jowders Cove).
Late August 2026 - Twin State Divers will provide 1 additional man-day of diving to remove the variable milfoil located by NHDES during their July survey. Since we will be charged for a day of diving, our plan is to have the divers check additional areas around the lake with any remaining time. Estimated cost for diver harvesting, $1,350; NHDES will pay 50% of the cost.
2025 Treatment and Results
Due to high concentrations of milfoil in several areas, in 2025 CLAPA contracted Solitude Lake Management to apply a Procellacor herbicide treatment in the areas indicated on the map below. Cost of this treatment was offset by 50% matching funds from NH DES, and a generous $1000 donation from Jaffrey Conservation Commission, for which we are grateful.
The treatment was very successful. As noted in the follow-up survey report below, “No viable milfoil was seen in or adjacent to the treatment areas during the survey”. Only one day of additional diver harvesting was needed in the untreated areas.
What You Can Do!
Help reduce invasives in our lake. If you see milfoil, please report its location ASAP via email to clapalake@gmail.com. Milfoil float markers to mark sightings will be available for members and the public at the boat ramp during Lake Host hours or pick-up can be arranged via email: mark@quabbininc.com or 978-257-1865.
