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Hopkinton Lake Milfoil Treatment to Temporarily Close Elm Brook Park Beach & Area Boat Ramps

Published July 8, 2014

HOPKINTON, N.H. – The U.S. Army Corps of Engineers will temporarily close the swimming beach at Elm Brook Park on Monday, July 14th and Tuesday, July 15th while portions of Hopkinton Lake are treated for the invasive variable milfoil plant.  The Stumpfield Road Boat Launch off Route 202/9 in Hopkinton will only be closed on Monday, July 14th.


During this time period, Elm Brook Park will continue to remain open to the public (weekday hours of 9 a.m. to 6 p.m.).  However, since swimming will be prohibited, user fees will not be charged for entry into the park.  Group picnic shelter reservations will still be accepted at normal fees. 


Variable milfoil is an invasive plant species that displaces native aquatic plants that provide food, shelter, and habitat for animals, fish, waterfowl, birds, and insects.  If left untreated, milfoil will destroy the lake habitat and many of the wildlife species that depend on it will perish.


A chemical herbicide named Navigate (2,4-D BEE), EPA Reg. No. 228-378-8959 and also State of New Hampshire approved, will be used to treat the variable milfoil.  2,4-D has a short half-life and does not bioaccumulate in the aquatic environment.  It is a systemic growth regulator that injures new growth and kills the leaves, stem, and roots.  It forces new growth to accelerate causing the plant cells to rupture, thus killing the plant. 

Variable milfoil treatment must take place during the growing season at normal lake levels.  Since Hopkinton Lakes is part of a flood control project that stores water every spring, the timeframe for treatment is limited. 


For additional information concerning the Hopkinton Lake variable milfoil treatment or the temporary beach and boat ramp closures, contact the project office at 603-746-3601.    

Steve Dermody

Release no. 2014-087