Invasive Aquatic Plant Management
 Milfoil
In New Hampshire the most problematic invasive aquatic plant is invasive variable milfoil (Myriophyllum heterophyllum). This plant has infested over 50 waterbodies in New Hampshire. This species is not native to the waters of New Hampshire and therefore our ecosystem is not adapted to its presence. When it enters a waterbody it quickly reproduces replacing native vegetation. This vegetative replacement alters the ecosystem negatively affecting water quality and threatening ecosystem biodiversity.
What does variable milfoil look like?
Variable milfoil is a submerged aquatic plant characterized by feathery leaflets surrounding a thick, reddish main stem. Milfoil prefers to grow in relatively calm and shallow (less than 20 feet) waters. Fragments that break off the plant and grow roots are the primary form of reproduction and spreading. Boats, wind, current, and waterfowl transport these fragments. Identification of invasive (variable) milfoil versus the 5 native, noninvasive species can be difficult and must be performed by an aquatic biologist
How and when did it get in the Squam Lakes?
No one knows exactly how it got here or when it arrived. In mid-July 2000, the NHDES confirmed the presence of variable milfoil in the Squam River below the dam in Ashland. It has subsequently been found in many parts of Little Squam Lake, the Squam River, the Squam Channel, and some isolated sections of Big Squam.
 What can I do to help with the milfoil infestation?
•Volunteer to be a Weed Watcher. Volunteers are needed on Big and Little Squam Lakes. If interested, please call SLA at (603) 968-7336.
• Become a cove coordinator and organize your neighbors to survey your cove on a regular basis. SLA staff can come out and help train your cove’s volunteers.
• Join the Squam WeedWatchers Yahoo Newsgroup. Keep up to date on local milfoil news by joining this specific newsgroup.
• Familiarize yourself with invasive milfoil and what it looks like. Please see links below for more information.
• Notify SLA of any suspected new infestation sites. Bring a specimen to SLA by wrapping it in a wet paper towel, placing it in a labeled Ziploc bag. Please leave your name and phone number so we can let you know the plant’s identification or if we have further questions.
• Frequently inspect your boat by tipping up your engine or outdrive and remove any fragments. Please inspect after passing through an area with infestation, such as the Squam Channel. Don't prop wash fragments off. You'll create many new plants!
• Dispose of any fragments or plants in your household trash.
Where is exotic milfoil likely to spread?
Variable milfoil fragments tend to establish new plants in water depths of less than 15 feet and in muddy or disturbed areas, such as dredged coves. Possible infestation areas are shown in light green on the milfoil map. Please sign up as a Weed Watcher if you live or vacation near any of these areas.
Weedwatcher Report Form
Complete the Weedwatcher Report Form by clicking HERE.
In an effort to track where WeedWatchers have surveyed for invasive milfoil, track volunteer hours for charitable match grants, and to track notable observations by our WeedWatchers, we ask that they fill out a WeedWatcher Report after each survey.
Links for Further Information
New Hampshire Department of Environmental Services Exotic Species Program -
http://www.des.state.nh.us/WMB/exoticspecies/
This site includes photos of invasive milfoil and other invasive plants found in New Hampshire. Also includes fact sheets, updates on current research, management techniques, and a children’s coloring page.
Maine Center for Invasive Aquatic Plants Virtual Herbarium
http://www.mciap.org/herbarium/
See more pictures of aquatic invasive plants and native look-alikes.
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