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Milfoil Treatment Plan for Swains Lake
Variable milfoil dense.JPG


We are responsible for 50% of milfoil funding for 2024. This means SLA needs to pay $32,845. Please help us protect Swains Lake!

Thank You to EVERYONE Who Has Donated So Far

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What to Do
Current Milfoil Status


The milfoil plants begin to absorb the chemical (ProcellaCOR) immediately when it is placed in the area of the patch.   The boat is an airboat, and it is retrofitted with a large tank to hold the chemical which is mixed with water when applied.  A number of hoses apply the herbicide directly underneath the surface of the lake.   This prevents "spray" from blowing on shore. 



On Monday, June 12, Solitude treated 74 acres of the lake.  They did advise us more treatments in the future.   The State will be back on the lake in the Fall to do a survey to help us identify future needs.



We did a check on the heavier spots and it is definitely turning brown – boat launch, the dam area and Mica Point -we have been advised that within 3-4 weeks after treatment they will die off.    (pictures below)



From Linda Briggs – Lake Host Manager:  

Those of us who have had conversations with our regulars, those guys that go out at 4:30 AM and return at 3:00 PM, have heard that the weeds have practically disappeared in the channel to and from the ramp, and the trailers that pull out are almost clean of weeds. We are telling everyone that we need to remain vigilant because we know we did not get 100% of the milfoil.


 Existing BROKEN or FLOATING before TREATMENT:  

The milfoil that was already broken off and floating around the lake can still take root, because as a floating stem, it won't absorb the herbicide, (floating stems have no roots to absorb this chemical which targets the root system).   So,  this will be an ongoing process on a yearly basis, although Amy expects each year we will need less and less.   So, as we asked last year, if you see it floating, please try to pick it up (pool skimmer, etc) and remove from the lake – if rooted – please do not pull it out as it spreads wildly that way.

What to Do
What You Can Do

Avoid Areas of Milfoil

In the areas on the map where milfoil has been identified, do not go near them. Any disturbance to the milfoil gives it a chance to break off and float to seed and spread.

Remove FLOATING fragments ONLY

If you see milfoil fragments that are floating up to your shore, carefully remove them and throw them away. You must be careful when removing the fragment as they can easily snap and spread.

Keep a Lookout

If you notice anything suspicious that has not already been marked on the map, immediately notate your location, try and grab a picture, and contact us via email. Make sure to not disturb the area!

Are you a Skilled Diver?

We are looking for divers to take a course and get certified on removing exotic weeds. There are specific requirements and we have a group of lake members we are working to coordinate a class for. Please email us to inquire.

Become a Lake Host

Now more than ever, we need to have a consistent presence at the public boat launch to inform and monitor the boats entering our lake. Please email us if you can offer volunteer hours or paid hours of $12 per hour.

What SLA is Doing

Working with NH DES and NH Fish & Game on application process for permitting/etc for herbicidal treatment and diving removal.

Signage posted at boat launch informing the public of milfoil on our lake. These signs are legal and approved by NH Fish & Game (responsible of the launch).

Lake Host team members are communicating with boaters to inform them of the current status and to avoid areas.

Forming a committee of SLA members who are divers and getting them certified to work with exotic species removal.

We are reviewing with NH Fish & Game the status of the boat launch.

Area Reps are making rounds to communicate with all watershed homes of the current status.

Fact Sheet

What is Milfoil?

Milfoil is a submerged aquatic plant with fine, densely packed, feather-like leaves whorled around a main stem. It can grow up to 15 feet and may exhibit a three- to six-inch green spike-like flower above the waterline in late June or in July. A cross-section of the stem will reveal “pie-shaped” air chambers. This exotic species of milfoil has been in the state since the late 1960s, and can currently be found in over 75 waterbodies in New Hampshire. There are six native milfoil species present in the state that do not cause problems, as they are low growing and do not form monocultures, unlike variable milfoil. Eurasian milfoil is another non-native milfoil found in New Hampshire, but it is less of a threat than variable milfoil due to our water chemistry (Eurasian milfoil tends to be found in waters with higher pH ranges than those found in New Hampshire).

How Does Milfoil Spread?

Boat propellers chop milfoil plants into small fragments. These fragments float on the surface and are at the mercy of the wind and lake currents. In a short time, roots form on these fragments. If washed ashore, these plants eventually take hold, creating a new colony of milfoil. The cycle goes on until every suitable area is filled in with these weeds. An alternative form of the plants develops during low water.

This vegetation type is more succulent than the submersed form and can persist for moderate periods of low water. NHDES has recently collaborated in a study to evaluate the viability of milfoil seeds and the research showed that milfoil seeds are very viable and have a high regeneration rate, though survival of the seedlings is thought to be relatively low. Regardless, seed production in a dense milfoil bed is high, and seeds are thought to be a probable source of new plants, even following extensive control measures (seeds are resistant to herbicides). Data suggest that long-term monitoring and appropriate follow-up activities are needed to truly reduce or potentially eradicate infestations. Regular surveys by NHDES biologists or volunteer Weed Watchers are needed to find new growth early, so that small-scale control measures can address the problem before it spreads.

It is unlikely that seeds are responsible for lake-to-lake spread; fragments are still the primary cause of that problem.

Information taken directly from NH DES Fact Sheet on Variable Milfoil:

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