Milfoil on Swains Lake.

Updated: 07/27/2026

Protecting Swains Lake from variable milfoil and other aquatic invasive species is one of the core missions of the Swains Lake Association. Through a close partnership with the New Hampshire Department of Environmental Services (NHDES) and professional lake management specialists, we work year-round to keep our waters clean, navigable, and healthy.

🎉 LATEST STATUS UPDATE: July 27, 2026

30 Gallons Harvested & Rest of Lake Confirmed Clean!

We have fantastic news following our rapid community response to the July 12 milfoil discovery in the cove near the dam.

1. Full-Lake Survey Results: The Rest of Swains Lake is Clean!
Immediately following our initial report, Georgia Bunnell and her NHDES team conducted a thorough, lake-wide survey. NHDES confirmed that the rest of Swains Lake is completely clean. No other milfoil patches were found anywhere else in the lake!

2. Rapid Diver Action: 30 Gallons Removed
Because the SLA proactively handles environmental permits and contractor agreements every winter, we were ready to move instantly without waiting weeks for state paperwork.

Even though our partners at AquaLogic were fully booked out, owner Dom squeezed Swains Lake right into the schedule. Dom sent out his father, John—lovingly known as the "Grandpa of Divers" and one of the original milfoil harvesters in New Hampshire. On Monday, July 27, 2026, John conducted a hand-harvesting dive and successfully removed 30 gallons of variable milfoil from the lakebed!

3. Next Steps & Buoy Protocol
John feels confident he harvested the entire patch, but he will return in a week or two to conduct a follow-up inspection dive to guarantee 100% removal.

🛑 Caution Notice: The white marker buoy will remain in place in the cove near the campground and dam. Please continue to completely avoid boating, paddling, or swimming near the buoy so boat propellers do not disturb the area before the follow-up dive.

4. Community Teamwork in Action
This rapid success story was made possible by incredible collaboration across our lake community:

Matt N.(SLA Advisor) for spotting and reporting the patch early.
Georgia Bunnell (NHDES) for getting out on the water so quickly for the full survey.
The Campground Management for graciously opening their private boat launch so our dive team could launch close to the site.
Dom & his Dad John ("Grandpa of Divers") at AquaLogic for squeezing us in and taking care of our lake!

Donate

Report a Sighting

⏳The Swains Lake Tracking Timeline: How We Got Here

Understanding the history of our mitigation efforts helps explain why continuous tracking and proactive management are our absolute best lines of defense. Here is the historical timeline leading up to today:

Phase 1: The Initial Herbicide Control

Following a targeted herbicide treatment a few seasons ago, dense populations of variable milfoil were successfully knocked down. This major investment by the SLA and NHDES set the stage for a period of excellent lake health.

Phase 2: Spring 2026 Survey — "Two Years Clean"

May 8, 2026: Georgia Bunnell (NHDES) completed a thorough spring survey of Swains Lake and reported zero milfoil sightings, marking our second consecutive season with a completely clean spring report!
The Outcome: Because the lake was clear of target growth at ice-out, Swains Lake did not require a costly spring herbicide application.

Phase 3: July 2026 — Early Detection & Rapid Removal

July 12, 2026: SLA Advisor Matt Niswendir spotted a small patch in the cove near the dam during a kayak patrol, marked it with a buoy, and submitted map pins to NHDES.
July 2026: NHDES surveyed the entire lake, confirming the rest of the lake was clean.
July 27, 2026: Aqua Logic diver John ("Grandpa of Divers") hand-harvested 30 gallons from the cove spot. Follow-up dive scheduled.

💡 Why Your SLA Membership Matters

This rapid turnaround is exact proof of why annual membership dues are so vital. Applying for state permits and setting up contractor agreements every winter is a major task and a financial commitment, but it pays off when action is needed.

Without those permits secured months in advance, we would have been stuck in paperwork while this patch expanded across the cove. Your $25 annual membership dues directly fund these permit fees, contractor retainers, and rapid-response logistics.

🤝 How You Can Help

Keeping Swains Lake milfoil-free is a community-wide effort. Here is how you can do your part:

👀 Keep Your Eyes Open: If you notice any suspicious, feather-like green weeds while out swimming, boating, or paddling, do not attempt to pull them yourself (as fragments can drift and root elsewhere). Note the location, take a photo if possible, and report it immediately. 👉 CLICK HERE
🧼 Clean, Drain, Dry: Always ensure your boats, trailers, kayaks, and fishing gear are entirely clean of mud, plants, and water before launching into Swains Lake and immediately after pulling out.
⚓ Support the Lake Hosts: Our SLA Lake Hosts stand guard at the public boat launch all summer to inspect incoming vessels. This program is entirely funded by your $25 annual membership dues.

👉 Click Here to Renew or Join the SLA for 2026 and Support Our Lake Protection Efforts!

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: https://www.des.nh.gov/sites/g/files/ehbemt341/files/documents/2020-01/bb-23.pdf