How to get rid of lake weeds depends on how big your problem is, whether the plants are native or invasive, and how much you want to spend. There’s no single best method. Hand-pulling, bottom barriers, mechanical harvesting, herbicide, and diver-assisted suction harvesting each win in a different situation. This guide compares them head to head so you can match the method to your shoreline, and stay inside the Wisconsin rules while you do it.
Before you pick, know one thing: most of the plants in a healthy Wisconsin lake are native and useful, and the state protects them. Invasive plants like Eurasian watermilfoil and curly-leaf pondweed are the ones you can go after hard. If you’re not sure which you have, that changes both what you should do and what you’re allowed to do, so start there. See our permit guide for the rules.
How do the methods compare?
| Method | Pros | Cons | Best fit |
|---|---|---|---|
| Hand-pulling | Cheap, selective, no permit in the 30-ft zone | Labor-heavy, small scale, fragments can spread milfoil | Pier and swim area, spot-pulling invasives |
| Bottom barrier / benthic mat | Kills a defined zone, no chemicals, lasting | Needs a permit, smothers native plants too, needs upkeep | A set swim or dock area |
| Weed roller | Ongoing DIY control, no chemicals | Up-front cost, covers a fixed arc only | Owner who wants one area kept clear for years |
| Mechanical harvesting | Removes plants and nutrients, covers big areas | Expensive, non-selective, can spread fragments, permit needed | Large open weed beds, lake-district programs |
| Herbicide treatment | Fast, covers large areas, selective products exist | Annual cost, NR 107 permit always needed, doesn’t remove biomass | Coves, large frontages, invasive knockdown |
| DASH | Very selective, removes roots, spares natives | Slow, costs more, billed by time | Targeted invasive milfoil removal |
Hand-pulling and raking
The simplest method, and the only one you can do across a real area with no permit, as long as you stay in the single 30-foot corridor along your shore (or you’re pulling invasives). Grab the plant low and pull the whole thing, roots included, then rake up and haul off every floating fragment. For Eurasian watermilfoil that last step matters, because a broken piece can drift, root, and start a new colony. Hand-pulling is perfect for keeping a pier and swim lane open. It just doesn’t scale to a weedy cove.
Bottom barriers and benthic mats
A bottom barrier is fabric or screen laid on the lakebed to block sunlight so nothing grows underneath. It’s chemical-free and it keeps a swim area clear for a season or more. The trade-offs: it kills native plants along with the nuisance ones, it needs anchoring and occasional cleaning so gas and silt don’t lift it, and it needs a DNR permit. Barriers fit a defined dock or swim zone, not a whole shoreline.
Weed rollers
A weed roller is a motor-driven arm that sweeps the bottom in an arc, rolling plants and muck flat and keeping a set area open. You buy it once and run it for years, which suits an owner who wants a fixed swim area clear without paying for a service every season. It only covers the arc it can reach, and like a barrier it works a defined zone rather than a broad frontage.
Mechanical harvesting
A harvester is a floating machine that cuts plants a few feet down and conveys them aboard, like mowing underwater. It clears large areas and physically hauls the plant material (and its nutrients) out of the lake, which over time can shift a lake back toward native plants. The downsides are cost, the fact that it cuts everything in its path rather than selecting, and the risk of spreading fragments if it’s run carelessly. Harvesting is almost always a lake-district or association program, not a one-owner buy. Lake Pewaukee has run a district harvesting program since 1947.
Herbicide and aquatic treatment
Aquatic herbicides knock down weeds fast over large areas, and selective products can target invasive milfoil while sparing many native plants. That speed is why it’s common for big coves and invasive outbreaks. But it always needs an NR 107 permit, it leaves the dead plant material in the lake to decay (which feeds algae), and it’s a repeating cost because the permit is seasonal and plants regrow. Timing and product choice matter a lot, so this is usually a job for a licensed applicator, not a DIY afternoon.
DASH: diver-assisted suction harvesting
DASH is the surgical option. A diver works the bottom and pulls target plants by hand, roots and all, feeding them up a suction hose to a boat. It’s the most selective method for taking out invasive milfoil while leaving native plants in place, and pulling the roots means less regrowth. The catch is speed and cost. Crews clear only a few hundred square feet an hour, so it’s used for targeted invasive work, often paired with a herbicide treatment on the same lake.
Which method fits your situation?
- Just my pier and swim area: hand-pulling, or a bottom barrier for a set zone.
- I want one area clear every year without hiring out: a weed roller.
- A big weedy cove or open-water bed: herbicide or mechanical harvesting, usually with a permit and often through the lake group.
- Invasive milfoil I want gone without killing native plants: DASH, or a selective herbicide.
- The whole lake is choked: that’s a lake-district conversation, not a single-owner fix.
Frequently asked questions
What’s the best way to get rid of lake weeds?
There isn’t one best way. For a small area, hand-pulling or a barrier. For a large area, harvesting or herbicide. For selective invasive removal, DASH. Match the method to the size and the plant.
Will pulling milfoil make it spread?
It can if you snap the stems and leave fragments, because each fragment can root. Pull whole plants and remove every floating piece.
Do these methods kill native plants too?
Barriers and non-selective harvesting or herbicide hit natives along with the nuisance plants. Hand-pulling and DASH are selective. Native plants are protected, which is one reason the no-permit removal zone is capped at 30 feet.
Can I get rid of weeds permanently?
No. Lakes grow plants. The realistic goal is keeping your use area open and knocking back invasives, not a weed-free lake.