invasive aquatic plants – Aquarius-Systems

Herbicide Costs vs. Mechanical Management on Northern Wisconsin Lakes

Thu, 18 Dec 2025 17:43:03 +0000

For over a decade, lakes across Northern Wisconsin have spent staggering sums of money attempting to control Eurasian water milfoil with herbicides. The Lower Eagle River Chain of Lakes Commission, formed in 2007 specifically to tackle this invasive species, is a case in point.

Eurasian water milfoil grows aggressively, uprooting native vegetation, disrupting aquatic habitats, and interfering with recreation. By 2013, the Commission was spending up to $250,000 per year on herbicide treatments to control approximately 300 acres of milfoil. Grants helped fund these efforts, but by the mid-2010s, funding had dwindled to around $50,000 annually.

After a decade of chemical treatment, the Commission made a bold decision to stop using herbicides altogether. The results? Within a few years, the milfoil population began rebounding. According to the aquatic ecologist who has monitored these lakes for 18 years, the plant is “too big, it’s too much” for manual removal alone, which costs roughly $2,500 per day.

The lesson is clear: eradication with herbicides is expensive, temporary, and environmentally damaging. Even if chemicals were used without regard for ecological impacts, controlling the entire population long-term is not practical.

Instead, a management-focused approach should to taken to target plants that interfere with navigation and recreation rather than attempting total eradication. Mechanical harvesting offers a solution; it doesn’t attempt to eliminate every plant but efficiently manages growth, maintains recreational access, and avoids repeated herbicide costs.

After more than a decade of observation, the evidence is in: spending hundreds of thousands of dollars chasing eradication with chemicals is far less effective than strategic, mechanical management. It’s time for a shift in mindset: toleration and control, rather than endless eradication efforts, may be the only sustainable way forward for our lakes.

Salvinia Threat Emerges in Lake Victoria Waters

Tue, 25 Mar 2025 20:16:39 +0000

A new invasive type of water hyacinth, Salvinia spp., has been discovered in Lake Victoria. It reproduces rapidly, doubling its biomass within 8 days due to high nutrient levels caused by human activities such as improper waste disposal and deforestation. Over 36 tons have already been removed, but the plant continues to spread, threatening fish populations, water transport, and biodiversity by depleting oxygen and reducing water quality.

The newly discovered Salvinia spp. in Lake Victoria likely entered the lake through contaminated fishing gear, boats, or water currents connecting nearby ecosystems. Unlike the regular water hyacinth (Eichhornia crassipes), which forms thick mats on the surface, Salvinia spp. spreads faster and is more resilient under varying environmental conditions. It depletes oxygen more aggressively, suffocating aquatic life and reducing biodiversity. This variant poses a greater ecological threat and requires immediate control measures.

The species negatively impacts fishing, tourism, and water supply, making urgent action necessary.

Mechanical Harvesting Tackles Curly-Leaf Pondweed in East Okoboji Lake

Mon, 18 Dec 2023 19:06:15 +0000

Invasive curlyleaf pondweed has been choking East Okoboji Lake, snarling boat propellers, burning up motors and shutting down swimming, tubing and other water sports in an area that depends on recreation.

The weed’s invasion is driving heated debates about how to control it — from using mechanical removal to administering herbicides that raise concerns about drinking water safety.

An aquatic weed harvester has logged 300 hours this spring, chopping and pulling out about 450,000 pounds of weeds from East Okoboji Lake. The plants are drying in a couple of remote spots, with the hopes that farmers might be able to use them for fertilizer.

Study Finds Plant Diversity Does Not Prevent Aquatic Invasions

Tue, 12 Dec 2023 16:20:49 +0000

A new study from the University of Minnesota challenges a common belief that lakes with diverse plant life are more resilient to aquatic invaders.

The study by the U’s Minnesota Aquatic Invasive Species Research Center looked at 13 years of vegetation survey data collected from about 1,100 lakes by the Department of Natural Resources.

The surprising results: Researchers found no evidence that having a diverse plant community somehow keeps invaders such as curly-leaf pondweed or Eurasian milfoil from taking hold.

Milfoil and Hydrilla the Evil Twins of Invasive Aquatic Plants

Fri, 08 Dec 2023 19:00:18 +0000

Eurasian water milfoil is an exotic invasive species that is thought to have been introduced to the U.S. in the 1800’s in the bilge of ships.
Once established milfoil can never be completely eradicated, but it can be managed with an aquatic weed harvester or repeat treatments of aquatic herbicides. Any relaxing on the spraying regimen however and it comes back as strong as ever.

Fishermen certainly appreciate a good balance of both milfoil and hydrilla for bass populations. Less vegetation and it doesn’t provide enough cover for juveniles, and too much makes it too difficult for the fish to navigate – and for the fisherman to locate them. Too much vegetation also causes difficulties for swimmers, skiers and boaters, as well as clogging powerplant intakes and municipal water systems.

Another definite drawback to a lot of milfoil is low oxygen content and increased eutrophication caused by the decaying of the plant.

After Milfoil Control, Curly-Leaf Pondweed Invades Lake Sunnyside

Fri, 01 Dec 2023 20:14:43 +0000

The war against milfoil in Lake Sunnyside, New York has largely been won — but at the cost of leaving the lake vulnerable to invasion from another plant.

Now, curly-leaf pondweed is taking over the lake, and stewards must fight that one too.

The problem was that milfoil occupied nearly all of the shoreline, the area where sunlight can reach the bottom of the lake, allowing aquatic plants to flourish.

Workers use chemicals that “wiped out” the milfoil but also all the other plants, said Protective Association of Lake Sunnyside board member Eric Sage.

“It devastated the fish population,” he said.

And it left a vacant area for other plants to use, he said. Another invasive species moved in quickly.

Herbicide to Treat Elodea Kills Native Aquatic Vegetation

Wed, 29 Dec 2021 21:49:49 +0000

Elodea is a plant commonly found in aquariums that, if released in the wild, will dominate certain lake or river habitats, choking out native vegetation and altering the food web at all levels.

It increases sedimentation rate, allowing more sediment to settle out of the water. And it can decrease the dissolved oxygen concentration in the water because it is growing so rapidly and using up all of that oxygen. But it also just displaces native aquatic plants, which are good forage for a variety of waterfowl species.

In addition, elodea can ruin the clear-water habitat needed by grayling and spawning salmon, and give an advantage to ambush predators like northern pike.

Applications of aquatic herbicide fluridone have appeared to have worked, and there is no elodea visible in Lake Hood (Alaska) now, but the herbicides killed most of the other plant life in Lake Hood as well.

Weed Harvesting Helps Control Hybrid Watermilfoil in Lake Hallie

Tue, 21 Dec 2021 21:40:36 +0000

Lake Hallie Lake Association is making some headway in the war they’ve been waging against the hybrid watermilfoil weed.

First discovered in Lake Hallie in 2005, watermilfoil is an invasive aquatic plant that has an aggressive tendency to form a thick mat-like layer as it floats on the water. If left unchecked, this plant can cover huge areas of water, blocking sunlight from reaching more desirable plants and making boat traffic difficult.

Using a weed harvesting machine, the Lake Association harvests from May to September, multiple times per week. Over the course of the season, from 200-300 tons of the plant are removed from the lake.

Lake Whitehall Plan Targets Invasive Weeds With Herbicides and Harvesting

Tue, 21 Dec 2021 20:57:26 +0000

The Massachusetts Department of Conservation and Recreation is aiming to reduce invasive plant species in Lake Whitehall in a plan that calls for herbicides and mechanical harvesting.

The reservoir has extensive growth of “exotic nuisance aquatic vegetation,” including fanwort and variable-leaf milfoil, according to a report by ESS Group, a firmed hired by the state.

The planned management program calls for herbicide treatments, mechanical harvesting, hand and diver harvesting, and benthic barriers, a method that uses sediment.

“DCR is also seeking approval for the use of algaecide treatments should they be necessary to control algae blooms following the management of aquatic invasive plant species in the reservoir,” the report reads.

Aquarius Systems Featured on National Geographic for Water Hyacinth Work in Kenya

Tue, 21 Dec 2021 19:17:17 +0000

Aquarius Systems was featured on a National Geographic Cable Channel program broadcast in the United States on April 2nd and 5th, 2003.

The Swamp Devil Aquatic Vegetation Cutter (formerly known as the Cookie Cutter) has been used on Lake Victoria since 1998 to help control dense mats of water hyacinth. A film crew from National Geographic visited our base in Kisumu for three days to shoot exciting footage of the equipment in action. While they were out on the lake, they happened to film a rescue made by the Aquarius staff, who retrieved two fishermen who had been trapped in their boat for two days, stuck in the dense weed growth.

The exotic water hyacinth has severely impacted the Lake Victoria region from both an environmental and an economic perspective.

Watch the Program