eurasian milfoil – Aquarius-Systems

Invasive Weeds and Herbicides Are Threatening Fish in Flint Lake

Tue, 06 May 2025 17:00:10 +0000

A closer look at how Eurasian milfoil and chemical treatments are harming aquatic life

Flint Lake on Valparaiso’s north side is in trouble. Invasive aquatic weeds, especially Eurasian milfoil, have become so overgrown that they’re even interfering with fish population surveys. During a recent Department of Natural Resources (DNR) survey, biologists had to stop two or three times just to clean the weeds off their boat’s propellers.

Herbicide Treatments: A Short-Term Fix with Long-Term Consequences

While treatments for Eurasian milfoil might seem like a good solution, they often come with serious environmental trade-offs. Herbicides do not actually remove the plants—they simply kill them where they grow. This leaves large amounts of decaying plant matter in the water, which can significantly reduce oxygen levels. As the plants rot, they consume oxygen that fish and other aquatic life depend on, potentially creating dead zones that are uninhabitable.

To make matters worse, the milfoil in Flint Lake is becoming more resistant to the most commonly used chemical treatments. And if the herbicide isn’t specific to milfoil, it can endanger beneficial native plants as well.

Native Plants: Critical for Young Fish and Water Quality

These native aquatic plants are more than just vegetation—they’re lifelines for young fish. “Anytime you damage these plants, you’re killing hundreds of thousands of babies,” DNR specialist said. Smaller fish use these plants to hide from predators and as feeding grounds. Destroying them reduces fish survival rates and upsets the balance of the ecosystem.

Mechanical Removal Isn’t a Silver Bullet Either

Even mechanical methods have their risks. Fragmenting Eurasian milfoil—chopping it up—can actually help it spread. Each small piece of the plant has the potential to take root and grow elsewhere in the lake.

A Call for Smarter Management

The situation at Flint Lake underscores the urgent need for responsible and effective aquatic plant management strategies. It’s not enough to kill the plants—we must remove them in a way that protects fish habitats, promotes water quality, and prevents further spread.

Judge Overturns Approval of Herbicide Use in Lake George

Fri, 17 Mar 2023 19:12:29 +0000

Created by melting glaciers thousands of years ago, Lake George is 43,471 acres, 32 mile long, up to 2.5 mile wide and up to 200 feet deep. Located at the southern end of the Adirondack Park in Upstate New York, Lake George is the primary driver of regional tourism, generating $2 billion in annual economic activity.

Lake George is among the clearest and cleanest large lakes in the World. Over 90% of the watershed remains as natural forestland with half of that protected as forever-wild Forest Preserve. And, Lake George serves as the primary source of drinking water for surrounding communities and residents.

Like many lakes, Lake George has been impacted by invasive Eurasian milfoil. First discovered in 1986, it has been managed over the past 30 years at a cost of over $5 million. To date hand-harvesting and matting have been used to control the milfoil, in 2020 186,590 pounds (about 93 tons) of milfoil was removed from Lake George.

The milfoil continues to grow in Lake George and in an effort to eliminate the dense milfoil beds, the Lake George Park Commission, in charge of managing the lake wanted to try aquatic herbicides and received a permit to do so. However, the Lake George Association and a large number of the public raised objections to the use of herbicides in their beloved Lake George.

The Lake George Association felt there were too many unknowns about its impact on nontarget species, to native plants, animals, and even to human health for those people who still use the lake for their drinking water. The association sued to stop the use of the aquatic herbicide use and a state Supreme Court judge ruled in favor of the herbicide treatment.

October 2022 Newsletter

Tue, 10 Jan 2023 17:49:23 +0000

The Future of Conservation

A Message From Our Leader: Should We Learn to Live With Invasive Such as Eurasian Milfoil?

Data and the Future of Conservation

Floating Hyacinth Mats Provide Food Security

Upcoming Conferences:

Washington State Lake Protection Association 35th Annual Conference
Midsouth Aquatic Plant Management Society 41st Annual Conference
Upper Midwest Invasive Species 14th Annual Conference
North American Lake Management Society 42nd International Symposium

Larger Weed Harvester Expected to Improve Quality of Weed Removal

Wed, 29 Dec 2021 22:03:00 +0000

The Cazenovia Town Board’s first meeting of the new year — and with recently elected Councilor Jimmy Golub seated at the table — saw not only the making of annual organizational appointments for the town government, but also the announcement that the town is soliciting bids to potentially purchase a brand new lake weed harvester to replace the current one.

The town’s seven-foot-wide aquatic weed harvester — used to remove the invasive Eurasian watermilfoil from the lake — was purchased used in 2014 for $60,000. Since then, it has removed hundreds of metric tons of milfoil from the lake, but last year was beset by mechanical difficulties that left it inoperable after July 4. The town rented Cayuga County’s 11-foot-wide weed harvester for one week and then used the Madison County, New York’s, weed harvester for the rest of the summer.

Cazenovia lake harvester crews this year removed two-thirds more milfoil than they did last year, partially because the Cayuga County machine was so much bigger than Cazenovia’s machine.

Mechanical Harvesting Removes Water Chestnut on the Charles River

Tue, 21 Dec 2021 22:28:12 +0000

The Charles River Watershed Association and local citizens have obtained funding to conduct large-scale mechanical harvesting to remove roughly 50 acres of water chestnut and other invasive weeds.

The Charles River Lakes District in Massachusetts is a popular destination for canoeists, kayakers and rowers, but the pollution from stormwater runoff resulted in an increase in nutrients resulting in the growth of water chestnut, Eurasian watermilfoil and fanwort which interfered with those activities.

The weed harvesters have will harvest for a few weeks in August before the water chestnuts drop their seeds and will start up again in the spring of 2014.

Weed Harvester Removes 2,656 Tons of Milfoil From Cazenovia Lake

Tue, 21 Dec 2021 21:48:00 +0000

In the absence of chemical pesticide treatment on Cazenovia Lake in New York this summer, crews used an aquatic weed harvester to control the invasive watermilfoil.

During the four months of weed harvesting on the lake, town crews removed 354 boatloads — 2,656 tons — of invasive milfoil weeds from the lake. The harvesting also removed 11,000 pounds of nitrogen, 17,000 pounds of phosphorous and 5,800 pounds of potassium from the lake.

In 2015, town crews harvested 423 metric tons of weeds from the lake.

If the harvester wasn’t on the lake this year, it probably would have been unusable.

Study Finds Herbicides for Eurasian Milfoil Can Harm Native Aquatic Plants

Tue, 30 Nov 2021 22:28:16 +0000

Lake managers might be hurting native aquatic plants – instead of helping them – when they use chemicals to control invasive plants on entire lakes.

New research by Wisconsin DNR Lakes and River Team Leader Dr. Alison Mikulyuk shows native plant communities can struggle when chemicals are used to target invasive Eurasian watermilfoil.

It appears the effects on native plants are worse than if there were no treatment at all.

Okanagan Lake Milfoil Program Clears Infested Areas With Long-Term Weed Harvesting

Fri, 05 Nov 2021 16:28:17 +0000

The Okanagan Basin Water Board milfoil program has been so successful over the past five decades. Aquatic weed harvesters used in significant areas with milfoil infestation on Okanagan Lake, British Columbia, Canada are now clear of the invasive plant.

Meanwhile, the water board continues to work with the province and environmental consultants to expand existing milfoil treatment areas.

Read More https://www.castanet.net/news/Vernon/326344/Milfoil-harvesting-in-Okanagan-lakes-has-been-a-success-but-more-required

Prop Chop Spreads Eurasian Milfoil in Black Lake as Officials Debate Control Options

Fri, 05 Nov 2021 15:44:30 +0000

County legislators are considering providing some type of support to a group trying to get rid of the Eurasian milfoil infestation in Black Lake, New York.

The milfoil problem is exacerbated when propellers on boats going through the lake chop it up (prop chop) the and spread its seeds. Legislators debated what methods could stop that. One group wants to dig a 50-foot channel to keep the propellers away from the milfoil. Another method could be to rent a machine that mechanically harvests the milfoil.