nutrient removal – Aquarius-Systems

St. Albans Bay Harvesting Helps Reduce Nutrient Pollution

Fri, 22 Dec 2023 16:40:46 +0000

Weed growth in St. Albans Bay in Vermont was not as bad this past summer as anticipated according to Steve Cushing, President of the St. Albans Area Watershed Association (SAAWA).

Last year, high, turbid waters and a layer of sediment carried into the lake by flooding and rainfall reduced weed growth, explained Cushing. With clear water and low lake levels this summer, those familiar with the bay were expecting more weed growth than they’ve seen, but Cushing believes the sediment may also be helping to suppress weed growth this summer.

SAAWA removes 400 to 500 tons of weeds from the lake each summer with the help of an Aquarius Systems Aquatic Weed Harvester. The weeds contain a lot of water, Cushing explained and once they dry out, 40 to 50 tons of organic matter remains. Removal of the weeds prevents the weeds from dying and decaying in the water where they would release phosphorus and nitrogen, the very nutrients that feed algae blooms.

Currently the weed growth is outstripping our ability to pull them out of the lake, but we are convinced there are benefits to removing as much growth as possible, before it decomposes, spoiling water quality, increasing phosphorus as well as producing conditions for blue green algae growth.

Harvesting Invasive Plants for Fuel and Fertilizer

Mon, 04 Dec 2023 17:40:29 +0000

Researchers who work in wetlands in Michigan are taking a new approach to invasive plants. They’re harvesting them for fertilizer and fuel.

When you’re in the middle of the Shiawassee National Wildlife Refuge, you don’t realize how massive it is. It’s 10,000 acres of marshes and bogs, forest and farmland. To put the size in perspective, Manhattan is roughly 15,000 acres.

Brendan Carson is a researcher from Loyola University Chicago. He’s working on a project at the wildlife refuge centered around harvesting cattails. Carson says the project is designed to let the cattails grow all summer, absorbing the nutrients like a sponge, before the harvesting takes place.

Carson says harvesting invasive plants is more cost effective than spraying them with chemicals.

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.

What Is Aquatic Weed Harvesting and What Results Should You Expect

Thu, 16 Dec 2021 22:21:51 +0000

What is Harvesting?

Operational Considerations for your lake.

Expected Results from a Weed Harvesting Program.

Most aquatic plant harvesting systems will cut and remove submersed plants to a depth of five or six feet. As this biomass is removed from the lake, the water is immediately ready for use and there are no restrictions on use of the area that might be experienced with herbicide or some biological control treatments.

Removal of this biomass prevents its eventual decay and settling to the bottom, helping to reduce sedimentation in the lake. There is some nutrient removal with harvesting too, as the nitrogen and phosphorous that is bound up in the plant exits the water body. Harvesting is usually not lethal, leaving behind an oxygen and possibly habitat producing plant, which may be desirable in some situations.

Many harvester managers have witnessed a reduction in nuisance plant growth after a few years of repeated harvesting. The plants showed signs of stress and came back thinner, lower growing, and more scattered than before. In some cases desirable plants were able to out compete the nuisance plant growth.

Kitsap Lake Uses Phoslock and Weed Harvesting to Reduce Algae Blooms

Fri, 05 Nov 2021 20:43:44 +0000

It’s a familiar sight to residents living on the shores of Kitsap Lake in Washington: each summer, around the beginning of June, a bright green algae begins to creep across the water. These blooms can be harmful to people and pets and have forced closures of Kitsap Lake and its beaches every year for the last five years

This year, a different approach was taken. Starting in June, contractors sprayed the lake with a compound called Phoslock, which helps remove phosphorous from the water. Then an aquatic vegetation harvester trawled across the south end of the lake, chopping down underwater weeds and hauling them to shore. The goal – to remove as much phosphorous from the lake as possible.

Sediment in the lake – from decomposing weeds, lawn fertilizer, stormwater runoff – produces excess phosphorous, which acts as fuel for algae blooms. Relatively few outflow points on the lake result in a slow turnover rate of water and poor nutrient cycling, according to a 2011 Kitsap Public Health District report.

The harvester removes plant life and opens the water up to circulation, allowing for the water to mix and more sunlight to reach the deepest parts of the lake

Florida Scientist Says Mechanical Weed Removal Beats Chemical Spraying for Lake Health

Fri, 05 Nov 2021 19:41:23 +0000

Spraying chemicals can be dangerous to the environment in many ways. But for Floridians, they can contribute to harmful algae blooms and damaging releases along the coast.

There are other ways to remove invasive plant species that may not require chemical spraying. James Douglass, an environmental scientist at Florida Gulf Coast University says the other methods could have several benefits and chemical spraying is actually the worst way to solve the problem.

Douglass agrees that other methods create a win-win for everyone. “It takes that rotting material out of the water and actually uses some of the materials from those aquatic weeds as fertilizer and return nutrients to the land where they’re needed instead of having them cause algae blooms in the water,” he said. An aquatic weed harvester not only opens waterways for navigation, but it is very effective in removing excess plant material.

Benefits of Weed Harvesting for Water Quality and Nutrient Removal

Thu, 04 Nov 2021 18:04:26 +0000

Benefits of Weed Harvesting
Dr. Stephen J. Souza
Lake Hopatcong Commission Environmental Consultant

One of the most obvious management activities of the Lake Hopatcong Commission is the weed harvesting program. Some may view this as a simple “mowing” of the Lake. However, much more is accomplished than simply opening boating lanes and improving swimming. The harvested weeds represent a significant amount of biomass, and associated nutrients, that if not removed would otherwise add to the siltation of the Lake and contribute to its future eutrophication.

In its first three years of operation, because of the concerted, coordinated efforts of the Lake Hopatcong Commission, over nine million pounds of weeds were removed from the Lake. This could not have been accomplished without the state-of-art harvesting equipment and the dedicated staff of the Lake Hopatcong Commission. From a water quality perspective, the removal of this much weed mass is very important. The phosphorus associated with these weeds is roughly 1,200 pounds.

Although this may not sound like a lot, a single pound of phosphorus can support over 1,100 pounds of algae. Thus, through the weed harvesting efforts of the Lake Hopatcong Commission in New Jersey, phosphorus, that otherwise would be recycled through the Lake and fuel future weed and algae growth, is removed. This has a direct positive benefit to the long-term water quality of the Lake and the control of the Lake’s eutrophication. As such, the weed harvesting program contributes in more than the obvious way in the revitalization of the lake and the improvement of its water quality.

Study Finds Strategic Weed Harvesting Can Remove Phosphorus and Support Clear Lake Management

Mon, 01 Nov 2021 21:18:37 +0000

Intensive in-lake and watershed management caused Kohlman Lake, the northernmost lake in the Phalen Chain of Lakes in Minnesota, to go from a relatively turbid to a clear water state. Aquatic plants responded to the clean waters by growing up to the surface. The change in lake state and a comprehensive water quality monitoring dataset gave researchers an excellent opportunity to develop and assess a strategic aquatic plant harvesting approach to a balanced lake management plan that centers on navigation, recreation, aesthetics, water quality and ecological function.

Aquatic plants provide several ecosystem services such as habitat, food, cover and shading, temperature moderation, and nutrient uptake and sequestration. The overall approach to mechanical weed harvesting was conservative and the plant mass removed from the lake was about 14% of the peak mass that would be present without harvesting.

Harvesting removed 24% of the total phosphorus (TP) captured by aquatic plants and this accounted for 4% of the TP load derived from external sources. In addition, the cost of TP removal by aquatic plant harvesting is quite economical when compared to phosphorus management practices that take place in upland watershed areas. Data from this study suggest that harvesting certainly presents cost-effective opportunities for TP removal and has the potential to factor into dynamic and creative watershed management approaches.

Reprinted with permission from NALMS. The original article published in Lakeline, Volume 40, No. 4 Winter 2020.

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Weed Harvester Approved to Remove Macroalgae and Reduce Harmful Algal Blooms in Georgica Pond

Mon, 01 Nov 2021 21:00:39 +0000

An aquatic weed harvester was used to remove macroalgae from Georgica Pond in New York from 2016 through 2018 and on a limited basis last year, an effort to inhibit harmful algal blooms, including toxic cyanobacteria, or blue-green algae. Approval has just been granted for the the mechanical harvester to be operated from June to September this year and required for the next five years as well.

The Friends of Georgica Pond Foundation, a group of pondfront property owners, know that removing the plant material is particularly helpful in lowering phosphorous levels in the pond. By doing so, “harmful algal blooms and ecological crisis” can be prevented. There is a definite correlation between operation of the weed harvester and improved water quality.

Black Lake Weed Harvester Removes 6,000 Pounds of Invasive Milfoil to Improve Boating Access

Tue, 19 Oct 2021 21:14:47 +0000

In the last few decades, the lake’s weedy, northern-most portion has clogged hulls and deterred boaters from entering the lake from the Oswegatchie River. Patches of weeds greet the water’s surface near every dock, and nearly invisible from a distance on a windy day, matted greenery creates a basin of weeds seven-feet-deep in some spots.

As part of a summer-long effort to cut a channel in Black Lake (New York), the Black Lake Association used an aquatic weed harvester to cut and remove invasive Eurasian watermilfoil. On one September afternoon, the Black Lake Association harvested roughly 6,000 pounds of invasive wet weeds in less than two hours.

The harvested vegetation was taken to a local dairy farm to be used as fertilizer.