Save Minnewawa Association was formed in 1977 and they purchased their first aquatic vegetation harvester in 1982. Since the harvester has been in use, not only have the amount of weeds decreased, but the water clarity has significantly increased.

A big reason for this is because there are fewer weeds dying in the lake and decomposing in the bottom of the lake. Also, the weeds contain a huge amount of phosphorous which is being removed along with the weeds. The more phosphorous in a lake, the more algae growth, therefore the lower the water clarity.

The board has heard the suggestion of controlling the weeds by using chemicals instead of the weed harvester. The cost of the chemicals is very prohibitive though. It was $250,000 dollars and the lake had to be treated twice a year for the first 5 years; a price tag of a half million dollars. Compared to approximately $25,000 a year it takes to run the weed harvester.

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The new method uses water hyacinth, a weed known for its ability to spread rapidly over water bodies. It is used for cleansing polluted water bodies owing to its remarkable capacity of absorbing pollutants.

In the new study, hyacinth was made into a powder and then mixed with water containing chromium-6. The powder was allowed to settle down and after two minutes the liquid above the powder was removed and analyzed for chromium-6. It was found that chromium-6 levels decreased significantly in water.

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The Court’s decision was to dismiss an appeal made by the Hokio Trust, allowing Horizons Regional Council’s weed harvester to undergo a test harvest on the Lake Horowhenua in New Zealand, this Spring.

Horizons natural resources and partnerships group manager Dr Jon Roygard says weed harvesting has been identified by NIWA as the key intervention to reduce the toxic effects of the Lake on aquatic life and recreation.

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When you look at lovely water gardens in backyards and at businesses — and feel soothed by the serenity they convey — you would not guess that they represent troubled waters for ecosystems in the mid-Atlantic region.

The explosion in popularity of water gardening has resulted in the proliferation of aquatic invasive species, according to Diane Oleson, a Penn State Extension educator based in York County, who created an educational program that shows water gardeners how to avoid giving aquatic invaders a free ride.

Invasive plants tend to displace native plants over time and create an unhealthy ecosystem because a lot of them form huge, dense, one-species stands in which other plants can’t grow. “Animals don’t eat them because the species that would control them are back in Asia or Europe or wherever they came from,” Oleson explained.

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– Immediate relief from nuisance plants that interfere with navigation and recreation
– Immediate use of the water for swimming or irrigation
– There is nothing foreign introduced to the environment when using mechanical control
– Biomass is removed from the water and along with it the nitrogen, phosphorus and potassium that are bound up in the vegetation
– Harvesting does not kill the vegetation, but instead gives it a hair-cut, leaving behind living plants that continue to provide oxygen and habitat for the other organisms

– The living plants left behind continue to absorb the polluting nutrients that are used for growth
– Harvesting vegetation from the lake greatly reduces the tons of biomass that will eventually die and collapse at the end of the season. This biomass will decompose, consume oxygen, and release nutrients back into the water column to grow more weeds and algae in the future.
– Harvesting the biomass also reduces the build-up of muck and sediment on the bottom that occurs from the rotting weeds
– The Harvester is a tool to be used to improve the fishery. For example “Cruising Lanes” can be formed into certain weeds beds to provide access for fishermen, and for predator fish too; the predator fish will graze the edges of trimmed weeds beds to find prey.
– Over time plants become stressed and grow more sparse and shorter in height in frequently harvested sites
– Lake weeds make a great compost and soil conditioner. The decomposed vegetation compares to cow manure in terms nutrient content. Also, it contains no seeds that can grow on land.

– Harvesting is a highly selective process. Exactly where you steer the machine is exactly where the plants will be cut.
– Aquatic Plant Harvesters are available in many sizes with a variety of features to be customized to your application
– A Harvester is an essential tool in the lake manager’s tool box. It can be made to cut shallow or deep, narrow or wide, fast or slow, depending on what is needed.
– A Harvester compliments other lake management strategies, including herbicide use. For example, the canopy of vegetation can be harvested BEFORE a chemical treatment is done. This technique may save money because it enables the lake manager to use less herbicide. And it will reduce the negative environmental impacts of using chemicals by reducing the tonnage of biomass that settles to the bottom to decompose