Suction Harvesting

Suction Harvester 6934 Where the milfoil growth is thick hand harvesting is not adequate. Since each plant has to be pulled at the roots and every part of the plant has to be completely removed from the lake, we employ a device like a huge underwater vacuum cleaner, called a suction harvester. A high volume pump mounted on the pontoon boat sucks water through two long four inch hoses.

Divers with Hoses 6929Divers with scuba gear take these hoses down to the root end of the plants. They can pull the plants with the roots, and the whole thing is sucked into the hose and whisked away. One of the continuing problems working on the lake bottom is diminished visibility when the silt on the bottom is disturbed. Pulling milfoil plants severely clouds the water, but the suction harvester pulls the silted water away too, making it much easier to see.

Trash Rack 6951The hoses empty out into a floating contraption attached to the pontoon boat, which the divers colorfully call the trash rack. I am not sure the name describes its function or its condition. In any case, the streams of water carrying milfoil and silt spray against its perforated sides. The milfoil stays inside, and the water escapes.

Climbing in 6939 Scraping 6944The two divers who are not at the moment underwater picking milfoil and stuffing it into the hoses climb into the trash rack and scrape the milfoil from the screen, keeping the openings from getting clogged with debris and the milfoil waste from overflowing into the lake.

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