Mechanical Controls: Suction-Assisted Diver Harvesting

Suction-Assisted Diver HarvestingSuction-assisted diver harvesting is a standard removal process that is widely used for aquatic plants such as Eurasian watermilfoil. The operation involves literally hand-pulling the weeds from the lake bed. It requires water pumps to move a large volume of water to maintain adequate suction of materials that the divers are processing. The material placed by the divers into the suction hose along with the water is deposited into onion bags with water leaving through the holes in the bag mesh. The bags must have a large enough 'mesh' size so that silts, clay, leaves and other plant material being collected do not immediately clog the bags and block water movement.

This method was tried in the Cayuga Inlet in late 2011 in areas where hydrilla was found too late to be included in the herbicide treatment. Unlike watermilfoil, however, the mechanical removal process was found to be too aggressive for hydrilla; the process resulted in the fragmentation of the plant and likely contributed to washing small plant particles back into the recently cleared area.

Based on these initial results, it is uncertain that this method will work for hydrilla removal in general. However, a more complete analysis will be done and possible changes in the mechanical processes may be proposed that offer more hope for use of this method as an alternative to herbicide treatment in some situations.

For a complete assessment of this process and analysis of its effectiveness in the Inlet, see Assessment of Diver-Assisted Dredging.

 

Last Updated: June 13, 2013

Last updated: June 13th 2013 - 1:36pm