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HBPA first began experimenting with pond harvesting in 1994 on Grist Mill Pond near the Wayside Inn in Sudbury, Massachusetts.  The objectives of harvesting have been to find the most efficient method of removing hydrodictyon (algae), elodea and water chestnut (aquatic weeds) from the Hop Brook ponds and, in the process, to mitigate the immediate problem of the stench and visual impact of rotting algae during the summer months.  Although harvesting cannot prevent eutrophication of the ponds caused by the present excessive levels of nutrient loading, it has proven effective in improving the quality of life for residents neighboring the ponds and, hopefully, the wildlife inhabiting the ponds.  Harvesting is also seen as a potential technique for restoration of the ponds once the nutrient loading from the Marlborough easterly wastewater treatment plant has been reduced to sub-critical levels.

Manual harvest Several methods of removing algae have been tried.  Lacking any equipment designed specifically for aquatic harvesting, the initial attempts used a floating boom to surround a floating mat of algae.  The boom was then used to tow the mat to a shore-stationed device that could remove it from the water.  A motorized conveyor belt and a sewage pump were tried as experimental removal devices. Although significant amounts of algae could be removed by these methods, they proved to be slow and extremely labor intensive.
Early Attempt at Manual Harvesting
The most successful harvesting implement has proven to be a mechanical aquatic weed harvester, a barge-like machine designed to gather both floating mats and submerged aquatic weeds while propelling itself through the water.  The harvester has a front-mounted submersible sickle bar cutter that cuts the submerged plants, following which is a conveyor that delivers the harvested product to an onboard storage bin.  When the storage bin becomes filled, the harvester is driven to a shore-stationed conveyor that transfers the product to a dump truck.  The truck then delivers the material to a designated upland composting area.  The truck driver also operates the shore conveyor.
   Aquamarine H7-400 harvester
In recent years an Aquamarine H7-400 harvester owned by the Great Meadows National Wildlife Refuge in Sudbury has been generously loaned for harvesting the Hop Brook ponds.  The Town of Sudbury Highway Department has provided hauling and mechanical services.  

Of the four ponds in the Hop Brook system in Sudbury, Grist Mill Pond, Stearns Mill Pond and Carding Mill Pond have been mechanically harvested.  The pond at the intersection of Dutton Road and French Road is privately owned.
Harvesting Water Chestnut on Carding Mill Pond

In 2016 the Great Meadows National Wildlife Refuge replaced the Aquamarine harvester with a smaller harvester that is is easier to transport and can access areas of the ponds with shallower water depth.

To view the 2016 Harvesting Report click here.
For further information contact:
Susan Collins, Harvesting Coordinator