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Which Mechanical Option is Right for your Waterbody? Harvesting or Hydro-raking?

by: SOLitude Lake Management   |   May 15, 2017

Written by Industry Experts, Emily Walsh, Environmental Scientist, and Jeff Castellani, Director of Mechanical Operations

Mechanical-Harvesting-and-hydro-raking-e.jpgThere is rarely one specific remedy for helping restore a waterbody. Often times, restoration includes a multiyear management program encompassing a combination of aquatic management tools and techniques, such as herbicide and algaecide treatments, nutrient remediation, aeration and biological augmentation. Mechanical removal is an additional management method that may be incorporated into a restoration program, and has a number of ecological benefits including nutrient mitigation, water circulation and open water habitat restoration.

Mechanical removal encompasses two distinct management tools and approaches: aquatic weed harvesting and hydro-raking. While both provide ecological benefits, it is important to distinguish which option is better-suited for the specific management objectives of your lake or pond.

The aquatic weed harvester is a floating barge that cuts and effectively removes nuisance vegetation and algae from the surface of the waterbody. The plant material is collected and then offloaded, either into a container to be transported offsite or to a designated onshore compost area.

Mechanical harvesting offers an eco-friendly solution that does not create temporary water use restrictions during or after the work. For sensitive aquatic ecosystems, it can act as an alternative to herbicides. Mechanical harvesting can be an ideal management option for annual plants that are invasive or at nuisance levels. The aquatic weed harvester has been proven effective on water chestnut (Trapa natans), giant salvinia (Salvinia molesta), water soldier (Stratiotes aloides), and water hyacinth (Eichhornia crassipes).

The hydro-rake is also a floating barge run by two hydraulic paddle wheels, but is equipped with a 12-foot hydraulic arm with a rake attachment that is used to rake the pond bottom and remove detritus, organic sediment and aquatic vegetation with attached root systems. The hydro-rake, having no on-board storage, must offload the collected material directly onshore or onto a transport barge for removal.

Hydro-raking can be an effective alternative to herbicide and algaecide applications, but it has also proven effective in unison with these treatments. When managing emergent or floating leaf species, such as common reed (Phragmites australis) or water lily (Nymphaea sp.), herbicide application is often the first management approach, followed by hydro-raking. Hydro-raking is commonly utilized after control, to collect the plant biomass and associated root structure, negating it from contributing to the organic matter substrate below. This approach has proven effective on a number of aquatic plants such as cattails (Typha sp.), purple loosestrife (Lythrum salicaria), pickerelweed (Pontederia cordata), watershield (Brasenia schreberi) and Alligator weed (Alternanthera philoxeroides).

Hydro-raking can also serve as a more environmentally friendly and cost effective alternative to dredging. Additionally, if a lake or pond is periodically maintained through hydro raking, the need to perform a large scale dredge project may be negated, saving financial resources and prolonging ecological disruption in the process.

Both aquatic weed harvesting and hydro-raking collect plant biomass before it decomposes and contributes to the organic muck layer, maintaining or increasing overall water depth. In addition to the plant biomass, these mechanical options remove the associated nutrients (phosphorus and nitrogen) that contribute to increased plant and algae growth and, potentially, eutrophication.

These management techniques are used in a wide variety of projects on private, public and state waterbodies to help maintain or restore the open water space of shorelines, coves, inlets and outlets. Depending on the lake management objective and the target aquatic species for control, mechanical projects are usually part of a multiyear program. The next time you look out at your lake or pond, remembering its former attributes and beauty, consider investigating how mechanical services can be applied to help restore balance to your aquatic ecosystem.

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Contact the experts at 888-480-LAKE (5253) for all of your lake, pond and fisheries management needs. 

jeff-castellani-director-of-mechanical.jpgJeff Castellani is the Director of Mechanical Operations with SOLitude Lake Management. Jeff has over a decade of chemical and mechanical aquatic and terrestrial management experience. He holds applicator licenses at the supervisory level in Connecticut, master level in Maine, New Hampshire and Vermont with aquatic category, and additional applicators licenses in Massachusetts and Rhode Island. He maintains licensing and industry certificates for Construction Supervisor, OSHA, Qualified Rigger and Signal as well as Boater Safety.

Emily_Walsh_web2.jpgEmily Walsh is an Environmental Scientist with SOLitude Lake Management who assists the mechanical division with invasive weed control services, surveys, reports, proposals and GIS mapping. She is currently licensed to apply pesticides in Massachusetts and Connecticut. She also has experience in terrestrial invasive species applications, particularly Common Reed (Phragmites australis) and Japanese Knotweed (Fallopia japonica), along with aquatic nuisance vegetation applications.  

SOLitude Lake Management is committed to providing full service lake and pond management services that improve water quality, preserve natural resources, and reduce our environmental footprint. Lake, pond and fisheries management services, consulting, and aquatic products are available nationwide. Learn more about SOLitude Lake Management and purchase products at www.solitudelakemanagement.com.

Topics: Aquatic Weeds and Algae

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