Blog Archives

Mechanical Harvesting an Economical Choice

It is exhausting reading about lake after lake after lake becoming infested with an over abundance of aquatic vegetation.  This plant material not only negatively affects water quality, the health of the fishery, recreation, aesthetics, but it is financially devastating as well.

It affects tourism; bait shops, marinas, hotels, restaurants.  It affects lake property owners; taxes, resale values.  And it affects the community as whole when it comes time to right the wrong caused by the overabundance of vegetation.

Determining how to manage the vegetation often times divides communities and neighbors.  There are enormous lists of pros and cons related to each method and $$$$ seems to be a hot spot.

Proponents of mechanical harvesting deem it as expensive.  Some articles list expense as a problem with aquatic plant harvesters ans a control method.  Of course the equipment does involve a capital investment, but amortized over the 10+ year lifetime and it becomes a very cost effective option.

This 30 year old Aquatic Plant Harvester is still operational and in use.

This 30 year old Aquatic Plant Harvester is still operational and in use.

A weed harvester is also economical to operate, using only 1.5 gallons of diesel per hour.  Workers are often volunteers or part time summer help and if regular maintenance is performed (just like you take care of the car you drive) no expensive repairs are required.  Plus as a bonus, aquatic weed harvesters have resale value.  Contractors often look for used equipment and since the machines operate for 10 – 20 – 30 years, they sell quickly.

When it comes time to select a control method for aquatic vegetation, please contact us before judging mechanical harvesting as too expensive.  While the upfront price may seem too much, think of it as a long term investment.  An investment into the next decade!

At 20 years old, this Aquatic Plant Harvester both looks and operates well.

At 20 years old, this Aquatic Plant Harvester both looks and operates well.

Keeping Our Waterways Weed Free

Little thought is given to aquatic weeds unless you live or recreate on the worlds waterways.  The aquatic plant harvester industry has grown in response to those concerns.

Steam Powered Aquatic Weed Harvester

With Pictures of steam powered cutter boats dating back to the late 1890’s, we know that excessive plant growth has been a problem for a long time.  At first, the problem was dealt with manually.  People came up with clever tools to help make weed cutting easier.  Others tried hand pulling the plants, but the going was slow.

Hockney Weed Cutter

The true origins of the harvesting industry began with a weed cutter boat built by the Hockney Company in Silver Lake, Wisconsin, in 1903.  It is interesting to note that this machine was not originally built to meet recreational purposes; it was made in response to fussy Chicago housewives!  Around the turn of the century, ice was harvested from Wisconsin lakes destined for Chicago iceboxes.  The housewives there didn’t like cleaning out the weeds when the ice melted.  Hockney designed this small boat, which featured a reciprocating cutter bar and duck-feet-like paddles for propulsion, to cut down the weeds in the fall so that clean ice could be harvested in the winter.

Ice Harvesting on the Milwaukee River

From this modest beginning many attempts were made to modify and improve these early cutter boats.  In the early 1960’s, brothers John and Doug Dauffenbach founded D&D Products Incorporated located in North Prairie, Wisconsin and began manufacturing a more modern harvester which are still in production today, operating as Aquarius Systems.  Like an underwater lawn mower, an aquatic weed harvester simultaneously cuts the vegetation, collecting and storing the weeds on board.  The cutter head located on the front of the harvester uses sickles similar to those found on farm equipment, and generally cuts from one to six feet deep. A conveyor belt on the cutter head, which is always in motion, brings the clippings onboard the machine for storage. Once full, the harvester travels to shore to discharge the load of weeds.

Prototype Aquatic Weed Harvester

Harvesters come in a variety of sizes, with cutting swaths ranging from four to twelve feet in width and up to five or six feet deep. The onboard storage capacity varies as well, and is measured in both volume and weight. Harvester storage capacities generally range from 100 to 1000 cubic feet of vegetation by volume, or from one to eight tons. They are usually propelled by two paddle wheels that provide excellent maneuverability and will not foul in dense plant growth. Harvesters may be propelled by twin hydraulically powered props.

Mechanical harvesters offer an environmentally sound method of controlling nuisance vegetation.  As these weeds are removed from the lake, the water is immediately ready for use and there are no restrictions on use of the area that might be experienced with herbicide or some biological control treatments.

Mechanical Harvester Cutting & Collecting Severed Vegetation

Removal of this biomass prevents its eventual decay and settling to the bottom, helping to reduce sedimentation in the lake. There is some nutrient removal with harvesting too, as the nitrogen and phosphorous that is bound up in the plant exits the water body. Harvesting is usually not lethal, leaving behind an oxygen and habitat producing plant, which is often desirable.

The aquatic weed harvester has come a long way from its crude and cumbersome origins.  The future holds infinite possibilities.  Some of the concepts being researched include: New paddle wheel designs for greater efficiency, a new hull design that more closely resembles the hull of a boat, and a remote controlled transport barge.  We’re also researching ways to turn the harvested plant material into a marketable product.  As the hydraulics industry evolves, this too will have an impact on changes in the harvesting industry.

We cannot be entirely sure how the harvester of the future will look, but with nuisance aquatic plant growth reaching epidemic levels globally, the industry is certain to be around for many years to come.  We’ve learned over many, many years that nothing is impossible.

Aquarius Systems Aquatic Weed Harvester

Aquatic Weed Cutting & Harvesting Success

Ninety-eight percent of Malawi’s electricity supply comes from five hydro plants on the Shire River.  An increase in floating aquatic weeds and debris caused serious operational problems at the stations and resulted in millions of dollars spent on repairs.  For example, the intake structures at one plant were so blocked by accumulated weeds, water could not pass through. This situation created a vacuum in the intake tunnel while the machines were running; the result was a collapse of the intake screens. Repairing the screens and returning the station to service cost more than $12 million. 

After several years and a couple of failed weed management programs officials needed a better way to minimize the effect of aquatic weeds to hydro plant generation and restore the beauty of the Shire River at the same time.  That “better way” involved a mechanical means to combat the weeds including an Aquarius Systems weed shredder (Swamp Devil™), a mechanical weed harvester, a shore conveyor, and a trailer conveyor. 

The automatic vegetation shredder was immediately put into operation. This boat contains two blades at the front, which are used for both propulsion and as cutters. It chops aquatic weeds into pieces about 15 millimeters long.  In addition to collecting weeds that have been chopped by the automatic vegetation cutter, the harvester can collect weeds that have not been chopped. Once the harvester is at capacity, it off-loads the weeds onto the shore conveyor and returns to work. In the mean time the shore conveyor transports the cut weeds to the unloading site on shore.  Trucks then take the weeds to a designated depository site. 

The success of the project can be measured on several levels. There have been virtually no plant shut downs after nearly three years running and the hydro station owners can operate its hydro facilities in an almost debris-free environment. This has allowed greater efficiency of the hydro stations and has improved the image of the company to its customers and stakeholders.  The success is also measured by the social benefits in the nearby area. First, it has created jobs. The project employs a marine engineer and other marine technicians, in accordance with the national water machinery regulations.  Second, depositing the weeds in farm fields is improving soil fertility. This allows local farmers to reduce their reliance on artificial fertilizers, which coincidentally is what provided the nutrients for the aquatic plants to grow and multiply to begin with.

The Weeds at River Walk

The Weeds at River Walk – Part 2.

These are some great pictures of our weed harvester!

Milfoil — Beating back the invader

Milfoil — Beating back the invader

Wednesday, August 1, 2007

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This harvest feeds no hunger, just a compost pile.

The benefit from the harvest is safety and convenience for users of parks along the Columbia River: no tangled feet and easier launching for boaters.

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Ben Mendoza and Randy Smith, Chelan County PUD park maintenance personnel, spend four days a week July through August clearing parks of Eurasian milfoil, an aquatic noxious weed. The parks are between the Beebe Bridge and Rock Island Dam.

“It’s kinda like mowing lawn,” says Smith about running the milfoil harvester.

The harvester cuts the milfoil below the water level, catches and lifts it onto a conveyor and secures it in a holding tank until the harvester docks and the milfoil is removed.

Smith and Mendoza have worked together since 1997 and have been harvesting milfoil for the state and county parks along the Columbia River in Chelan and Douglas counties for two years.

A day harvesting milfoil begins with getting the harvester ready for the water.

They lower the paddle wheels, take the “Oversize Load” sign off the back and erect a large shade umbrella over the seating area. Even with the umbrella, they lather on the sunscreen and get ready for a hot day on the water.

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Also with them are inflatable vests, safety goggles, ear plugs, lots of water and iced Gatorade.

The men back a trailer holding the harvester into the water, then push the machine off the trailer with the help of a hydraulic lift.

While one person runs the harvester on the water, the other stays on shore, performing basic maintenance on the pump and trailer.

When the harvester is full, it is maneuvered toward shore, where the conveyor is shifted into reverse and the load is dumped onto a truck bed. The load is then taken to a compost heap on park grounds.

Keith Truscott, environmental and permitting manager for Chelan County PUD, says milfoil has such a high water content that even a very large pile will break down to almost nothing when it dries.

By the time the truck has come back from dumping the weeds, says Smith, the harvester is often full again and the next batch of harvested milfoil is ready to be taken to the compost pile.

Mendoza and Smith agree that Dave Coble, their crew leader and the man who trained them to use the machine, holds the record for most loads harvested in a single day at 26. Mendoza and Smith claim they aren’t really keeping count, but Mendoza says his personal record is about 14.

The size of the park, technical difficulty and the amount of milfoil to be harvested determines how long it takes to finish each park and how much is harvested each day.

Mendoza says the job is easier when the water level is lower. The milfoil and any hazards are easier to see then.

Both he and Smith concede the most difficult park is Will Risk Memorial Park, commonly known as Entiat park. Foundations from the original town of Entiat, buried underwater after the erection of Rocky Reach Dam in 1961, are near the surface there. The two slow down when harvesting that area to prevent damaging the machine.

If something on the harvester needs fixing, often it can be done while still on the water, with the tools kept on board.

Harvesting can get a little scary when the gates at dams open, Mendoza says. With the stronger current and a full load, the harvester can’t move very quickly and has to fight against the current.

Duties working in park maintenance vary and include plowing snow in the winter, mowing lawns and pruning.

The two men work four days a week, Monday through Thursday, avoiding Fridays and weekends because the boat launches and parks are busier on those days.

“We try to be considerate and stay out of people’s way,” says Smith.

Rochelle Feil: 664-7153

feil@wenworld.com

What is an Aquatic Weed Harvester?

Aquatic Plant Harvesters offer an environmentally sound method of controlling excessive aquatic plant growth and nuisance vegetation in waterways of all sizes. These heavy duty work boats are highly efficient in the management of submerged, emergent and free floating aquatic vegetation.

Like an underwater lawn mower, an aquatic weed harvester cuts aquatic vegetation, collecting and storing the weeds on board. Aquatic weed harvesters are fitted with a pick up conveyor at the forward end of the machine, which can be lowered up to six feet deep to cut weeds. One horizontal and two vertical cutter bars sever the vegetation as the machine moves forward through the water, and, when the storage hold becomes full, the weed harvester returns to shore to unload.

Depending on the size of your lake, the type of your weeds, the percentage of weeds you would like to remove, and how quicky you would like to harvest them, we will work with you to design a fully customizable weed harvester to meet your exact needs.  

Although many of our mechanical weed harvesters are customized to match the needs for your lake, a variety of models are available at stock sizes ranging between 100 feet3 (or 1,500 lbs) and 1,050 feet3 (or 16,800 lbs) for capacity of cut vegetation held on board.

DNR “Mows” Dogwood Lake

DNR “Mows” Dogwood Lake
August 18, 2011 Washington Times Herald

Department of Natural Resources employee Ron Hauser runs an aquatic weed harvester at Glendale Fish and Wildlife Area on Wednesday afternoon. The harvester was being used on the lotus pads and coontail growing in the lake.

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