Mechanical weed harvesting may be the best solution for Tainter Lake
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by LeAnn R. Ralph
MENOMONIE — Mechanical weed harvesting may be the best solution for controlling weeds in Tainter Lake, although it would not necessarily be the only method used.
Nick Johnson of Aquatic Plant Management out of Minocqua spoke to the Tainter Lake Rehabilitation District Board of Commissioners at the July 18 meeting about weed harvesting.
The Board of Commissioners would plan to do weed harvesting next year if lake district residents approve the funding.
On the day of the July 18 meeting, Johnson and other representatives for the Tainter Lake Rehabilitation District took a tour of the lake.
Aquatic Plant Management specializes in managing both invasive species and native plants that have grown to the point where they are a nuisance, Johnson said.
There are three methods used to remove weeds from a lake: traditional hand harvesting with divers; chemical applications; and mechanical harvesting, he said.
Each tool has its place, and no lake is usually a one-size-fits-all for weed harvesting, Johnson said.
Hand harvesting by divers is appropriate in a small area of a couple acres where some weeds must be removed but other native aquatic plants should be maintained. Mechanical harvesting is appropriate for larger areas, he said.
If there are many acres where there are invasive plants, a chemical application may be appropriate, Johnson said.
In some cases, chemical applications are not an option. In a system with moving water, like Tainter Lake, chemical application will not work very well. There also is a regulatory hurdle because the Wisconsin Department of Natural Resources is averse to using chemicals, he said.
When water has a current, the chemical does not stay long enough where it is needed to actually kill off the plants, Johnson explained.
Mechanical harvesting has more flexibility and can be used in areas where the DNR might be willing to approve the use, he said.
Last winter there was unusual weather that was warm with little snow. Then this spring, the weather was still dry. But early in the summer, there was quite a lot of rain. Since there is more current in some areas because of the large amounts of rain, those areas are staying more open than they usually would be, Johnson said.
Navigability
The question about removing weeds concerns navigability of the lake, Johnson said.
The mechanical harvester is like a grain combine, with a cutter head on the front and conveyor belts that move the cut material to the deck of the barge. The swath is seven feet wide and six feet deep, he said
When the harvester barge is full, there is a dump trailer on shore, and the barge is dumped into the trailer. The harvested weeds are then hauled off for disposal, Johnson said.
Oneida Lake out of Woodboro, Wisconsin, had about 100 acres of dense weed growth. The plan was to cut the weeds to create 50-foot wide common navigation lanes, he said.
The weed harvester has a field computer that guides the harvester and when the job is finished, produces a map done by Google maps. The map can be downloaded to a phone so people can use it to navigate in and out of their docks, Johnson said.
Generally the growth rate of lake weeds is about a foot per week. After the initial cut, the second cut might be delayed and is dependent on what is happening with lake conditions in a particular year, he said.
The northeast portion of Tainter Lake is green and thick with weeds that make it closed to boat access, Johnson said.
The Board of Commissioners will have to decide what access looks like and whether there will be navigation lanes or horseshoe shaped areas, he said.
The green that is in the northeast portion of Tainter Lake is duck weed, Johnson noted.
Tainter Lake has excessive nutrient inputs coming in from upstream that encourage the growth of aquatic plants, he said.
Mechanical harvesting removes the biomass of the weeds. When chemicals are applied, the biomass stays in the lake and decays which contributes to the nutrient load in the water, Johnson said.
Criteria
The Board of Commissioners will have to decide which areas are most conducive to harvesting, and that would typically be where the lake is used the most, Johnson said.
There is no sense in harvesting a tucked-away bay where the nearest house is a hundred yards away, he said.
Site selection criteria is exceptionally important. The Board of Commissioners would not want to get into a situation where people are asking why one area was cleared of aquatic material but another area was ignored, resulting in people complaining about why this person’s area was harvested but “not my area,” Johnson said.
The criteria for site selection must be black-and-white, he said.
The idea is to focus on common use areas that benefit the largest number of people, Johnson said.
Most lake districts do not have unlimited funds to harvest weeds from an entire lake, he noted.
30 feet
Jerry Porter, a member of the Board of Commissioners, noted that the first 30 feet out from the shoreline “are yours.”
People can do what they want with the 30 feet, and if they want to remove weeds close to their shoreline, that is their business, he said.
Not all shoreline is the same, and some sections of shoreline have more weeds than other sections, Porter said, noting that last year, he and members of his family had removed five tons of lake weed along his property and had thrown it up on shore.
Dredging
Grant Peissig, a member of the Board of Commissioners, asked how many lakes across the state are doing weed harvesting and how many lakes are doing dredging.
There are regulatory hurdles for dredging, and it is expensive. The cost could be several hundred thousand dollars to dredge a small area, Johnson said.
Mechanical weed harvesting is fairly common, he said.
Aquatic Plant Management has three full-time harvesters that are busy at all times during the summer, Johnson said.
Some lake groups have purchased their own weed harvesters, he said.
In addition to finding the money to purchase the weed harvester, it also has to be staffed and the equipment must be maintained, Johnson said.
At the end of the year, a lake district might have 20 people who say they will happily volunteer to operate the weed harvester the next summer, but then when June rolls around, “crickets,” no one will volunteer to do the work, he said.
Mechanical harvesters cost about $300,000, Johnson said.
If the Tainter Lake District could keep up with the staffing and the maintenance, then it might be worth considering purchasing a mechanical harvester, he said.
Tourism
The lakes around Minocqua are busy with tourism. Are the weed harvesting projects funded by a lake district, by the county or by a municipality? Peissig asked.
Harvesting is mostly funded by lake associations and districts, Johnson said.
There is not much help available from the state, especially for native plants. There might be more help for invasive species, he said, adding that there is some grant funding available outside of the state.
Problems with aquatic plants will affect tourism, Johnson said.
For example, if there was a bed and breakfast in a certain area, but the lake was full of weeds just out from the bed and breakfast, that would probably affect the bed and breakfast’s business, he said.
There is no grant money for aquatic plant management. That is why the lake district is proposing to spend $39,000 next year on the removal of aquatic plants, Porter said.
If the Tainter Lake Rehabilitation District were to buy a mechanical harvester, the district “might” (with an emphasis on might) get half of the purchase price back from a grant, he said.
Weed harvesting is a necessary evil that is on-going, Porter said.
Fragments
In response to a question from the audience on harvesting and the possibility of fragments migrating and growing elsewhere, Johnson pointed out that fragments from harvesting lake weeds are a necessary evil.
Company personnel do their best to collect the weed fragments, but there is less of a concern about native aquatic plants spreading, Johnson said.
Eurasian watermilfoil, for example, would pose a definite concern for spreading when fragments are released, he said.
Eurasian watermilfoil is highly invasive. After a single fragment of a stem or some leaves has been introduced to a lake after being stuck to a boat or a boat trailer backed into the water, the entire lake can end up being choked with it after a few years. Eurasian watermilfoil grows up to two inches per day.
There is a density and distribution threshold for aquatic plants, and in certain situations, a team of divers might be used so that the native plants are not disturbed, Johnson said.
One lake district had heard that cutting Eurasian watermilfoil later in the year, in October, would result in less density next year. There was a very slight decrease the next year, but it was difficult to say whether it was due to cutting the plants later in the year or because of lake conditions, he said.
Curly leaf
Johnson said he had not seen any signs of Eurasian watermilfoil in Tainter Lake but that the lake did have curly leaf pondweed.
According to the United States Department of Agriculture National Invasive Species Center website, curly leaf pondweed is native to Eurasia, Africa and Australia and was introduced in the United States in the mid-1800s. The impact of curly leaf pondweed is that it forms dense mats that inhibit the growth of native species and interfere with recreational activities.
The plants can grow up to 15 feet tall, meaning they can grow in 15 feet of water, and they tolerate low water quality.
Curly leaf pondweed seeds itself by turions that sprout in the fall, Johnson said.
A turion is described as a type of bud that can grow into a complete plant.
Chemical treatments can be used on curly leaf pondweed, but the turions are still in the “seed bank” at the bottom of the lake and will grow back the next year. After repeated chemical treatments, the growth slows down until the turions eventually are used up, Johnson said.
People should be vigilant about putting their boats into Tainter Lake, making sure there is no Eurasian watermilfoil attached before launching, he said.
Other plants that Johnson observed in Tainter Lake were flat stem pondweed, elodea and coontail.
Elodea, which grows along the bottom, can drift and be pushed around by the wind so that large mats of it can end up along the shoreline, he said.
According to some on-line sources, elodea provides cover for aquatic insects and fish and provides underwater habitat during the winter months.
Coontail stays green and can continue to grow during the winter.
Moving forward
If the funding is approved by residents of the Tainter Lake Rehabilitation District, then the Board of Commissioners can establish the goals of the aquatic plant removal project and establish the parameters of where the weeds will be removed, Johnson said.
The commissioners can work on the plan over the winter, and part of the consideration will be what the DNR will approve, he said.
The plan can always be cut back to match the money that is available, Johnson said.
The Tainter Lake Rehabilitation District would not have enough money to clear cut the entire lake, Porter said.
Lake Chetek has had a weed removal program for several years, and the tons of weeds harvested has decreased by 75 percent, he said.
Water quality is the driver of cyanobacteria, and opening up some bays in Tainter Lake may help for water circulation, especially since this is a riverine system, Johnson said.
There was a bidding process for aquatic plant removal, and that is how the Tainter Lake Rehabilitation District Board of Commissioners arrived at Johnson’s company for $39,000, said Al Brown, chair of the Board of Commissioners.
The Tainter Lake Rehabilitation District held an annual meeting on August 3 at the Menomonie High School Auditorium.
