About 150 species of aquatic plants grow in Minnesota. A few, called "exotic species," are not native to the state; controlling their growth is sometimes necessary to reduce competition with native plants. Controlling native plants is often sought when they interfere with swimming or boating.

So what can lake home owners do about that greenery growing in the lake? That depends on the types of plants targeted for removal.

DNR Regulations

In Minnesota, plants growing in public waters are owned by the state. Homeowners can control many types of these plants when they impede recreational use of the lake, but a permit from the Minnesota Department of Natural Resources may be needed. The DNR wants to protect native vegetation and lakes from unnecessary harm while enabling lakeshore homeowners to control some aquatic vegetation.

The Minnesota DNR classifies aquatic vegetation in three categories:

1. Submerged - plants growing from the lake bed to the water's surface

2. Floating leaf - plants such as water lilies

3. Emergent - plants that grow out of the water, including bulrushes and cattails

Those needing a permit

Any control of emergent vegetation requires a DNR aquatic plant management permit, issued through the DNR's Regional Fisheries offices. Use of chemical herbicides for any of the three types of vegetation in public waters also requires a permit, as does use of "untended mechanical devices" designed to clear vegetation.

Those not needing a permit

Homeowners can remove up to 2,500 square feet of submerged vegetation without a permit. That 2,500 square feet can include up to a maximum of 50 feet along a shoreline or one-half the lot length if shoreline owned is less than 100 feet, whichever is less.

For example, a homeowner with 100 feet of shoreline on a lake wants access for swimming and boating. Submerged vegetation extends 150 feet lakeward from shore adjacent to his property. The homeowner can legally remove submerged vegetation in an area 50 feet along shore by 50 feet lakeward (2,500 square feet) plus a 15-foot-wide channel through submerged vegetation starting at the outside edge of the 2,500-square-foot cleared area. If vegetation in the area extends 150 feet from shore, this would result in the homeowner being able to clear 50 feet by 50 feet near shore plus a channel 15 feet wide, extending 100 feet lakeward from the 2,500-square-foot area.

Floating leaf vegetation is more protected than submerged vegetation. Owners can cut and remove a 15-foot-wide channel to open water through floating leaf vegetation without a permit.

The first time a lake home owner requests a permit, a DNR representative will conduct a site inspection to assess the extent of the nuisance, the homeowner's use of the lake and the type of vegetation in question. Inspections cannot be conducted until the weather is warm enough for plant growth, usually beginning by late May. Permits are typically issued in one to two days once inspection is completed. The DNR also distributes information on various herbicides and companies that sell them.

Some people find the DNR's rules restrictive but Dave McCormack said he hears a lot of positive comments from homeowners who appreciate the DNR's work. McCormack is an aquatic plant management specialist, Central Fisheries Region, Minnesota DNR.

Protection of native plants is important, he said, as is minimal destruction of all aquatic vegetation. Aquatic plants provide habitat for fish, wildlife and invertebrates; reduce wave action and resulting shoreline erosion; filter run-off and buffer shorelines from pollutants.

Lake home owners desire weed control

Many lake home and cabin owners disagree with the DNR's limits on controlling vegetation and want the ability to remove additional amounts. "Overprotecting lake weeds interferes with swimming, boating and fishing, and reduces property values," said Don Pennings, co-owner of Lake Management, Marine on St. Croix, Minn. "Weeds also interfere with aesthetic value and endanger weak swimmers."

Pennings, who used to work for the DNR as an aquatic biologist, now provides aquatic weed controls and sells products to control aquatic plants. The products are approved by the Environmental Protection Agency and the Minnesota DNR, and are not harmful to non-target organisms, he said.

"If aquatic weeds are considered a natural resource, they're the most renewable natural resource that we have," Pennings said. "They generally grow back in six to eight weeks. They don't need a whole lot of protection." Aquatic plants in general are way overprotected, he said, including native species which he considers overpopulated.

As one example of his displeasure with the DNR, Pennings cites its lack of efforts to control the exotic species Eurasian watermilfoil. "Milfoil was discovered in Lake Minnetonka in the late 1980s," he said. "Now it has spread to 140 or so lakes. They've had 15 years to tackle this problem."

In addition, Pennings said the Minnesota DNR hired four or five international aquatics experts in 1994 to look at aquatic management programs in the state. They ended up recommending many changes in DNR programs but the DNR hasn't implemented any of them.

"What upsets me the most is that the DNR is not basing its rules on scientific data. Their decisions and policies are arbitrary and capricious. They pick numbers out of the sky."

Control exotic species

Paul Isensee, a homeowner on Blue Lake in Zimmerman, Minn., wants greater consistency in enforcement of DNR regulations and greater attention given to controlling exotic species, especially Eurasian watermilfoil, purple loosestrife and curly-leaf pondweed. He recalls how the Blue Lake Association, working with a former DNR regional office employee, spent time and money in a multiyear program to control curly-leaf pondweed. But when the DNR employee retired, his successor allowed less latitude in controlling the exotic species. For example, the association needed to leave eight acres of curly-leaf pondweed untouched in Blue Lake last year.

Purple loosestrife	Eurasian milfoil

As another example, he said that in 1990, Eurasian milfoil was found in 38 Minnesota lakes. By 2003, the number of lakes reached 150. Isensee wants to see improved protocols in place for controlling exotic species - both to take care of problems today and to prevent what could be worse. As an example, he described another exotic species that is far more invasive than Eurasian milfoil: hydrilla, which has yet to reach Minnesota lakes.

"We have plenty of safe chemicals approved by the EPA that can control or eradicate these weeds," Isensee said. "We want to control exotic species and protect native species."

Minnesotans for Healthy Lakes

Isensee is co-chair of a group called Minnesotans for Healthy Lakes. "Our goal is enhancing the water quality of all Minnesota lakes," he said. "That involves water clarity and control of exotic species."

Exotic species also tend to be early and fast growers and can crowd out native species, Isensee said. "A huge problem," he said, "is the canopy that many exotic species form, blocking out sunlight to native species of vegetation." Lack of sunlight also decreases phytoplankton and zooplankton populations; the latter is eaten by fish.

Many fishermen believe that lake weeds are good for fish populations, Isensee said. "But that isn't necessarily right, nor is it necessarily wrong. It depends on the type of weed."

Minnesotans for Healthy Lakes want to inform the public about exotic species and present the groups expectations to the DNR. The group wants the DNR to change its policies toward tighter control of exotic species. If not, the group will press for legislative changes to do the same.

"It's not clear to us where the buck stops," he added. "We won't quit until it's done. Every day we don't do something about this means Eurasian milfoil is invading another lake."

More information is available at www.mnhealthylakes.org.

Perspective from a limnologist

Most lakes in Minnesota, and certainly most of those south of Brainerd, are moderately fertile, said Steve McComas, limnologist and consultant with Blue Water Science, St. Paul. If a lake is fertile, something will grow in it. If it's not aquatic plants, then it will be algae.

"We usually try to manage for clear water and aquatic plant conditions," McComas said. "The alternative is a lake filled with algae, and turbid water."

McComas recommends that lake home owners try to tolerate as many aquatic plants as they can. "However, if they are impeding boat navigation or other recreational activities, they can be managed. The question is what's more important - access to recreation or a natural setting?"

Only the bare minimum of plants should be controlled, according to McComas, advising that lake home owners remove the minimum amount of plants in order to enjoy the lake.

"We all remember going to resorts, walking on the sugar sand beaches with no plants growing there," McComas said. "That's our perception of how a beach should be. But in reality, in the natural world, that's more the exception than the rule.

"A lot of times, resorts are built on the best shore of a lake -- the shore with a natural sandy beach," he continued. "And the owners may be raking the beach on a daily basis. Some even have machines that sift the sand. Many public beaches are highly maintained, too." If the beaches and near-shore areas were not maintained, vegetation would probably become reestablished.

Use of herbicides have their place in vegetation control, McComas said. Some are selective and others, including contact herbicides, are not. "There is ongoing debate as to their use. Certain subtle adverse impacts are hard to quantify."

However, even an invasive species like Eurasian watermilfoil can act like a native plant in some lakes and can be left alone, McComas said. "But if it grows to be a nuisance, then it may be time to control it."

What value do aquatic plants provide?

The benefits of a lake’s aquatic plants are many. Consider this response to a question about removing lake weeds posed on the Minnesota Pollution Control Agency Web site:*

“Aquatic plant communities provide critical fish and wildlife habitat. Native emergent plants are natural shoreline stabilizers because they reduce wave action that can erode shores, and act as filters to reduce nutrient runoff into the lake. Emergent plants also provide important cover, nesting and feeding areas for fish and wildlife. Plants such as yellow-waterlilies and broad-leaf pondweeds provide shade, shelter and foraging opportunities for fish. Fish also seek cover in beds of muskgrass and bushy pondweed.

“The taller, denser foliage of coontail and northern watermilfoil provide excellent habitat for aquatic invertebrates. (Eurasian milfoil, however, is an exotic species and thus causes its own set of problems. . .) Bushy pondweed is one of the most important plants for waterfowl, which consume the stems, leaves and seeds of the plant. The tubers and foliage of water celery are a favorite food of canvasback ducks. Seeds of all of the pondweeds are also eaten by waterfowl and the leaves may be grazed by muskrat, deer and beaver.

“Therefore, any removal of these plants should be done in a manner that limits the overall plant community. A healthy diversity of native aquatic plants can also help prevent exotic species from becoming established in the lake."

*http://www.pca.state.mn.us/water/lake-faq.html#weeds

By Barb Umberger

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