Identification of Aquatic Plants

• DNR invasive aquatic plant identification
• DNR aquatic plant identification (includes favorable plants)

Curly-leaf Pondweed

In 2003, a proliferation of this exotic appeared in our lake. It is an exotic noxious weed, which forms dense mats that are difficult to navigate through. It produces stem-like turions that protrude above the water, flowers, then dies off rapidly. It grows in cool weather and even under the ice, and is the first plant to appear in a lake in the spring.

Similar to Eurasian Milfoil, if left unchecked, it will choke out a lake, making it undesirable to live on and lowering property values.

To identify this plant, please see Curly-leaf identification (PDF).

Controlling the weed

In October 2003, the Water Quality Task Force met with representatives of the DNR Exotic Species Control, Fisheries, and Hydrology departments. According to the DNR, there are three ways to control it:

• Spot application of herbicides.
• Mechanical harvesting, either with equipment or hand-pulling and disposal away from the lake and shore.
• Drawdown of the water to dry, freeze and kill the roots.

After discussing the issue with the DNR, city officials and other lake associations, the third method was deemed the least costly and most effective in the short term.

In November of 2003, the lake was drawn down to a depth of 4 1/2' to attempt to freeze and kill the plants. Overall this was a success. However because of concerns regarding negative impacts on wildlife, if a drawdown is done again, it may be timed differently.

The DNR has been monitoring it and it appears to have spread at a slower rate except perhaps in the shallow bays, but still must be controlled so as not to reach the levels it has in the past.

To see a map of the last curly-leaf survey, please download Curly-leaf 2006 map (PDF).

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Aquatic Vegetation Removal

Residents are encouraged to pull curly-leaf if they see it in the spring. Be careful not to pull favorable weeds such as sago pondweed or waterlilies.

To identify plants, please see the DNR website at http://www.dnr.state.mn.us/invasives/index.html.

The Lake Orono Water Quality Committee is working on a plan to address curly-leaf in public areas and for those who are physically unable to pull the weed.

You may clear a portion exotics by hand in front of your property without a permit, provided:

• The area to be cleared must be no larger than 2,500 sq. feet.
• The area must not extend more than 50 feet along the shoreline or one-half the length of your shoreline, whichever is less.
• A boat channel up to 15 feet wide and as long as necessary to reach open water may also be cleared.

Be sure to destroy the plants away from the lake and do not compost them.