Management of Aquatic Invasive Plants

Purple loosestrife plant

Invasive Aquatic Plant Management permits

The DNR works with citizens to monitor the distribution of invasive aquatic plants in the state, prevent further spread, and manage problems caused by these plants. A permit may be required to remove nonnative invasive aquatic plants.

To apply for a permit to manage invasive aquatic plants, complete the permit application This is a PDF file. You will need Adobe Acrobat Reader to download it. and submit it to your local aquatic invasive species specialist. Additional instructions This is a PDF file. You will need Adobe Acrobat Reader to download it. are available.
 

Issuing Invasive Aquatic Plant Management Permits

The following criteria will be used to evaluate applications for invasive aquatic plant management permits. A successful application will receive a "yes" to questions 1-8 and a "yes" to questions, 9-11, if relevant.

  1. Has the application for an IAPMP been completed and submitted properly?
    1. Has a waiver from the requirement to provide signatures been requested?
  2. Is the target invasive aquatic plant(s) found in the proposed treatment area?
  3. Is the proposed treatment technique selective for the target invasive plant(s)?
  4. Is the purpose of the proposed treatment to significantly reduce the lakewide or baywide abundance of the target invasive plant(s)?
    • Treatments that work at a scale to cause a significant reduction of the lakewide or baywide abundance can range from a small set of scattered patches to a few large concentrations of the target invasive plant. Treatments can reduce interference with recreation by focusing on large concentrations of target invasives that mat on the surface or smaller patches that impede surface water use in strategic locations. Also, treatments can reduce the risk of spread by focusing on public access sites or heavily used travel routes.
  5. Does the proposed treatment minimize potential negative impacts to aquatic habitat, including water quality?
  6. If the proposed treatment includes near shore areas (within 150 feet of shore), are these near shore areas included in the application for an IAPMP for reasons described in #4 above and not just to provide a landowner access to the lake?
  7. If the proposed treatment of invasive aquatic plants, when combined with all other treatment on the lake, does not exceed the limits on the littoral area allowed for treatment [see below], then stop here. If the proposed treatment results in control that exceeds the limits, then go to 8.
    • The limit on littoral area allowed for treatment with herbicide is 15% and the limit for mechanical treatment is 50%. The limit on the littoral area allowed for both herbicide and mechanical treatment combined is 50%. These limits are cumulative and include all permitted aquatic plant management activities on the lake.
  8. If the proposed treatment exceeds the limits described above, is there an active Lake Vegetation Management Plan (LVMP) that authorizes a variance from the littoral zone limits described above?
  9. If yes to 8, is the proposed treatment consistent with the active LVMP?
  10. If no to 8 - there is no active LVMP - what is the justification for the proposed treatment?
    • Review of the proposed treatment usually requires that results of a recent Point-Intercept survey be available to the DNR so that the distribution and composition of the plant community can be considered. Also, the DNR will consider water clarity as indicated by Secchi disk depth and other water quality data, which usually are available through LakeFinder. Below are additional factors to be considered.

Eurasian watermilfoil - Proposed applications of herbicide to more than 15% of the littoral area

In review of such proposals, the principle determining factors that the DNR will consider are:

  1. water clarity and
  2. distribution and composition of the plant community.

Water clarity is a major determining factor:

  • In lakes where clarity as indicated by Secchi depth is greater than 2m:
    • Proposal will be considered further
    • Consideration will also be given to the distribution and composition of the plant community.
    • Justification-lake-wide reduction in Eurasian watermilfoil has been shown to be followed by an increase in native plants.
  • In lakes where clarity as indicated by Secchi depth is 2m or less:
    • Consideration will also be given to the distribution and composition of the plant community.
    • Proposer likely will be directed to develop an approach to management that involves application of herbicide to no more than 15% of the littoral area.
    • Justification - there is significant risk that lake-wide reduction in Eurasian watermilfoil may not be followed by an increase in native plants and water quality maybe reduced.

Curly-leaf pondweed - Proposed applications of herbicide to more than 15% of the littoral area

Research and monitoring over the past ten years has shown that the most successful (meeting project goals and costs) projects done to control curly-leaf pondweed are those that involve application of herbicide to less than 15% of the littoral area.

  • Proposed applications of herbicide to more than 15% of the littoral area may be supported if the proposals include:
    • evaluation including monitoring by applicant or third party (other than the commercial herbicide applicator for the project) of
    • unique control treatments (e.g. alum, carp removal, or drawdowns)
  • Justification - There has been a focus over the last ten years on research and monitoring of herbicide treatment to control curly-leaf pondweed. These projects indicate that this method has been less effective especially on low clarity lakes. Specifically, treatments did not lead to an increase in water clarity. Although lake-wide reductions in curly-leaf were obtained, matching increases in native plants were not observed. Lake-wide control of curly-leaf pondweed in most cases appears to move in the direction of reducing the amount of vegetation in low clarity or eutrophic lakes.
    • Nevertheless, there is little information available on control of curly-leaf pondweed in combination with other management actions, such as drawdown, application of alum, removal of common carp, etc. Applicants who propose to explore these techniques further and who are able to monitor outcomes will provide needed information to lake managers.

Awarding grants to support costs of managing infestations of invasive aquatic plants

DNR staff will use the following criteria to evaluate applications and award grants. A successful application will receive a "yes" to all the questions below.

  1. Has the application for grant support been received and completed properly?
  2. Has the DNR approved an estimated acreage to be permitted in 2013 or issued an IAPMP to the applicant seeking grant support?
  3. Is there grant money available to support the control?

Grant Programs

References on management of aquatic plants

The document linked below contains links to a few selected references on management of aquatic plants, with an emphasis on invasive aquatic plants. The references listed tend to be somewhat technical and perhaps present more information than some readers will want. For others, these documents may be a starting point for more reading and research.

Past Stakeholder Engagement

The DNR is engaging stakeholders to help us improve management of invasive aquatic plants. This effort includes two distinct phases to date. Phase I, which took place early in 2011, gave citizens opportunities to express their concerns and suggest actions to the DNR related to aquatic invasive plant management. The goal of Phase II is to work with stakeholders to develop recommendations for possible revisions to Minnesota's approach to management of invasive aquatic plants. Phase II began with a meeting on September 22, 2011 (see Phase II - Results and Feedback below). This was followed in October by DNR Responses to Stakeholders. On November 2, 2011 a second meeting took place. Related documents are available below:

Phase I

Phase II


Contact Information

Chip Welling, Aquatic Invasive Species Management Coordinator
chip.welling@state.mn.us
500 Lafayette Rd, Box 25
St Paul, MN 55155-4025
tel. 651-259-5149

MN DNR Invasive Species Program Contacts