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Waterway and wetland permits: part III - management of aquatic plants and algae in ponds

What you need to know: application, registration and certification

In Wisconsin, a permit is required to use aquatic herbicides. A Permit Application for Chemical Aquatic Plant Control (Form 3200-4) can be obtained from your local DNR Service Center. All pesticides are required to be registered for use with both the U.S. Environmental Protection Agency (USEPA) and the Department of Agriculture, Trade and Consumer Protection (DATCP). In some cases, you may have to be certified as a pesticide applicator by DATCP in order to apply herbicides and/or algaecides. For instance, if the pond has a discharge that cannot be controlled to prevent chemical loss, or if there are two or more property owners on the pond you will need a certified applicator to apply chemicals.

Nearly all aquatic insecticides and piscicides are classified as restricted use products by DATCP and pesticide certification is required. These types of pesticides have a greater risk to potentially harm the environmental and/or affect human health. Therefore, it is recommended you consult with a professional pond management firm if you are going to use chemicals to control insects or fish. For more information about pesticide certification or restricted use pesticides, contact your county Extension agent [exit DNR] or the DATCP office [exit DNR].

Aquatic herbicides

There are six families of aquatic herbicides registered for use in Wisconsin. These products, sold under a variety of trade names, are described in Table 2. For a more comprehensive description of a particular compound, contact the nearest DNR Service Center and request a Chemical Fact Sheet.

Table 2: Aquatic Herbicides Approved for Use in Wisconsin
Chemical (trade names) Management summary Management implications
Copper Compounds (a variety of products with a multitude of trade names) Broad spectrum algaecides used to control both planktonic and filamentous algae. No weekly carryover benefits. Non-selective and will kill algae within 72 hours. Some algae are resistant. Algae can return within 10 days.
Diquat Dibromide (Reward®, Diquat) Broad spectrum, contact herbicides that are effective on submersed aquatic plants. No carryover benefits. Non-selective and will kill plants within 10-14 days. Not effective in turbid waters. Consumption restrictions apply.
Endothal Acid (Aquathol®, Hydrothol®) Broad spectrum, contact herbicides that are effective on many submersed aquatic plants. No carryover benefits. Non-selective and will kill plants within 10-14 days. Fish consumption, drinking, and irrigation restrictions apply.
Glyphosate (Rodeo®) Broad spectrum and systemic (will kill roots). Herbicides used with a surfactant to control emergent and floating plants. Non-selective and requires the use of a surfactant to ensure uptake by plants. Most commonly used for control of purple loosestrife.
2,4-D (Aquakleen, Aquacide, Navigate®, Weedtrine, among others) Controls only dicotyledons (broad leaf plants such as water lilies, watershield, and water milfoil) with some potential for multiple year control. Does not control the majority of aquatic plant species found in WI. Commonly used for control of Eurasian water milfoil. Drinking and irrigation restrictions apply.
Fluridone (Sonar®) Broad spectrum herbicide that may be dosed selectively for some plants. May have some multiple year control. Very water soluble and works best when entire pond is treated. Kills plants slowly (20-60 days). Most useful for duckweed control. Irrigation restrictions apply.

It is illegal to apply products to ponds that are not registered for use in aquatic environments. Non-registered chemicals may pose severe human health risks, contaminate groundwater or kill non-target fish and wildlife. Do not use swimming pool chemicals, home brews or agricultural pesticides not listed in Table 2. For example, Simazine was formerly labeled for use in lakes and ponds, but because of drinking well contamination problems, it is no longer registered for use in surface waters.

You will be required to prevent outflow from your pond during pesticide application and for the duration of the water use restriction listed for the product. Prior to purchasing or applying a pesticide, review the label and the Material Specification and Data Sheet (MSDS). Both of these will provide important information regarding safe handling and application of the product.

Remember, registration of a chemical with USEPA and the DATCP does not mean the product is safe, rather it means that there is an acceptable risk associated with proper use of the product.

Spraying Aquatic Herbicide

The use of aquatic herbicides may not be the best option to achieve long-term results. Herbicides do not control the nutrients that are the main cause of excessive aquatic plant growth; therefore, plants will continue to grow year after year. Herbicides are selective for specific types of plants so it is important to identify the aquatic plants in your pond before treating. Random application of herbicides without consideration of the type of nuisance plants often results in ineffective treatment and the addition of unnecessary pesticides to the environment. Chemical treatment of plants can also result in excessive algae growth. Learn about water use restrictions and the potential negative impacts to other organisms in your pond before using chemical treatments. When using aquatic herbicides remember that more is not better. More can actually prevent the product from performing in the intended way. Always follow label instructions and use the required protection gear. More information can be obtained from your local DATCP office [exit DNR].

Water quality monitoring

Water quality monitoring of your pond is a very important component of pond management and is always worth the investment. Pond owners may work with a pond consultant to develop a water quality monitoring plan or even enlist help from a local high school or nearby university. There are numerous references on the Internet or in publication that can help you develop a plan for, and understand the results of, your water quality monitoring. The UW-Extension publication "Understanding Lake Data", #G3582 [exit DNR] is a good place to start.

At a minimum, pond owners should plan to analyze water quality of their pond in the spring and again in August. There are literally thousands of chemical components or biological characteristics that can be monitored in your pond. A basic water quality monitoring program will include the following components:

Dissolved Oxygen   Temperature
pH   Alkalinity
Total Phosphorus   Nitrate plus Nitrate
Ammonium   Organic Nitrogen

Putting it all together

After you have set the objective for how you want to use your pond or how you want your pond to look, you should identify the limiting factors that are preventing you from reaching those objectives. These limiting factors can range from inadequate depth for fish survival to a poor plant community for wildlife. One of the most common limiting factors is excessive nutrients that cause nuisance growth of aquatic plants and algae.

Once you have identified the limiting factors, review the various tools available and develop a management plan. Typically this plan will integrate a variety of management tools to achieve your objectives for your pond. Investigate the local and state permit approvals, the cost of implementation and management, and the guaranteed effectiveness of your plan. It is usually very helpful to bring in a professional environmental pond management firm during this process. You can find pond management firms in the phone book, through advertisements in local papers and on the intranet. There is also a listing of lake and pond service companies [exit DNR] available from the UW-Extension.

After you have developed your pond management plan, acquired all necessary permits and approvals, and arranged for any professional services, it is time to implement the plan. Remember to monitor the effectiveness of you management plan. It may be necessary to redefine your objectives for the pond if the natural characteristics, permitting restrictions, or financial costs prevent you from being able to reach your objectives. In summary, careful planning in concert with realistic expectations will allow you to enjoy the benefits for years to come.

Water is a magnet to life. Having a pond on your property can bring years of enjoyment as you provide a haven for wildlife and place for you to discover and enjoy the little splendors of the natural world. Careful planning and realistic expectations will allow you to enjoy the benefits of your pond for years to come.

Still PONDering what to do?

In this short document, there is no way we can address all of the components of pond management. Contact a professional consultant or your local DNR Service Center and request one or more of the publications listed below.

Reference material for pond management

Contact a professional consultant or your local DNR Service Center to request one or more of the following publications:

  • Aquatic Chemical Fact Sheets
    • Copper Compounds, PUBL-WR-238
    • Diquat, PUBL-WR-235
    • Endothall, PUBL-WR-237
    • Fluridone, PUBL-WR-240
    • Glyphosate, PUBL-WR-239
    • 2,4-D, PUBL-WR-236
  • Aquatic Plant Management and Protection Fact Sheets
    • Algae That Produce Toxins and Their Potential Effects, PUBL-WR-162-87
    • Aquatic Plant Cutting and Harvesting Businesses, WDNR Tech Bulletin 156
    • Aquatic Plant Screen, PUBL-WR-202-88
    • Do You Need A Mechanical Aquatic Plant Harvester? Machine Harvesting of Aquatic Plants, PUBL-WR-201-88
    • Managing Your Aquatic Plant Harvesting Program, PUBL
    • Non-Mechanical Methods of Aquatic Plant Harvesting, PUBL-WR-204-88
    • Swimmers Itch, PUBL-WR-170-87
    • The Facts... On Eurasian Water Milfoil, PUBL-WR-462-96-REV
    • Through the Looking Glass, A Guide to Wisconsin's Aquatic Plants, PUBL-FH-207-97
    • Wisconsin's Aquatic Plant Management and Protection Program, PUBL-WR-448-96
    • What to Do With Harvested Aquatic Plants, PUBL-WR-203-88
  • DNR Water Regulation and Zoning Pond Planner Fact Sheets
    • Wisconsin Water Regulation Programs Work for You, PUBL-WZ-WZ002
    • Building Near Wetlands, PUBL-WZ-WZ021-91
    • Pond Planner, PUBL-WZ-012-94-REV
    • Wildlife Pond Diagram, PUBL
  • DNR Applications for Permits or Approvals and Administrative Codes
  • Pesticide Certification
    • Applicator Training Manual, UW-Extension, 1575 Linden Drive, Madison, WI 53706
    • Pesticide Certification, DATCP, 2811 Agriculture Drive, Madison, WI 53704
  • Buffer Zones
    • Shoreline Plants and Landscaping, County Extension, GWQ014
    • Tree Planting in Wisconsin, PUBL-FR-001
    • What is a Shoreland Buffer Zone?, PUBL-WR-169-87
  • Lake and Pond Management
    • Ponds in Connecticut. A guide to planning, design and management. Available from: Connecticut Department of Environmental Protection, Hartford, CT.
    • How to Identify and Control Water Weeds and Algae. Available from: Marine Biochemists, Milwaukee, WI.
    • Lake Smarts, The First Lake Maintenance Handbook. Available from: Terene Institute, Washington, D.C.
    • Diet for a Small Lake. Available from: NY Dept. of Environmental Conservation, Albany, NY.
    • Restoration and Management of Lakes and Reservoirs. 2nd ed. CRC Press. Boco Raton, FL.
  • Consultants and Services
    • The Lake List [exit DNR], UW-Extension Lakes Program, College of Natural Resources, UW-Stevens Point, Stevens Point, WI 54481

  • Internet

Back to Part I | Back to Part II

Last revised: Thursday October 31 2013