CHAPTER 12 - A Citizen's Manual for Developing Integrated Aquatic Vegetation Management Plans

The Integrated Approach—A Juggling Act

• The extent of problem plant(s) infestation
• Scale, intensity, and timing of treatment
• Effectiveness against target plant(s),
• Duration of control (short-term vs. long-term)
• Human health concerns
• Environmental impacts and mitigation, if needed
• Program costs
• Permit requirements (Federal, state, local).

• The type and extent of plant growth and timing of treatment.

In reviewing control options, it is important to understand both the extent and the life cycle of the problem plant species. What is the area of problem growth? If the infested area is small (say, 0.25 acre), then large-scale methods, like mechanical harvesting, would be inappropriate. The same is true for large-scale problems treated with small-scale methods. What is the plant's typical life cycle? Some plant species with early-season growth are more susceptible to treatment in the springtime. In other situations, winter treatment may be most effective.

• Probable duration of control.

How long will the plant be controlled? Is duration of control short-term (a month, a growing season) or longer term (one year, two years, more)?

• Site-specific constraints that might affect use of control method.

Does the site have a lot of submerged logs or bottom debris or water intake pipes that would hamper bottom treatments like rotovation or bottom barrier application? Are there many surface obstacles such as docks or buoyed areas that could interfere with surface operations of mechanical cutting or harvesting?

• Capital costs and operation/maintenance costs.

If specialized equipment is to be purchased for the control project, determine the cost of buying, operating and maintaining it, including staff wages and replacement costs.

Will the control option restrict use of the water body after treatment by banning water contact or ingestion (swimming, fishing, drinking or irrigation use)? Does the operation of large machinery or equipment occur at a peak time of recreational use? Does this control option represent a severe safety hazard or interfere significantly with normal use?

• Fisheries, waterfowl or wildlife status and general ecology of water body.

Does the aquatic system have important spawning sites? If so, control activities that disturb the bottom would be prohibited during certain critical periods. The presence of endangered, rare, or sensitive plants or animals utilizing aquatic plant beds could also limit the use of certain control methodologies.

• Balancing enhancement of beneficial uses with environmental protection.

What are the projected short-term and long-term impacts? Is there a risk that control for the sake of maximizing human use can seriously jeopardize an important segment of the native aquatic plant or animal community?

• Possible mitigation techniques and costs, including replacement of untargeted plants that are removed.

Some aquatic plant control techniques pose higher risks of removing non-target organisms, particularly emergent vegetation along the shoreline. Estimates should be made of the types and areas of plant species that may be affected by the control techniques. Lost areas can be mitigated by replanting with nursery stock plants or plants harvested from local areas (check on local harvesting restrictions). Volunteers can often help with revegetation efforts, if needed.

• Local, county, state or Federal permit requirements.

Find out what permits are necessary, whether a fee is required, and the expected time it takes to process the permit application(s). The length of time involved in processing different permit applications can vary enormously (See Table 12-1.). While most permits for aquatic plant control work in freshwater are free, some have an assessed fee (for example, a shoreline management permit has a cost that depends on the value of bottom barrier material applied).

Example Of Recommended Treatment Scenario

The following is an example of a recommended treatment scenario produced for Lake Tranquil : 

• Whole-lake diver surveillance for milfoil locations (spring).

• In-lake treatment

• First-year milfoil treatment: Systemic herbicide application in boat launch embayment with bottom barrier application in swimming areas (spring).
• Second-year milfoil treatment: Diver hand removal/bottom barrier application on residual populations (spring).
• Water lily treatment: Systemic herbicide/bottom barrier (Spring).

• Watershed controls.

You have come a long way in gathering critical information and evaluating plant control options with regard to the specifics of your water body and user needs. Now is a good time to update the community on the status of the emerging plan. The information can be presented to the community for discussion and approval through the public process. After obtaining group consensus on a treatment scenario, the steering committee can finalize the long-term action program.

Table 12.1. Who Permits What?

Permits/Documents Required for Aquatic Weed Control Activities in Washington

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