CHAPTER 10 - A Citizen's Manual for Developing Integrated Aquatic Vegetation Management Plans

A variety of methods are currently available for controlling nuisance aquatic plants. The following is a list of aquatic plant control alternatives currently available in the State of Washington:

Physical Methods

• Hand-pulling/cutting
• Bottom barrier application/ sediment covers
• Water-level drawdown
• Watershed controls
• Water column dyes

Mechanical Methods

• Harvesting and cutting
• Bottom tillage (rotovation)
• Diver-operated dredging

Biological Methods

• Grass Carp

Chemical Methods

• Fluridone
• Glyphosate
• Endothall
• Copper compounds

Control Alternatives Summarized

With so many techniques to choose from, how do you sort out the options? First, you'll have to become familiar with the advantages and disadvantages of each control alternative. Having a basic understanding of the capabilities of each option will help you choose the best combination of treatment methods.

More complete and in-depth information on these control methods is available from other sources. Appendix D of this manual describes each option's mode of action, effectiveness and duration of control, advantages, drawbacks, costs, and permits, and provides other comments. Factsheets on aquatic plant control methods are available from Ecology. Other references and resources are listed below in the Quick References section.

No action alternative: Aquatic plant management usually involves "doing something" in the water body to correct the problem. Sometimes, however, control options may not be as appealing as simply "doing nothing". It is important to consider possible consequences to the water body if no action is taken against problem aquatic plants. The choice of no action may have serious impacts on the aquatic ecosystem and related human uses when problem infestations are due to non-native, invasive species.

In particular, it's important to consider the potential for nuisance plants to alter habitat and impact aquatic organisms. Water quality effects should be evaluated. Dense weed beds can produce changes in the water's dissolved oxygen levels, temperature and pH that can be harmful to aquatic life. In addition to reducing recreational enjoyment, excessive weed growth could negatively affect tourism and even commercial activities associated with use of the water body.

In summary, before a decision is made to "do nothing" to control nuisance plants, the potential consequences of that decision on beneficial uses of a water body must be carefully considered.

References and Resources on Aquatic Plant Control Alternatives

• Aquatic Weeds Management Program Coordinator, Department of Ecology^A
• Aquatic Plant Management Program, FSEIS¹
• Restoration and Management of Lakes and Reservoirs¹³
• Lake and Reservoir Restoration Guidance Manual⁴
• Aquatic Plant Identification and Herbicide Use Guide, Vol II¹⁰

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