One thing is sure, we have to do something. We have to do the best we know at the moment. If it does not turn out right, we can modify it as we go along. Franklin Delano Roosevelt - President of the United States of America

Introduction

Control the weeds!Once these simple words are uttered at a lake or reservoir, controversy often soon follows. Why? Quarrels typically break out between and among user-groups, scientists, and management/regulatory agencies over whether there is a "weed problem" and whether the problem needs to be managed. If agreement is reached that management is necessary, quarrels then tend to erupt over how much aquatic vegetation should be controlled. If the level of vegetation management desired can be established, additional quarrels then develop over how to achieve desirable levels. Should nutrient control be instituted? Should aquatic herbicides be used or should mechanical harvesting be used? Should biological controls like grass carp be used? Should some combination of management techniques be used?

Faced with what seem to be unending questions and controversies, many individuals and agencies often choose the "Do Nothing" or "Delay" option. Doing nothing or delaying a decision are viable options when it comes to managing aquatic weed problems, but they are options that should not be chosen at the wrong time or for the wrong reasons. When nothing is done or delay occurs beyond a reasonable time because of fear of the unknown, powerful political forces may be unleashed. Soon "something" shall be done to solve the "problem" even if the political solution will create more problems at a later date.

Aquatic plant management is an important aspect of lake management. As with other lake management issues, controversies come with the territory. Quarreling amongst ourselves, however, cannot solve problems nor improve the chances that a serious aquatic weed problem will improve if left alone. A well-evaluated and carefully designed management plan must be developed for each water body. With reasonable care in the decision making process, aquatic plants can be managed successfully without destroying the desirable attributes of lakes and reservoirs that attract us to these water bodies.

Purpose of this manual

Many of the conflicts that arise over the management of aquatic plants in lakes and reservoirs are rooted in differences in educational background, philosophy, experience, and even differing regional perceptions of what is considered to be satisfactory aquatic plant management. This guidance manual is written to provide a better understanding of the concepts and techniques of aquatic plant management as well as the role of aquatic plants in lakes and reservoirs.

Emphasis is placed on the management of aquatic plants in lakes and reservoirs, but much of the information contained herein should also be useful to individuals concerned with the management of aquatic plants in ponds and flowing-water systems such as canals and rivers. The reader is provided information on all aquatic plant management options that are currently available for large-scale use, but mention is made of experimental techniques that seem to be ready for use. Most importantly, the pros and cons of using different techniques are discussed along with the potential trade-offs among alternative options given different lake uses.

The focus of this guidance manual is the management of aquatic macrophytes. Aquatic macrophytes, by definition, are the macroscopic (large enough to be observed by the naked eye) forms of aquatic plants found in water bodies. The term aquatic macrophytes, however, refers to a diverse group of aquatic and wetland plants and encompasses flowering vascular plants, mosses, ferns, and macroalgae. Although the control of microscopic plants commonly called algae or phytoplankton is discussed, the reader is referred to The Lake and Reservoir Restoration Guidance Manual or Restoration and Management of Lakes and Reservoirs (Olem and Flock 1990; Cooke et al. 1993) for more detailed information on the management of phytoplankton.

This guidance manual is not intended to serve as a stand-alone reference, but provides a scientific and technical basis for the development of workable aquatic plant management plans:

Chapter 2 discusses the history and development of aquatic weed control in the United States. Many of the conflicts associated with the development of aquatic plant management programs are rooted in the training and experience of the "experts." Understanding the different points of views of the experts or the different scientific paradigms that they espouse can be key to reaching consensus on how to manage plants in a particular water body.

Chapter 3 focuses on the influence aquatic macrophytes have on different physical, chemical, and biological processes in lakes and reservoirs. Understanding the role of aquatic macrophytes in water bodies, especially with regard to water quality and fisheries, is critical to the development of sound management plans. All readers are strongly urged to read Chapter 3 completely because this chapter reveals many relationships between aquatic plants and lake ecology that should be understood before developing an aquatic plant management plan.

Chapter 4 addresses the question of whether there is a weed problem at the lake or reservoir. This section focuses on how to define the problem and identify possible causes for the problem.

Chapter 5 discusses the various aquatic plant management techniques that are currently available for managing nuisance growths of aquatic weeds. Specific attention is focused on mechanical, chemical, and biological controls with discussion of the pros and cons of using these techniques. The full array of techniques are discussed even though some techniques are not legally available for use in certain regions (local agencies should always be consulted to document current laws and regulatory policy).

Chapter 6 focuses on how to develop a workable aquatic plant management plan. This chapter specifically addresses ecological, sociological, economic, and regulatory considerations. Techniques for conflict resolution are also discussed.

Chapter 7 provides some final comments regarding the future of aquatic plant management.

Audience

This manual is written for informed citizens and professionals in management/regulatory agencies who are interested in the management of aquatic plants in lakes and reservoirs. As with other technical supplements in this series, technical jargon has been kept to a minimum to help the reader grasp important points. Throughout the manual, words of importance are defined to eliminate the possibility of ambiguity. Some information is also repeated in the chapters to ensure that the reader will not miss important points by not reading the manual from cover to cover.

This manual provides general guidance on the management of aquatic and wetland plants in lakes and reservoirs. There, however, is an enormous amount of information available not only on aquatic plant management, but lake and reservoir management that can be very important when management plans are being developed for specific water bodies. Select references are therefore provided at the end of this manual to assist the reader with finding additional information. The reader, however, is strongly urged to consult local experts who are familiar with the water body of concern.

English units of measure are used where possible because this manual is intended to assist communication among diverse interest groups.

Finally, the North American Lake Management Society (NALMS) and the Aquatic Plant Management Society (APMS) recognize that citizens often hesitate to tread the territory staked out and vigorously (even viciously) defended by "experts." NALMS and APMS, however, encourage private citizens to take an active part in developing comprehensive lake management plans that include aquatic plant management plans. NALMS and APMS also urge professionals to work with citizens. Although working with a diverse group of nonprofessionals may be frustrating, experts by themselves can not manage lakes. We must all be part of the solution.