Guide for Developing 

Integrated Aquatic Vegetation Management

Plans in Oregon

Maribeth V. Gibbons, Mark G. Rosenkranz

Harry L. Gibbons, Jr, Mark D. Sytsma

Illustrations by Ruth Gothenquist

Plant drawings by IFAS Center for Aquatic Plants

and Wisconsin Lakes Partnership

1999

Center for Lakes and Reservoirs • Portland State University • Portland OR 97207
Acknowledgements

This manual benefited tremendously from the review and comments of many people. We thank Jim

Brown, City of Lakeside; Avis Newell, Oregon Department of Environmental Quality; Ralph Rogers and

Jannine Jennings, US Environmental Protection Agency; Roseann Kachadoorian and Dennis Isaacson,

Oregon Department of Agriculture; Thomas Savidge, US Army Corps of Engineers; Gail McEwen and

Gregory Robart, Oregon Department of Fish and Wildlife; Dana Field, Oregon Division of State Lands;

Dick Pellissier, Smith Lake Improvement, Inc.; and Ken Bierly and Vivienne Torgeson, Oregon

Watershed Enhancement Board.

This project was funded by the Governor’s Watershed Enhancement Board

IAVMP Manual

i v.10/99
v.10/99

IAVMP Manual 

ii

Table of Contents

Preface

Material covered in this manual

A quick walk through this manual

Part I: Introduction to Aquatic Plant Management

Chapter 1, Introduction

Does your water body have an aquatic plant or an algae problem?

What is an integrated aquatic vegetation management plan?

When is an IAVMP required?

Part II: Developing a Plan

Chapter 2, Getting started

Organization is key

The steering committee

Planning steps summarized

Chapter 3, Develop a problem statement (Step A)

What is the problem?

How to write a clear problem statement

Example of a problem statement

Chapter 4, Identify management goals (Step B)

Setting aquatic plant management goals

Goal setting criteria

Example of aquatic plant management goals

Chapter 5, Involve the public (Step C)

The importance of public involvement

Public involvement steps

Chapter 6, Identify water body/watershed features (Step D)

Water body-watershed connection

How to describe the watershed and water body

Getting started in your search of the water body

Sampling/monitoring to fill data gaps

Chapter 7, Identify beneficial use areas (Step E)

How to determine beneficial use areas of your water body

Example of a water body usage map
v.10/99

IAVMP Manual

iii

Chapter 8, Map and characterize aquatic plants (Step F)

What is an aquatic plant survey?

How to map aquatic plants

Example of aquatic plant map

Example of written description characterizing aquatic plants

Chapter 9, Investigate control alternatives (Step G)

Control alternatives available in Oregon

Control alternatives summarized

Chapter 10, Specify control intensity (Step H)

What are the different levels of control?

How to determine levels of control in the water body

Example of a control intensity map

Chapter 11, Choose integrated treatment scenario (Step I)

The integrated approach

A procedure for choosing an appropriate treatment scenario

Example of recommended treatment scenario

Chapter 12, Develop an action program (Step J)

Putting all the pieces together

Components of the action plan

Part III: Implementing a Plan

Chapter 13, I have a plan–What’s next?

Permits and other requirements

Implementation needs management

Monitoring program effectiveness

Keeping everyone informed

Part IV: Technical References

Appendix A – Glossary of terms

Appendix B – Invasive, non-native aquatic plant fact sheets (Illustrated)

Appendix C – Watershed and limnological background information

Appendix D – Aquatic plant control methods

Appendix E – Resources and references
v.10/99

IAVMP Manual 

iv

Preface

T

he ecological relationships in our lakes, ponds and streams have resulted from of a long, continuous process of geologic change and biological evolution. As systems have evolved, communities

of aquatic plants and animals developed that are uniquely adapted to environmental conditions of

each system. The native aquatic plant communities that are integral to aquatic ecosystems provide food,

shelter, and nesting sites for many kinds of fish, waterfowl and smaller animals. Rooted aquatic plants

help secure and stabilize shorelines and play a major role in the cycling of nutrients, particularly nitrogen

and phosphorus, in aquatic ecosystems. In some cases, large aquatic plants help improve lake water

clarity by competing for nutrients with small (typically microscopic) aquatic plants, called algae, which

can form nuisance “blooms” when excessive nutrients are present. Invasion of a system by a non-native

aquatic plant species, however, can quickly destroy the lake community that took so many years to

develop. 

Aquatic weeds such as Eurasian watermilfoil, Parrotfeather, and Brazilian elodea, have invaded many of

Oregon’s lakes, reservoirs and streams. These invasive plants have spread quickly in the absence of diseases, insects, and other environmental constraints that serve as natural controls in their native regions.

Aquatic weeds have damaged the function and health of our aquatic ecosystems and degraded beneficial

uses (recreational, aesthetic enjoyment, fishery, irrigation, water supply, wildlife habitat, etc.). They raise

pH when they photosynthesize, deplete dissolved oxygen when they die, and alter the structure of the

aquatic ecosystem. They slow water movement, increase sedimentation rates, and accelerate filling-in of

lakes and reservoirs. Aquatic weeds often interfere with human use and enjoyment of a waterbody as

well. They clog propellers, snag fishing lines, and are a danger to swimmers and skiers who become

entangled in dense vegetation. Aquatic weeds block flow in irrigation and drainage systems and clog

water intake screens used for agriculture. 

Aquatic weeds often form thick, single-species stands that can seriously damage the spawning and rearing habitat of salmon and other fish. Since preservation and restoration of salmon habitat is a critical

issue in Oregon, invasive aquatic plants that affect their habitat must be responsibly managed (See

Appendix C-Watershed and Limnological Background Information).

Nuisance Native Aquatic Vegetation

This planning document focuses on management of non-native plant species in Oregon waters.

Under certain conditions, however, native aquatic plants can become a problem too. Causes of

abundant growth of native vegetation can be complex. Luxuriant growth often signals excessive

nutrient concentrations in the lake. High nutrient concentrations may originate in the lake itself

(internal loading), or from around the lake or elsewhere in the watershed (external loading). Such

water quality problems require intensive management approaches that may differ from those

needed to eliminate non-native plant invaders from a waterbody. Furthermore, management goals

for nuisance native plants emphasize reduction of problem growth, not elimination of the species

from the system, as may be required for non-native weed control.
IAVMP Manual 

v

Preface

v.10/99

Invasive aquatic vegetation can be managed, and in some cases native vegetation can be restored, with a

well-planned management program that balances biological, social, environmental and site constraints.

Finding a remedy to nuisance aquatic plants that is effective, environmentally sensitive, and economically feasible is the goal of integrated aquatic vegetation management.

This manual is a guide to the steps needed to produce an integrated aquatic vegetation management plan

(hereafter called the Plan). Using an integrated management approach, citizens and organizations can

work together with a watershed council, special district, or

other group to produce a management plan to combat a weed infestation in a lake or reservoir.

The process described in this manual thus 

represents a major step toward holistic 

(lake and watershed) management of aquatic

plants in freshwaters of Oregon.

Material Covered In This Manual

By definition, integrated aquatic vegetation management requires incorporating information on many

aspects of a waterbody and its watershed into a unique planning document. The challenge in preparing

this manual was in condensing a wealth of critical information on the topic into a comprehensive but

simple format. It is a step-by-step guide, as the process of planning is broken down into separate but

interrelated steps. This manual is designed to cover a wide range of situations that might be encountered

while managing aquatic plants in Oregon’s public lakes, although the principles and procedures can also

be applied to private waters. While the document does refer to scientific principles when needed, it is not

a primer on limnology or lake management. Appropriate references, resources, and a contact list for technical assistance from local, state and federal agencies are provided.

This manual does the following:

• describes how to identify six invasive, non-native aquatic plants found in Oregon waters

• provides an understanding of aquatic vegetation functions in aquatic ecosystems

• explains methodology and appropriate use of various aquatic vegetation management techniques

• identifies constraints affecting application of aquatic vegetation management activities

(e.g., salmon habitat, use as a drinking water supply)

• offers guidance on mapping vegetation and collecting water samples

• defines and explains technical terms

• provides step by step guidelines on how to prepare a plan

Terminology

Many descriptive terms have been used for problem aquatic plants. They have been called invasive, nuisance, noxious, exotic, alien, non-native, and non-indigenous. More colorful colloquialisms include grass, sea weeds, moss, and frog moss. This manual deals primarily with aquatic

plants that degrade beneficial uses of aquatic systems, and which have been introduced to

Oregon by human activities. Throughout the manual, these plants will be referred to simply as

aquatic weeds.
IAVMP Manual 

vi

Preface

v.10/99

A Quick Walk Through The Manual

This manual is divided into four parts:

PART I: Introduction ToAquatic Plant Management

• Chapter 1, Introduction. This chapter defines the Plan and 

presents the purpose and objectives of these Plans.

PART II: Developing A Plan

• Chapters 2-12, Steps in the Planning Process. Using flow

diagrams and illustrations, these chapters give step-by-step

instructions for putting together a Plan.

PART III: Implementing A Plan

• Chapter 13, I Have a Plan—What’s Next? In this chapter,

the reader is offered guidance on how to use a Plan.

PART IV: Technical References

• Appendix A– Glossary of Terms–defines technical terms used in aquatic plant management.

• Appendix B– Invasive, Non-native Aquatic Plant Fact Sheets–provides drawings, and features of 

non-native (exotic) aquatic plant species that are or could be a threat in Oregon waters.

• Appendix C– Watershed and Limnological Background Information–briefly describes physical, 

chemical and biological features of a water body and its watershed.

• Appendix D– Aquatic Plant Control Methods–summarizes aquatic plant control methods available 

for Oregon waters.

• Appendix E– Resources and References–presents a list of resource agencies and organizations 

that can provide technical information and assistance on aquatic plant management in Oregon. It 

also lists technical reference materials that provide more detailed coverage of topics discussed in 

this manual.

Throughout the manual, you will also find the following special notations:

RED FLAG: These alert the reader to the presence of a serious situation in the waterbody 

requiring immediate or special action as part of the planning process.

TIP: These give extra information on important points or directions for particular tasks.

These point out areas where you may need to revisit steps already taken after ! gathering new information.

References and Resources:

• These appear at the end of each chapter and list names of agencies, organizations, and titles of literature that can provide more information on topics just discussed. Citations in the quick reference sections and text are numbered to correspond to the references, or lettered to correspond with the 

resources, appearing in Appendix E.
Blank IAVMP Manual

NOTES:
1-1

IAVMP Manual 

v.10/99

Aquatic Plants and Algae

Aquatic plants are large vascular plants that live in wet conditions. Aquatic plants (also called

macrophytes) usually possess true roots, stems and leaves, and look like plants in your yard. T h e y

can be grouped into four types: emergent plants, rooted floating-leafed plants, submersed plants,

and free-floating plants. 

Emergent plants have a large portion of stems and leaves growing above (emerging from) the

water surface; they are found in shallow water (less than 2 feet deep) or along the shoreline.

Rooted floating-leafed plants have leaves that float on or just above the surface but are connected to the bottom by long, tough stalks. 

Submersed plants have most of their leaves and stems below the water surface, often with flowering parts projecting above surface. They may be securely or loosely rooted in the bottom. 

Free-floating plants float near the water surface with root systems dangling in the water, but not

connected to the sediment. 

A l g a e are simple, primitive plants that do not have true roots, stems or leaves. Many algal species

are microscopic forms that float in the water (called phytoplankton). Some appear as large, easily

seen upright forms, and are called macro-algae. Certain types of green algae can form stringy

colonies 3 feet or more in length. Nuisance algal growth commonly associated with nutrient problems often appears in the form of surface scums that are greenish or brownish in color.

Algae and free–floating plants get their nutrients from the water while rooted plants get their

nutrients from the sediment. Reducing excess nutrient inputs will have minimal impacts on

rooted vegetation and may increase the growth of light-limited rooted plants.

INTRODUCTION

CHAPTER 1

beneficial uses. The biology and ecology of weeds

allows them to fluorish under a wide range of conditions. Nutrient enrichment is not a prerequisite

for aquatic weed problems. Often, all that is needed is to introduce an invasive species to a system.

Invasive weed species–Eurasian watermilfoil, and

Brazilian elodea for example–are listed as Noxious

Aquatic Plants by the State of Oregon (See Box

next page). Managinßg aquatic plant problems, particularly those resulting from non-native species

infestations, should follow the integrated aquatic

vegetation planning route described by this manual. 

Does Your Waterbody Have 

An Invasive Aquatic Plant Or 

An Algae Problem?

This manual focuses on controlling nuisance

aquatic plants, occurring in Oregon lakes. To use

this manual, it is necessary to distinguish between

an aquatic plant problem, and a water quality

enrichment problem that typically results in excessive algae production (See Box this page).

The most serious type of aquatic plant problem is

caused by invasion of a waterbody by a non-native

species. Non-native weed invaders may flourish in

suitable conditions and degrade habitat and other
Chapter 1 IAVMP Manual

v.10/99

Unlike noxious aquatic weed problems, algal blooms

and luxuriant growth of native plant species may be

caused by nutrient enrichment. 

Management approaches and techniques dealing

with nutrient enrichment in lakes can differ greatly

from those described in this document. While the

planning process outlined in this manual can be

applied to managing excessive growth of native

species in a waterbody with nutrient enrichment

problems, other management measures are usually

needed (e . g., identification of nutrient sources, limiting excessive nutrient inputs by using best management practices (BMP) in the watershed, specific inlake restoration measures).

Identification of the amount of nutrient input that a

lake or reservoir can sustainably receive requires significant analysis of nutrient budgets and lake

processes. When a lake exceeds Oregon water quality standards, the state must develop a To t a l

Maximum Daily Load (TMDL). Development of

TMDLs for lakes requires intensive sampling and

often includes a modeling effort, which is beyond the

scope of this document. Contact the Oregon

Department of Environmental Qualify for more

information on T M D L development for lakes in

O r e g o n .

What Is An Integrated A q u a t i c

Vegetation Management Plan?

Designing a cost-effective and environmentally

sound aquatic plant management program is a challenge. Identification of lake uses is fundamentally

important because management options for diff e r e n t

uses may be incompatible. Amanagement plan for a

drinking water reservoir, for example, will likely differ from one developed for a flood control reservoir.

Choosing the appropriate course of action in the

face of competing interests and solutions is the

ultimate goal of a management plan. A number of

control methods for aquatic plants (physical,

mechanical, chemical, and biological) are available. Like the noxious plants themselves, all management activities have potential negative environmental impacts. They also vary widely in cost and

effectiveness. 

Pulling together all the interests around a lake, and

getting them to agree on a course of action can be

contentious and trying at times. Mapping a course

of action can be made easier by careful development of an integrated aquatic vegetation management plan (the Plan). The Plan provides a means to

make informed decisions for managing aquatic

weeds that protect human health and the environment. It also assures that aquatic plant management is consistent with other management plans

affecting the waterbody, such as watershed management or shoreline management addressed in

local, County, or State plans (e.g., the Oregon Plan

for Salmon and Watersheds–See Box next page).

A Plan must consider such concerns as:

• How bad is the aquatic plant problem?

• At what level will plants become harmful and 

when should action be taken to control them?

• When is the best time of year to kill, remove, or 

suppress the nuisance plant species?

• What methods will best deal with the target 

weed species, and for how long?

• How will the treatment affect humans, native 

plants, and wildlife?

• Are control costs reasonable and affordable?

• What modifications in management strategies 

will be needed as nuisance plant conditions 

change over time.

1-2

Fresh Water Aquatic Noxious Weed Species in Oregon

Common Name Scientific Name Growth Habit

Eurasian watermilfoil Myriophyllum spicatum submersed

Smooth cordgrass Spartina alterniflora emergent

Brazilian elodea Egeria densa submersed

Hydrilla Hydrilla verticillata submersed

Purple loosestrife Lythrum salicaria emergent
When Is A Plan Required?

An integrated aquatic vegetation management plan

(IAVMP) is necessary to deal with nuisance (especially noxious, non-native) aquatic plants in lakes,

ponds, or rivers. This is particularly important

given the multiple uses of our lakes and streams

and the potential widespread negative impacts

these invaders can have on health and usage of an

aquatic system.

Plans may be required before certain aquatic plant

control activities may be initiated. For example, in

sensitive salmonid-bearing waters described in the

Oregon Plan for Salmon and Watersheds, a plan

should be completed that addresses the multiple

objectives of controlling nuisance plants and protecting other aquatic species

Balancing Act

Consideration of site-specific factors is necessary

when choosing management methods for a specific

waterbody. There is no magic bullet. For example,

no method exists that can completely remove an

exotic species infestation and at the same time be

inexpensive and have no effect on the local ecology. Thus, the planning process should carefully

balance all these concerns to develop a plan that

meets the needs of the community while preserving the health of the ecosystem.

Adaptive Document

The Plan should be flexible and allow for change.

An adaptive document provides for modification of

the Plan in response to new information or changing circumstances. Factors that could affect the

Plan include changes in the aquatic plant problem,

water use priorities, and watershed activities that

influence aquatic plant growth. Also, plant control

technologies as well as government policies and

regulations may change over time and affect the

Plan.

Taking the Long View

Aquatic plant management is a long-term venture;

achieving management goals for a waterbody can

take many years. Even after main goals are

attained, some form of management, if only 

minimal, may be necessary to maintain desired

aquatic plant conditions, or to prevent re-occurrence of non-native weed species.

TIP: Aquatic vegetation management plans for 

other lakes may be available to use as models while you write your own plan. Please 

contact Mark Sytsma, PSU Center for Lakes 

and ReservoirsJ. For a listing of Oregon lake 

assciations, contact Oregon Lakes 

Association (OLA) H

IAVMP Manual Chapter 1

v.10/99 1-3

A Look At The Oregon Plan for

Salmon and Watersheds

Initiated in 1995, Oregon’s salmon restoration

initiative is designed to restore salmon to a

level at which they can once again be a part

of people’s lives. While the Oregon Plan

focuses on the needs of salmon and steelhead, it will conserve and restore crucial elements of natural systems that support fish,

wildlife and people.

Government alone cannot conserve and

restore salmon and steelhead, so the plan

recognizes that conservation efforts must be

worked out by communities and landowners

in the form of watershed councils, soil and

water conservation districts and other grassroots efforts.

In brief, the Oregon Plan involves the following: (1) coordination of effort by all agencies,

(2) development of action plans with relevance and ownership at the local level, (3)

monitoring progress of conservation and

restoration efforts, (4) making appropriate

corrective changes in the future and (5)

implementing measures focused on salmon

recovery and watershed health.

See: www.oregon-plan.org
IAVMP Manual

NOTES:
Organization Is Key

You are probably reading this manual because you

are concerned about an invasive or nuisance aquatic

plant problem in your favorite lake or river. Others

may share your concern. The first step in managing

aquatic plants is to get organized. Begin by talking

with your neighbors to determine if they have similar concerns about your waterbody.

The next step is to gather together a core group to

talk more about the problem. The gathering might

be an informal one, such as a potluck picnic or

barbecue, where concerns about aquatic plant

problems can be discussed at more length.

Important questions that will need to be considered

include:

• Is there an aquatic plant problem?

• What is the problem?

• Should anything be done about it?

• Should a community group be formed to address

the problem?

• Who will participate in the planning process?

The core group can then plan to meet with the

larger lake community to share their concerns in

a more formal setting. The local

watershed council can be key

to any aquatic weed control program that may be

implemented. The

watershed council has

representatives of various user groups in the

watershed that need to be

involved in the decision making

process. Posting a notice on the community bulletin-board or in a newsletter, or sending

out a one-page flier are simple ways to notify the

neighborhood of the location and intent of such a

gathering. Often, newspapers are willing to publish

a short article for folks organizing neighborhood

meetings.

The Steering Committee

The local watershed council can establish a special

steering committee headed by one or two key individuals. Throughout the planning process, the

steering committee should represent the larger

community of lake residents, as well as those with

management responsibilities and interests in the

lake. This group will be responsible for completing

the steps in this manual to produce a plan that will

utimately be presented for approval to the watershed council or other relevent body. Thus, it will

be important for the steering committee to remain

in touch with the lake community and watershed

council to share information and allow for participation of all interested individuals in the planning

process. This contact can occur through newsletters

or scheduled committee meetings or general meetings open to the public.

To begin the process of “learning more about it,”

the steering committee should identify the problem

and start to assemble available background information on the topic of aquatic plant management. 

A first point of contact for existing lake information should be with the local watershed council, the Oregon Departments of Fish

and Wildlife, and the Department

of Environmental Quality, which

may have watershed or lake

data reports available. Past

studies or reports can be useful, such as diagnostic investigations called “Phase I” studies,

reconnaissance lake data reports,

and summaries such as found in the

Atlas of Oregon Lakes. These reports usually

include an aerial photo and depth contour map of

the waterbody.

IAVMP Manual 

v.10/99 2-1

CHAPTER 2

GETTING STARTED
Planning Steps Summarized

Supplied with background information, the steering committee should begin to assess the aquatic

plant problem and the need for action by completing the steps described in Chapters 3-12 of this

manual.

The diagram on the following page illustrates the

steps needed to complete the Plan. The diagram

begins at the upper left-hand corner with the Lake

Steering Committee. The planning process consists

of two phases:

• Phase I (Problem/Site characterization) 

• Phase II (Control Strategies Development)

Phase I involves collecting information about

aquatic plants and other features of your project

area. The right side of the diagram presents the

steps of Phase I:

• Develop Problem Statement (STEPA)

This step involves developing a realistic problem statement describing limitations on 

beneficial uses of the waterbody.

• Identify Management Goals (STEPB)

This step identifies reasonable aquatic plant

management goals that maximize beneficial 

uses yet are compatible with the waterbody’s

capacity to sustain the uses.

• Involve the Public (STEP C)

This step offers guidance in bringing the community into the planning process.

• Identify Waterbody/Watershed Features

(STEP D)

This step investigates background features of

the waterbody and watershed to understand

the whole system.

• Identify Beneficial Use Areas (STEP E)

This step focuses on identifying beneficial use 

areas of the waterbody in a waterbody Use Map.

• Map and Characterize Aquatic Plants

(STEP F)

This step outlines how to perform an aquatic

plant survey to identify and map general plant 

types in a waterbody. This step also includes 

translating survey data into a description of 

beneficial and problem plant zones in a water 

body.

The left side of the diagram depicts Phase II,

which investigates aquatic plant control strategies

and applies Phase I results to fine-tune a specific

plan through the following steps:

• Investigate Control Alternatives 

(STEP G)

This step investigates available control options 

in terms of effectiveness, advantages, draw

backs, costs, permits and site specific factors.

• Specify Control Intensity (STEP H)

This step matches control intensity with appropriate plant zones in a waterbody, producing a 

Control Intensity Map.

• Choose Integrated Treatment Scenario 

(STEP I)

This step identifies critical factors for choosing 

a combination of controls that best meet longterm management goals with the least environmental impacts.

• Develop an Action Program (STEP J)

The final step applies information from

preceeding steps to formulate a unique, longterm action plan for management of nuisance

aquatic plants in the waterbody.

IAVMP Manual

2-2

Chapter 2

v.10/99
For simplicity, the steps are presented in a recommended order. For some waterbodies, having pertinent information from prior investigations might

provide shortcuts through a few of the steps.

Certain steps can be covered more generally for

water bodies with simpler problems (e.g., early

stage pioneering infestations of non-native weed

species) compared to those with more complex

matters (e.g., large-scale, establishment of nonnative plant populations). Also, as you move

through the planning process and more complete

information becomes available on your water 

body, you may need to revisit earlier steps. For

instance, you may find it necessary to redefine the

original problem statement (Step A) or your initial

management goals (Step B). Points in the planning

process where such movements may be needed are

marked “ !” At the end of this chapter, a checklist

is provided to help you track your progress through

the planning process.

IAVMP Manual 

2-3

Chapter 2 

v.10/99
IAVMP Manual

2-4

Chapter 2

v.10/99

PLAN CHECKLIST

(check here)

( ) Step A- Develop Problem Statement (Chapter 3)

( ) Step B- Identify Management Goals (Chapter 4)

( ) Step C- Involve The Public (Chapter 5)

( ) Step D- Identify Waterbody/Watershed Features (Chapter 6)

( ) Step E- Identify Beneficial Use Areas (Chapter 7)

( ) Step F- Map and Characterize Aquatic Plants (Chapter 8)

! Checkpoint

After gathering this new information do you need to 

redefine the problem statement and/or management goals?

Yes Repeat steps A (if necessary), B, and C.

Proceed to step G

No Continue to step G

( ) Step G- Investigate Control Alternatives (Chapter 9)

( ) Step H- Specify Control Intensity (Chapter 10)

( ) Step I- Choose Integrated Treatment Scenario (Chapter 11)

! Checkpoint

Update watershed council/community 

on recommended treatment scenario.

( ) Step J- Develop Action Program (Chapter 12)

( ) Submit draft Plan to watershed council for approval

Notes:
v.10/99

What Is The Problem?

Before a group of interested people can make good

decisions about managing aquatic weeds, they

have to agree on the problem. Preparing a problem

statement is the first step for the steering committee. The problem statement should describe the

important uses of the waterbody that are being

impacted by aquatic weeds.

The committee’s first-draft of the problem statement should be presented to the rest of the community for further discussion and refinement. The

problem statement might be modified several times

before the Plan is complete.

How To Write A Clear Problem

Statement

The following steps can help you develop a 

realistic problem statement:

1.Make a list of users of the waterbody.

2.Find out how users identify the problem.

3.Group the problems into categories.

4.Condense the main categories into a

problem statement.

Let’s examine each of these tasks in more detail.

1. Make a list of users of the waterbody

It is important to identify everyone who has an

interest in the waterbody. The steering committee

itself may represent a variety of users and can start

with its own membership for ideas on who uses or

has an interest in the waterbody. Efforts should be

made to include as many different users as possible. (Read more about how to reach out to other

concerned users of the waterbody in Chapter 5-

Involve the Public.)

2. Find out how users identify the problem

Different users will have different points of view

about the waterbody’s problem. Therefore, it is

important to get a broad section of the public

involved; only then can you consider the full variety of perspectives and see to it that they are

included in the problem statement.

3. Group the problems into categories

This task involves grouping problem descriptions

according to what uses they affect. Some uses of a

waterbody that can be affected by nuisance aquatic

plant growth are:

• fishing • visual enjoyment

• wildlife habitat • swimming

• motorboat access • ecosystem function

IAVMP Manual 

3-1

CHAPTER 3

DEVELOP A PROBLEM STATEMENT 

(STEP A)

When is a Plant a Weed?

Determining whether a plant is a problem is

not always easy. In some cases, the reason

for desiring to eliminate a species is ecological, as when a species, such as the nonnative, noxious invader Eurasian watermilfoil,

threatens the health of a lake. Sometimes a

plant is considered a weed for aesthetic (it’s

considered unsightly or smelly), or economic

(it reduces property value) reasons . An individual’s attitude toward certain plants in the

waterbody can vary depending on human

usage and safety issues. For instance, surface mats of shoreline water lilies may be

pleasing to some who might never venture

into the water, but not to those who swim in

the area. Dense growth of submersed vegetation may be a problem to the angler using a

motor-boat, but not to the pilot of a float plane

that skims the surface of the water. It is

important to recognize these factors about

aquatic plants when determining if a nuisance

condition exists in a waterbody.
Problems are often associated with the amount of

vegetation as well as its location in the waterbody.

Thick stands of submersed or floating plants in

beach or shoreline areas may pose a serious safety

risk to swimmers or waders. Dense, surfacing

plants can be a hazard to those using non-motorized craft (rowers, rafters, sailboarders). Launch,

marina and dock areas clogged by weeds can hinder motorboat access. Most importantly, the presence of invasive, non-native plant species in a

waterbody is a serious situation (See box). Left

unchecked, non-native weed species such as

Eurasian watermilfoil are aggressive competitors.

They can rapidly crowd out native vegetation, 

creating serious nuisance conditions affecting

many beneficial uses.

4. Condense main categories into a problem

statement

The final task in Step A is to shorten the major categories into a brief description of the main problems posed by aquatic plants in the waterbody.

Describe the specific locations of problem plant

communities. Use numbers, if available, to

describe how the problems affect beneficial uses of

the waterbody. For example, “The number of serious swimming accidents caused this year by problem plants near the swimming beach was X,” or

“The community lost Y dollars in revenue this year

because the annual rowing event had to be called

off due to excessive aquatic plant growth.”

Statements like these make the problem statement

specific for your waterbody and your community.

Example Of A Problem Statement

After completing Step A, you will end up with a

problem statement that might sound something like

this: “In 1994, Eurasian watermilfoil was found in

Lake Serene. In the following three years, milfoil

spread throughout the boat launch area of the 100-

acre lake, forming dense shoreline stands out to 12

feet deep. In addition, dense stands of water lilies

choke the swimming area at the opposite end of

the lake.

Swimming, boating, fishing and other recreational

uses have been severely impacted. Local residents

are afraid to swim in the lake and are very concerned about the safety of their children. A special

rowing tournament held annually since 1975 on the

lake in mid-summer can no longer be conducted

due to surfacing plant growth. Cancellation of this

event resulted in an estimated loss of revenue of X

dollars annually. In addition, the average number

of fishing days in Lake Serene declined from Y

days in 1994 to Z days in 1997.”

References on Problem Statement Development

• The Lake and Reservoir Restoration Guidance 

Manual4

• Management Guide for Lakes and Reservoirs5

IAVMP Manual

3-2

Chapter 3 

v.10/99

Aquatic Weeds: How Did They Get Here?

Your lake is weed choked. How did it happen? A common means of introduction of aquatic weeds

is through stem fragments that are transported from lake-to-lake on boats, trailers, and fishing

g e a r. Non-native, invasive aquatic plants can be spread from one waterbody to another if “infected”

boating equipment is not properly inspected and all stem fragments removed. Sometimes, invasive

aquatic weeds can be purchased from aquatic nurseries for water gardens and home aquaria.

These plants are adapted to grow well, and fast, under a variety of environmental conditions. Just

like terrestrial weeds they can cause problems when they escape to natural systems. Preventing

the introduction and spread of non-native and invasive species is critical to preserving the health of

O r e g o n ’s aquatic resources.
v.10/99

Setting Aquatic-Plant Management

Goals

Once a problem statement has been drafted for

your waterbody, the next step is to come up with

specific management goals. Management goals

define what the community wants to achieve in

response to the aquatic plant problems. Defining

goals helps in selecting the best methods, which

form the heart of the Plan.

Goals vs. Methods

It is important to understand the difference

between management goals and management

methods. The goals are conditions in the waterbody that the community wants to achieve, and the

methods are the means of attaining those conditions. A goal, for example, might be to reduce

aquatic plant growth near a swimming beach so

that it is no longer a safety hazard. Mechanical

harvesting of the plants or a herbicide treatment

might be methods eventually selected to achieve

that goal. But the method cannot be chosen before

the community establishes its goals and examines

other critical aspects of the problem.

Goal-Setting Criteria

Goal-setting begins by identifying an initial set of

goals that is reasonable and realistic for the community and the waterbody. These initial goals must

address specific uses and be both practical and

attainable.

It may be useful early on to set specific criteria to

aid in goal-making decisions, such as:

• If a noxious, non-native weed is present, give 

highest priority to reducing or eliminating its 

populations, if feasible.

• Give priority to keeping a particular area clear 

of weeds, especially where human safety is at 

risk.

• Limit community outlay to less than X dollars.

• Reduce costs by using volunteer labor where 

possible.

Matching What’s Desirable With What’s

Practical

Setting goals involves balancing user desires with

the natural limitations of the waterbody and the

financial limits of the community. A goal of

removing all native plants in a lake is, under most

circumstances, a bad choice. A lake is an active,

living system, not a sterile swimming pool. Native

aquatic plants play many important roles in the

aquatic ecosystem (See Preface). Lakes with deep,

rich sediments will likely continue to support nuisance plant populations unless aggressive measures

are taken in the waterbody. Furthermore, some

control measures are very effective, but may also

be very costly.

If the community chooses not to do anything to

manage nuisance aquatic plants, it is critical to

understand the possible consequences. Will there

be impacts on human safety, recreational uses, or

aquatic life and habitat if problem conditions in the

lake are allowed to continue? Consequences of the

no action management goal become particularly

important when a waterbody is infested with an

invasive, non-native weed. In a shallow lake, these

invaders can wreak havoc on the local environment, recreational use, fish survival, and finances.

The establishment of desirable and acceptable

management goals results from conducting, from

the start, well-planned community meetings

backed by strong efforts to present all information

and gain broad based support.

IAVMP Manual 

4-1

IDENTIFY MANAGEMENT GOALS 

(STEP B)

CHAPTER 4
Example Of Aquatic-Plant

Management Goals

Here is an example of management goals for our

imaginary Lake Serene: “The management goals

are to maintain recreational uses and improve fish

habitat in the lake by removing milfoil from

known locations, and to keep swimming areas

clear of weeds for safety reasons. Additional goals

are to choose appropriate plant control methods

that are environmentally sensitive, and reduce

overall control costs by using volunteer labor when

possible.

The Importance Of Public

Involvement

TIP: As you move through the planning

process, you will continue to learn more

about your waterbody and plant problem.

With new or more complete information

available, you may need to revisit the goalsetting step to refine your management

goals. An appropriate time for reviewing initial goals would be after presenting the initial

problem statement and goals at a public

meeting of the lake community. Another time

is after determining beneficial use areas in

the waterbody.

IAVMP Manual

4-2

Chapter 4 

v.10/99
The Importance of Public

Involvement

Once an aquatic plant problem has been recognized, it is crucial to bring all interested and affected parties together early on to participate in planning. Identifying people who have an interest in

the waterbody often requires a bit of searching

early in the process; although they have a tendency

to make themselves more apparent later on, most

often after all the planning has been completed. In

addition to local residents or property owners, the

waterbody may serve a variety of stakeholder

groups with sometimes conflicting interests.

Several state, county, local, and federal agencies

may be involved. Private businesses or other interest groups may have concerns about the waterbody

as well. Fortunately, the local watershed council

includes representation of a broad range of stakeholders, and thus provides an opportunity for identifying and bringing interested parties into the

aquatic plant management planning process.

Pulling all these parties together is like weaving a

piece of fabric; each group interested in the waterbody is like a different strand of thread. As the

strands are woven into the cloth, it becomes

stronger. The end product—achieving consensus

among the parties—is like strongly interwoven

cloth. The objective is to encourage cooperation

and gather support for the management program,

but the benefits of community participation go

beyond this.

Informed citizens, agencies and other groups who

become involved in a waterbody management 

project learn about:

• The ecology of the aquatic system

• The management options for the system

• Different government agencies

• Special organizations with an 

interest in fresh-water management

• Leadership, organization, and cooperation.

IAVMP Manual 

5-1

CHAPTER 5

v.10/99

INVOLVE THE PUBLIC

(STEP C)

What is a Watershed Council?

A watershed council is a locally organized,

voluntary, non-regulatory group established to

assess the condition of a watershed and build

a work plan to implement enhancement and

protection activities. Watershed councils offer

local residents the opportunity to be involved

in making decisions that affect their watershed. Each watershed council is as unique as

the watershed they represent.

A watershed council becomes an official entity when it is recognized by a local government, usually the County Board of Commissioners. This official recognition makes the

councils better candidates for Federal and

State grants. Watershed councils should be

representative of a broad range of stakeholde r

interests including conservation, recreation,

timber, agriculture, and other interests within

their basin. The state encourages councils to

be as inclusive as possible of the various

stakeholder groups within a watershed.

For more information on forming a watershed

council call or write to the Oregon Watershed

Enhancement Board (see contacts).
Public Involvement Steps

Public involvement means participation of the

entire community. Important elements in the Public

Involvement Process are:

1. Work with the local watershed council

2. Identify interested groups

3. Conduct public meetings

4. Keep the community informed

It is the role of the steering committee to do the

initial leg work—gathering information to educate

the community, as well as working closely with the

watershed council to develop a draft management

plan for public comment and input.

1. Work with the local watershed council

The local watershed council is concerned with protecting resources within the bounds of its watershed. Thus, a management plan for a specific

waterbody should coordinate with the watershed

council. It is critical that the steering committee

maintain continuous links with the watershed

council and the larger community throughout the

planning process.

2. Identify interested groups

The steering committee identifies interested groups

and compiles a list of appropriate contacts. The

committee should already have a good handle on

potential user and interest groups, having considered this topic in Step A. Some groups that may

have an interest in management of an aquatic system are:

• Residents or property owners around the water 

body

• Special user groups (e.g., anglers, Trout 

Unlimited, Oregon Trout)

• Local government

• State and federal agencies (e.g., DEQ, ODFW)

• Native American tribes

• Water-related businesses (e.g., resorts, tackle 

& bait shops, dive shops)

• Elected officials

• Environmental groups (e.g., various fish 

groups, Nature Conservancy, Oregon Lakes 

Association)

3. Conduct public meetings

One of the best ways to reach the public is a meeting sponsored by an existing lake association or

community club. These are usually made up of

property owners around the waterbody. If no lake

association exists, it is worthwhile to form one.

Public meetings are a good way to attract individuals from within and outside the association. Local

government officials, state agency personnel, local

tribes, business people, and environmental and

other user groups should all be invited to participate in these meetings.

TIP: Many of the identified groups consist of

volunteers who may have limited time to

participate in public meetings. It is a good

idea to contact these people well in advance

of the event so they can plan their time

accordingly. Meetings will most likely need to

be scheduled for evenings or weekends.

IAVMP Manual

5-2

Chapter 5 

v.10/99

Notes on Consensus Building

Consensus building in a diverse group can be

a most challenging task. It may be difficult to

get people with different interests to agree 100

percent on an issue. But it is critical to bring all

groups together in the planning process to

constructively discuss the issues and work

toward achieving a consensus. To lead the

effort, it will be helpful to identify individuals

with strong, steadying leadership qualities.

The following are some practical suggestions

for achieving a common goal in a group:

1. Acknowledge that each person’s

opinion is important.

2. Emphasize that this is a group

endeavor.

3. Use expert advice to clarify

misconceptions.

4. Emphasize the community

benefits of management actions.
Timing is critical. Public meetings should be conducted at strategic stages in the planning process.

Critical points are:

1.At the formative stages, following completion of

Steps A and B

2.When possible plant control alternatives have 

been identified by the steering committee (after 

Step H)

3.After a control scenario has been selected, but 

before it is carried out (after Step J)

4.During implementation of the control scenario

5.During post-treatment evaluation

Widespread support is needed for implementing

any action in a public waterbody. It is crucial that

the interested parties support and accept proposed

aquatic plant management actions. It is a good idea

to collect written documentation of this support to

have on record. Later on, the supportive documentation can be useful for purposes of clarification or

emphasis.

4. Keep the community informed

Newsletters sent to association members and other

interest groups and agencies are a good way to

keep the public informed. 

The organization initiating the planning process

needs to stay in personal contact with these other

interest groups. Members of the steering committee or other association members, for example,

could accept invitations to participate in meetings

of groups interested in the lake and present information on aquatic-plant management.

References on Public Involvement/Lake

Management Organizations

• Starting and Building an Effective Lake 

Association26

• The Lake and Reservoir Restoration Guidance 

Manual (Appendix 3A)4

• Management Guide for Lakes and Reservoirs, 

Chapter 315

• Oregon Lakes AssociationH

• North American Lake Management SocietyI

IAVMP Manual 

5-3

Chapter 5

v.10/99
IAVMP Manual

NOTES:
Waterbody-Watershed Connection

A lake or river is a dynamic, living system, teeming with physical, chemical and biological activity.

The system extends beyond its shores to include

the surrounding land (the watershed) that drains

into the waterbody. A waterbody and its watershed

are inseparable. In fact, waterbody conditions 

are very much influenced by what occurs in 

the watershed.

A watershed contributes nutrients to a waterbody

that are necessary for aquatic plant growth. These

nutrients—especially phosphorus and nitrogen—

flow to the lake from all parts of the watershed by

way of streams, ground water, and stormwater

runoff. In addition, activities in the watershed, 

such as agriculture and forestry, road maintenance

and construction can all contribute silt, debris,

chemicals, and other non-point pollutants to the

waterbody.

Nonpoint pollution sources arise from more widespread, dispersed sources (Technically, some nonpoint sources can enter a waterbody through a

point source, but that is generally not the case.), in

contrast to point sources such as pipes or outfalls

that dump directly into the waterbody. Because of

these important land-water connections, integrated

aquatic plant management has to take a look at the

entire picture. A waterbody can’t be managed without understanding what makes the whole system

work. Learning about the features of both the

watershed and waterbody aids in understanding

problems in the waterbody and in designing an

effective management program.

A Plan should consider watershed problems and

identify long-term measures to reduce them.

Controlling watershed inputs from these sources

can enhance the effectiveness of primary in-lake

control measures targeting aquatic plant problems. 

In addition, since aquatic plants are integral to the

functioning of aquatic ecosystems, management

activities that influence aquatic plant abundance

and species present in a system can also impact

nutrient cycling in a lake and exacerbate existing

nutrient-related problems. So, understanding the

way an aquatic system functions as part of a watershed is necessary for development of a truly integrated management plan. It must be understood,

however, that managing nuisance growth of aquatic weeds typically requires more than implementing best management practices in the watershed. 

How To Describe The Watershed

And waterbody

This planning step is composed of two tasks:

1. Describe the watershed

2. Describe the waterbody

This step is really a fact-finding endeavor, which is

conducted by the steering committee. The committee may have already uncovered some of the background information recommended below in its preliminary search for data (See Getting Started,

Chapter 1). In fact, the local watershed council

may already have some background data in its files

on the particular waterbody.

1. Describe the watershed

To understand a waterbody’s problem, you first

need to identify features of the watershed. If the

waterbody is in a watershed with federal land in

the basin, there may be a federal watershed analysis that includes the area of interest. Contact the

local office of the Forest Service of BLM. The

Watershed Council may also have conducted a

watershed assessment using the Oregon Watershed

Assessment Manual. These documents may have

information that can help your group understand

the watershed functions that affect the waterbody.

IAVMP Manual 

v.10/99 6-1

CHAPTER 6

IDENTIFY WATERBODY/

WATERSHED FEATURES

(STEP D)
It is important to note characteristics of the watershed such as:

• Size and boundaries of the watershed

• Tributaries, wetlands and sensitive areas

• Land use activities in the watershed

• Nonpoint pollutant sources

• Existing watershed management, monitoring 

or enhancement programs

• The presence of rare, endangered or sensitive 

animals and plants

Much of this information is readily available as

documents, maps or data that can be obtained from

the local watershed council, local planning or

public works departments and state agencies.

Appendix C–Watershed and Limnological

Background Information–offers a more detailed

discussion on these topics and how and where to

collect information on your watershed.

2. Describe the waterbody

You probably know more about your lake than just

about anyone else. You can probably easily

describe your lake in general terms–you know

where the weeds are thickest, where the snags are

that can snap your prop or tangle your fishing line,

and where the big, hungry fish like to hang out.

The description of your lake that is required for a

Plan is really no different from how you would

describe your lake to a friend. However, where

your description to a friend might include observations and information on how to avoid obstacles

and where to catch fish, the observations required

for a Plan describe what it is about the waterbody

that can affect the growth of plants. Understanding

the factors that influence weed growth is an important step in controlling a nuisance weed situation.

Important waterbody features are:

• Location

• Lake basin morphology (size, shape,

and depth)

• Water sources

• Physical and chemical

characteristics (water quality)

• Biological characteristics (animals and plants)

• Shoreline uses

• Outlet control and water rights.

• Size of littoral area potentially available to 

aquatic plants

IAVMP Manual

6-2 v.10/99

Chapter 6
Because Oregon has such diverse climates, ranging

from inland desert to coastal plains to high elevation mountains, the location of your waterbody can

explain unique aspects of the problem and what

might work best in your situation. The size, shape

and depth of a waterbody determines where aquatic plants can grow, and other biological and chemical processes occurring in the waters. These factors

are especially crucial to salmon and steelhead utilization of your lake and watershed. A waterbody

is influenced by types and quantity of inflowing

and outflowing water sources. In addition, understanding water quality characteristics, such as temperature, light, dissolved oxygen levels and nutrient concentrations in the water, helps explain the

overall health and limitations of the system. From

a fisheries habitat perspective, temperature and dissolved oxygen levels are critically important to fish

survival and reproduction. Finally, there are important cultural factors on the shoreline (land use, regulating flow through the outlet) that further define

the waterbody. These physical, chemical, and biological features of freshwater ecosystems are

described in more detail in Appendix C–Watershed

and Limnological Background Information.

Getting Started In Your Search Of

The Waterbody

A number of inventories of Oregon lakes have

been conducted by various agencies in the past

several decades. Over 200 lakes in Oregon were

mapped by Portland State University and the

Oregon Department of Environmental Quality

(DEQ) during the early 1980’s. The results were

published in the Atlas of Oregon Lakes. Earlier

lake reconnaissance surveys were also performed

in the 1970’s, led by Robert McHugh of DEQ. In

addition, the U.S. Geological Survey, Water

Resources Division, conducted an extensive

statewide survey of lakes during 1973 to 1979,

publishing results in a six volume set entitled

Lakes of Oregon. The information in the earlier

surveys may be out of date, especially with respect

to land use, but they can provide much of the basic

background information required for planning.

Sampling/Monitoring To Fill 

Data Gaps

Some of the information you need to describe your

waterbody and develop a Plan may not be available. In that case, an organized information 

gathering program might be necessary to fill in

background data gaps. Much information can be

collected by lake-area residents. Special sampling

equipment is often necessary to obtain some information. In these cases, seeking the technical assistance of lake management professionals may be a

prudent decision. 

Also, certain types of water samples require analyses by approved analytical or biological laboratories. Refer to Water Quality Monitoring Technical

Guide Book32 from the 1999 Oregon Plan for

Salmon and Watershed monitoring team.

State or local lake monitoring programs may be

sources of training and assistance in setting up a

sampling program for your waterbody. The Center

for Lakes and Reservoirs at Portland State

University can provide information on measurement of basic water quality characteristics in

Oregon’s lakes and reservoirs.

References and Resources on Lake, River and

Reservoir Monitoring and Ecology

• Appendix C–Watershed and Limnological 

Background Information

• Water Quality Monitoring Technical Guide 

Book32

• Atlas of Oregon Lakes 28

• Lakes of Oregon7

• Center for Lakes and ReservoirsE

• The Lake and Reservoir Restoration Guidance 

Manuall4

• Volunteer Lake Monitoring: A Methods Manual9

• Limnology23

• Oregon Dept. of Environmental Quality staff

• Watershed council

• Local governments

• Freshwater limnologists/chemists

IAVMP Manual 

v.10/99 6-3

Chapter 6
IAVMP Manual

NOTES:
In terms of human enjoyment, freshwater systems

are popular outdoor recreational places for swimming, boating, and fishing. They also offer a variety of economic benefits such as tourism, food

supply, and transportation. Their capacity to provide aesthetic enjoyment can be immeasurable.

Freshwater bodies perform vital functions such as

flood protection, providing drinking water, and

generating electricity. More importantly, freshwater

systems provide habitat and food for aquatic life,

including fish, waterfowl and other animals.

Beneficial Uses are Protected

Lakes have multiple beneficial uses, but foremost

among them is the preservation of salmon habitat

as described in the Oregon Plan for Salmon and

Watersheds. Any management activities occurring

in freshwater systems in Oregon must be compatible with this statewide salmon conservation and

restoration program.

Beneficial uses of water bodies are protected by

Oregon State statutes. Under the State Surface

Water Quality Standards, protected beneficial uses

include fish and shellfish rearing, spawning and

harvesting, swimming, boating, navigation, irrigation, wildlife habitat, and domestic, industrial, and

agricultural water supply.

Balancing Multiple Uses

Desired uses of a waterbody must be compatible

with it’s capacity to sustain those uses, both human

and natural. Unfortunately, a single waterbody

often supports many different desirable uses,

which sometimes conflict with each other. The

management challenge involves identifying and

agreeing on uses that complement each other, and

realistically managing for these uses.

How To Determine Beneficial Use

Areas Of Your waterbody

This step focuses on identifying zones for each

beneficial use on a map of the lake. Often, the

process of defining these areas reveals the potential

for conflict. Step E consists of two tasks:

1. Identify present waterbody use areas

2. Produce a waterbody usage map

1. Identify present waterbody use areas

The first task is to identify the areas of your waterbody presently employed for beneficial uses. You

can begin this identification with the list of uses

compiled by the steering committee in Chapter 3.

For each use from that list, identify the areas

where it is most common in the waterbody.

Additional information about use areas might be

available in the zoning, wetland, or resource inventory maps you created in Chapter 5. Common use

areas include:

• Conservancy areas, including habitats that 

are integral to the lake ecosystem, such as

nesting sites, fish rearing or spawning areas, 

or locations of rare plant communities

• Boating and boat access areas (launches, 

ramps)

• Water skiing zones

• Beaches and swimming areas (public, private)

• Fishing areas

• Areas for special aquatic events (e.g., sailing, 

rowing, mini hydroplane races)

• Parks, picnic areas, nature trails, scenic over

looks

• Irrigation/water supply intakes

• Other shoreline uses 

(e.g., residential, commercial)

IAVMP Manual 

v.10/99 7-1

CHAPTER 7

IDENTIFY BENEFICIAL USE AREAS

(STEP E)
2. Develop a waterbody usage map

The next task is to draw the current waterbody use

areas on a map of the lake. This waterbody usage

map shows primary human uses, as well as habitat

areas for fish, waterfowl, and other wildlife utilizing the waterbody. As you develop this map, look

for potential conflicts in use, such as a water-skiing

zone coinciding with a fishing area.

Example of a Waterbody 

Usage Map

The following is a waterbody usage map drawn for

the imaginary Lake Serene.

IAVMP Manual

7-2

Chapter 7 

v.10/99
What Is An Aquatic Plant Survey?

Depending on a waterbody’s size, depth, and other

characteristics, aquatic plants can cover extensive

areas or occur in small, localized areas. In order to

design an effective management program specific

to your waterbody, the types of aquatic plants, their

location, and abundance must first be determined.

This can be accomplished by performing an aquatic plant survey. A survey involves systematically

traveling around the waterbody and shoreline and

noting aquatic plant presence and abundance. An

important part of the survey is collecting samples

of aquatic plants to verify the species. 

How To Map Aquatic Plants

Mapping aquatic plants in your waterbody involves

the following tasks:

1.Conduct a systematic survey of the waterbody

2.Produce an aquatic plant survey map

3.Describe beneficial and problem plant zones

1. Conduct a survey of the waterbody

Aquatic plant surveys are usually conducted at critical stages in the growth cycle of plants. Ideally,

surveys should be performed early in the growth

season (spring), at mid-season (summer), and late

in the growth season (fall). But this often can’t be

done because of time and financial limitations. A

survey at the height of the growth season (August),

when plants are most obvious, provides a practical

and valid alternative. A simple aquatic plant survey

consists of:

A. Identifying major types of aquatic

plants

B. Drawing a map of aquatic plant types

and locations in the waterbody

C. Estimating relative abundance of aquatic 

plant types

D. Collecting samples of plant species

E. Identifying substrate types

A. Identifying major types of aquatic plants

Before you start your survey, you will need to

become familiar with various types of aquatic

plants. There are generally four kinds of aquatic

plants that inhabit freshwater (See Box pg. 8.2).

The types are categorized according to how they

are attached to the sediments. The four groups are

emergent (such as cattails), freely-floating (not

rooted to the sediment, such as duckweed, coontail), rooted floating-leaved (such as water lilies),

and submersed forms (such as milfoil). The four

plant types may occupy different regions of the

lake, with emergents and floating-leaved plants

confined to shoreline margins, while submersed

and free-floating plants can extend to deeper, open

water areas. Species representing the different

plant types may also occur together in mixed communities at a specific site (e.g., rooted, floatingleaved lilies with rooted milfoil). In general, aquatic plants tend to inhabit shallow, near-shore areas

of the waterbody. In shallow water bodies, profuse

aquatic plant growth may occur throughout the

system.

B. Drawing a map of aquatic plant types and

locations in the waterbody 

You will need the following basic supplies and

equipment for your survey:

a map of your waterbody

a rope marked off in feet to measure water 

depth

a weighted rake with rope attached for 

collecting samples

a notebook, pencils, and waterproof marker

labeled plastic bags for samples

an anchor

IAVMP Manual 

v.10/99 8-1

MAP AND CHARACTERIZE 

AQUATIC PLANTS 

(STEP F)

CHAPTER 8
Keeping the four basic plant types in mind, tour the

entire waterbody by boat, noting where plants are

near or at the water surface. You may also find it

helpful to walk around the shoreline, especially if

n e a r-shore areas are clogged by weeds and make

boat passage difficult. Sketch the locations of plant

growth for the four types on a large-scale map 

of the lake, preferably one that indicates water

depth intervals and includes major landmarks for

r e f e r e n c e .

An aerial photograph of the lake may be helpful in

determining the distribution and cover of emerg e n t

and floating-leaved aquatic plants. Aerial photos

used for vegetation mapping should be taken during

mid- to late-summer when plants are at their maximum biomass. You will probably need to check on

the identity of plants you see on aerial photos by

checking the area from the ground–called “groundtruthing” in the remote sensing lexicon. Aerial photos may not be very useful for submersed aquatic

vegetation mapping because turbidity in the water

may obscure the plants.

C. Estimating relative abundance of aquatic 

plant types

The relative abundance or prominence of the aquatic plants types often indicates the overall health of

the system. Ahealthy aquatic system usually has a

variety of types and species of plants. The presence

of only a few species of plants in a waterbody may

occur where shoreline areas have been disturbed

(by an influx of sediments or other contaminants)

or have been invaded by exotic species.

In order to determine relative amounts of aquatic

plants, you will need to look at the plant beds at

representative points within the waterbody. Before

leaving shore, establish survey lines, called tran -

sects, at appropriate points along the shoreline. For

a small lake, you can mark off transects, say every

300 feet, all the way around the shoreline. Draw

IAVMP Manual

8-2

Chapter 8 

v.10/99

How to Recognize the Four Types of Aquatic Plants

Emergent aquatic plants grow rooted in saturated soils around the shoreline or in

water up to about 3 feet deep. Mature emergents’ stems, leaves, and flowers extend

well above the water surface. Many look like terrestrial plants. Soft rushes, bulrushes, cattails, and iris are typical emergent species.

Free-floating aquatic plants float on or under the water surface. Their root systems, if present, generally hang beneath the plant and are not attached to the

bottom. This diverse group ranges from large plants like coontail and water

hyacinth to very small surface-floating plants like duckweed. They are usually

found in protected areas or where water currents are very slow. Since they

absorb nutrients entirely from the water column, these aquatic plants are 

frequently found where nutrient content is high.

Rooted floating-leaved aquatic plants grow attached to the sediments in

water depths from 1.5 to 10 feet. They are recognized by oval or circular

leaves that float on or project just above the water surface.The floating leaves

are connected to the bottom by long, flexible, fairly rigid stems. Water lilies are 

common floating-leaved plants. 

Rooted submersed aquatic plants grow at water depths where light is sufficient.

Submersed plants grow with stems and leaves underwater, although some forms

also have differently-shaped floating leaves (e.g., broad-leafed pondweed). Submersed species usually have long, thin, flexible stems that are supported by the

water. Submersed plants show a variety of leaf forms, from long ribbons (long-leaf

pondweed) to feathery whorls (milfoil). Most submersed aquatic plants produce flowers above the water surface.
these lines on the lake map extending them perpendicularly from shore out to where the water is

about 20 feet deep (typically the outer limit of

growth), or its greatest depth if the lake is less than

20 feet deep.

In a boat, follow each of these lines looking at the

submersed plants through an underwater viewer.

These can be obtained at diving shops or recreational supply stores or built. At regular points

along the transect (e.g., at increments of 3 feet of

water depth), make an estimate of plant abundance

by counting the number of visible plants per unit

area of lake bottom. Estimate plant abundance as

sparse (a few plants per square yard), moderate 

(5-10 plants/square yard), or dense (more than 10

plants per square yard). Where lake water clarity is

poor, or an underwater viewer is not available, a

more general characterization of plant beds can be

obtained by deploying the sampling rake at regular

intervals and depths around the lakeshore, and 

noting plant species brought up on the rake.

D. Collecting samples of plant species

Identifying aquatic plant species is important for

several reasons. For one thing, different species

often respond differently to the same control techniques. A management technique that is very effective on one species may not work at all on another

species. It is also important to determine whether

any rare or sensitive plants are present. These

species are protected and some control techniques

may damage them.

It is crucial to find out whether any invasive, nonnative plants are present so a timely, aggressive

control program can be started. A small population

of an exotic aquatic plant species should be eliminated to prevent habitat destruction, particularly if

a plant or animal species listed under the Endangered Species Act occurs in the waterbody. To help

acquaint you with some non-native plant invaders,

Appendix B includes illustrated plant identification

factsheets of six exotic species of concern in

Oregon waters.

RED FLAG–If an invasive, exotic (nonnative) species is present in your waterbody, notify staff at Department of

Agriculture, Noxious Weed Program. A more

intensive survey should be conducted to

determine the precise locations of the exotic

plant populations. In addition, special measurements should be taken to determine 

status of infestation regardless of whether it

is in a beginning or an advanced stage

RED FLAG–If an endangered, rare or 

sensitive aquatic plant is present in your

waterbody, a more intensive survey is 

recommended to determine the precise 

locations. See discussion on the Oregon

Natural Heritage Program in Appendix C

page C4.

Samples of aquatic plants should be collected at

points along the survey transects. From the boat or

shoreline you can cast a weighted rake to the lake

bottom and pull up aquatic plants. Be sure to note

the transect line number, the location on the transect, and depth from which the sample was taken

(use your calibrated rope). Specimens collected in

this manner can be bagged and sealed for later

shipment to a specialist for identification. The box

on the following page describes how to collect and

prepare an aquatic plant sample for verification.

It is also advisable that you preserve a sample of

important plant species in your waterbody for a

permanent record. Oregon Lake Watch staff or the

Department of Agriculture can help you with ideas

on preserving plant specimens.

TIP: Many problem plant species can reproduce and spread by fragments. Be sure to

remove all plant fragments from the boat

and trailer when leaving the water. Dispose

of the fragments in a garbage can to avoid

creating new colonies of nuisance plants

within the lake or transporting the plants to

another lake. 

IAVMP Manual 

8-3

Chapter 8

v.10/99
E. Identify sediment types

Sediment types are generally classified as:

– mucky, organic

– sandy

– compact, clayey

– gravely

Sediments in the waterbody can be identified

by either collecting a bottom sample with a

small sampling dredge, by pushing a PVC pipe

into the bottom, or by examining sediment

brought up with an aquatic plant sample.

2. Produce an aquatic plant survey map

of the waterbody 

Using field notes and maps from the aquatic plant

survey, construct an aquatic plant map of the

waterbody. The aquatic plant map should show:

• Water depth contours, in feet or meters (this 

type of data is presented on bathymetric maps)

• Approximate location(s) for each of the four 

types of macrophytes

– emergents

– free-floating

– rooted, floating-leaved

– submersed

• Highlighted locations of non-native

invasive aquatic plant species, if present

• Highlighted locations of rare, sensitive, or 

endangered aquatic plant species, if present

• Locations of wetlands/conservancy areas

• General sediment types

• Tributaries/outlet(s)

• Open areas

3. Describe beneficial and problem plant

zones

Once you have mapped the aquatic plants in your

waterbody, the next step is to use that information

to write a description of beneficial and problem

plant zones. Characterizing the aquatic plant zones

allows you to determine where special control

actions are required. Task 3 consists of the following steps:

A. Describe plant types

B. Determine problem areas and beneficial 

plant zones

C. Determine need for special action

A. Describe general plant types

The purpose of this step is to write a description of

the main types of aquatic plants occurring in the

IAVMP Manual

8-4

Chapter 8 

v.10/99

How To Collect And Prepare An Aquatic Plant Sample For Verification

Step 1. Obtain an aquatic plant sample by dropping a weighted rake to the lake bottom and

pulling up the vegetation snagged by the rake. Remove the plants from the rake, sorting out the

different plant types. To keep the plants from drying out, sort them in a shallow pan filled with

water.

Step 2. Rinse a few healthy specimens of the plant types of concern with water from the lake.

Carefully lay the plant specimens between two pieces of dry paper towel, place them in a plastic

bag and seal the bag securely. Label the bag clearly with the date, name of waterbody, location

and depth of sample, and your name and telephone number.

Step 3. Mail the samples to a recognized aquatic botanist** for identification as soon as possible.

Dry plant specimens in a plastic bag can be easily mailed in a regular envelope.

Step 4. If delivering a fresh (wet) sample in person, store it in a plastic jar filled with lake water in

the refrigerator in the interim, and then transfer it to a small cooler with an ice pack for transport

to an aquatic plant expert**. Plant samples can usually be kept fresh in this way for up to five

days.

**To whom do I send an aquatic plant sample for identification?

It is critical that the plant sample be accurately identified by an aquatic botanist or a trained freshwater management professional. Contact the Department of Agriculture, Noxious Weed Program

(503-986-4621) or the PSU Center for Lakes and Reservoirs (503-725-3833) for assistance in

plant identification.
waterbody. Give the general locations of plant beds

and the maximum depth of growth. Also estimate

how much of the surface area is occupied by

plants.

B. Determine problem areas and beneficial

plant zones

Identify the parts of the waterbody affected by the

following problems:

• The presence of invasive exotic species

• Excessive native plant growth that interferes 

with important waterbody uses as swimming 

or boating.

Beneficial plant zones

Identify conservation areas, fish-rearing habitat

(especially salmon) or native vegetation considered

beneficial to fish, waterfowl, and other wildlife.

Non-native and invasive aquatic weeds are not

considered beneficial habitat for fish. A lake littoral area (aquatic plant zone) with a diverse native

plant community providing complex, multi-level

underwater structure makes ideal habitat for

salmon. Aquatic weed-infested lakes are often

dominated by one, canopy-forming species. The

high biomass and reduced light levels under an an

aquatic weed canopy may result in oxygen concentrations and pH levels that degrade habitat quality.

Rare, endangered, or sensitive plants may be present in some lakes. Zones containing these plants

should be protected. These special habitat areas

may limit use of certain aquatic plant control methods in or near the waterbody.

C. Determine special need for action in the

waterbody 

The presence of a pioneer population of nonnative, aquatic plant species signals an urgent 

situation. Because of the nuisance potential posed

by these weedy invaders, and detrimental impacts

on critical habitat, immediate action may be 

necessary.

IAVMP Manual 

8-5

Chapter 8

v.10/99

Example Of Aquatic Plant Map

The following is an example of an aquatic plant survey map produced for Lake Serene.
Example Of Written Description

Characterizing Aquatic Plants

A description of the aquatic plants in Lake Serene

might read like this: “Aquatic plant growth in this

lake is confined to a narrow band around most of

the shoreline, extending out to 12 feet in depth.

The total area of the lake occupied by aquatic

plants is estimated to be about 40 acres (or 40% 

of the entire lake area). Some isolated patches of

emergent plants, such as iris, cattails, and other

reeds and rushes occur along the shoreline. A large

water lily bed occupies the end of the lake where

the swim beach is located. The submersed plant

community is composed of sparse stands of naiad,

common elodea and small-leaf pondweed in the

shallows, and moderately-dense beds of big-leaf

pondweed occurring throughout the deeper water

areas. A large, surfacing stand of (non-native)

Eurasian watermilfoil also occurs near the boat

launch. In addition, a few scattered stands of nonnative milfoil plants are present at the opposite end

of the lake (near the swim beach), intermingled

with the other submersed plants.

The entire bay with the boat launch as well as the

near-shore region at the opposite end of the lake

are highest priority problem zones because of the

presence of the noxious, non-native weed milfoil.

These milfoil areas require special control action.

Another problem zone is the swim beach area

which is heavily populated with water lilies; these

surfacing beds make shoreline access as well as

actual swimming most difficult and dangerous.

Lake Serene supports a planted trout fishery and

nesting blue herons. The native beds of pondweed,

elodea, and naiad form an important source of food

and refuge for these and other aquatic wildlife.

Also, the wetland near the swim beach is classified

as a conservation area while recognized as a beneficial zone, and protected in the overall aquaticplant management plan.”

!

In completing the planning steps to

this point, you may have uncovered

new and critical information on the

nature and type of aquatic weed problems in

your waterbody. This new information may

affect some of your initial objectives. For

instance, you may have discovered the existence of noxious, non-native plants or sensitive plants in your waterbody. These conditions will affect your choice of management

goals and control options. If this information

wasn’t available to you as you started the

planning process, it may be necessary to

revisit STEP A and STEP B and refine the

Problem Statement and Management Goals.

Once the necessary revisions are made, they

should be presented to the larger community

for approval through the public process. Now

it is time to look at available control options.

References and Resources on Aquatic Plant

Identification

• Oregon Natural Heritage ProgramF

• Department of Agriculture, Noxious Weed 

ProgramA

• Aquatic Plant Identification and Herbicide 

Use Guide10

• Wetland Plants of the Pacific Northwest11

• Wetland Plants of Oregon and Washington30

• Common Marsh, Underwater & Floatingleaved Plants2

IAVMP Manual

8-6

Chapter 8 

v.10/99
Control Alternatives Available 

in Oregon

A variety of methods are currently being used for

controlling nuisance aquatic plants. The following

is a list of aquatic plant control alternatives available for use in Oregon:

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

• Weed Rolling

Biological Methods

• Grass Carp (irrigation and 

drainage canals only)

• Milfoil weevil

Chemical Methods

• Fluridone • Glyphosate

• Diquat • Endothall

• Copper compounds • 2,4-d

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. Table 9-1 summarizes important economic, environmental, and

logistical factors for the management techniques.

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, required permits, and provides other comments. Aquatic Plant

Management in Lakes and Reservoirs, prepared by

the North American Lake Management Society and

Aquatic Plant Management Society is a useful

resource for both the layperson and professional on

control methods as well as other aquatic plant

management topics. The manual provides a thorough, concise, and up-to-date summary of the current science and practice of aquatic plant management in North America. Other references and

resources are listed at the end of this chapter.

No action alternative

Aquatic plant management usually involves “doing

something” in the waterbody 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

waterbody 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.

It’s important to consider the potential for nuisance

non-native plants to impact fish and wildlife.

Aquatic weeds affect fish and wildlife by altering

the structure of the underwater habitat. These

effects are difficult to observe, but are none-theless important. Dense weed beds can also produce

changes in the water’s dissolved oxygen concentration, temperature, and pH that can be harmful to

aquatic life. 

Continued on page 9-6

IAVMP Manual 

v.10/99 9-1

INVESTIGATE CONTROL

ALTERNATIVES (STEP G)

CHAPTER 9
v10.99

Chapter 9 IAVMP Manual 

9-2
v10.99

IAVMP Manual Chapter 9

9-3
Chapter 9 IAVMP Manual 

9-4 v10.99
IAVMP Manual Chapter 9

v10.99 9-5
Economic impacts should also be considered.

Weeds can negatively affect tourism and commercial activities associated with use of the waterbody.

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 waterbody must be carefully considered.

References and Resources on Aquatic Plant

Control Alternatives

• Noxious Weed Program Coordinator, Oregon

Department of AgricultureA

• Aquatic Plant Management in Lakes and 

Reservoirs7

• Aquatic Plant Identification and Herbicide Use

Guide, Vol II10

• Aquatic Plant Management Program, FSEIS1

• Restoration and Management of Lakes and 

Reservoirs13

• Lake and Reservoir Restoration Guidance 

Manuall4 

IAVMP Manual 

9-6

Chapter 9

v.10/99
This step of the Plan development involves determining how much control is needed for particular

plant problems. Are there plant zones around the

lake that should be left alone (no control)? Where

should a low level of control be applied to preserve

some intermediate level of plant growth? And

under what circumstances would a high level of

control be necessary, such as where a minimal

amount of nuisance plants can be tolerated?

What Are The Different Levels of

Control?

No Control

It is best to leave special habitat areas containing

native aquatic plants untouched. In areas such as

sensitive salmonid-bearing waters described in the

Oregon Plan for Salmon and Watersheds and

shoreline wildlife conservancy areas that serve as

nesting and forage sites for waterfowl and other

animals, management actions may cause more

harm than good. Native plant beds that function as

fish spawning sites are best left alone or subjected

to minimal treatment. In some cases, the presence

of native plants may have aesthetic value to the

surrounding community. When noxious weeds are

present, however, some management action can be

taken that will benefit the aquatic system.

Low Level of Control

Low levels of control or partial removal of vegetation might be all that is needed to attain your management goals. For instance, in lakes where a

warm-water fishery is important, using mechanical

methods to develop fish lanes through vegetation

can be valuable. Low-intensity control efforts are

also important in shoreline treatments where emergent vegetation is to be protected. Low-level control maximizes enjoyment of a waterbody while

minimizing plant removal. A benefit of low-level 

control using mechanical means is the low treatment cost per acre because less plant material is

removed.

High Level of Control

The occurrence of certain aquatic plants may

require aggressive control. The presence of invasive non-native plants may justify aggressive measures to remove plants, especially where critical

salmonid habitat may be degraded. 

For safety reasons it may be necessary to clear all

vegetation from swimming or wading areas. Other

areas requiring intensive removal may include

areas around docks or boat ramps. It is important

to note that the latter two examples describe smallscale, localized treatments. Lake-wide control

efforts affecting 100 percent of aquatic plants are

seldom appropriate, except perhaps in lakes where

invasive, non-native plants are widespread and can

be selectively removed with appropriate wholelake methods.

How to Determine Levels of

Control in a Waterbody

To determine appropriate levels of plant control 

in your waterbody, refer to the waterbody usage

map and the aquatic plant map. The following

tasks describe how to use these maps to produce

a control intensity map.

TIP: If the maps are the same size and scale,

they can be overlaid. A blank map of the

waterbody showing just the shoreline outline

can be placed over these to produce the

control intensity map.

Task 1. On the usage map, identify use areas of

the waterbody that are not impacted by existing

aquatic vegetation growth. Make a list of these use

areas under the heading NO CONTROL.

IAVMP Manual 

v.10/99 10-1

SPECIFY CONTROL INTENSITY

(STEP H)

CHAPTER 10
Task 2. Next, locate areas around the waterbody

that are or have the potential to be designated conservancy zones, or are confirmed sites inhabited by

rare, endangered, threatened or state listed sensitive plant or wildlife species, particularly salmon.

Add these areas to the NO CONTROL list.

Task 3. On the usage map, identify use areas of

the waterbody that require some control of existing

aquatic vegetation growth. Make a list of these use

areas under the heading LOW CONTROL.

Task 4. Referring to the aquatic plant map,

recheck that low control areas do not contain

endangered, rare, or sensitive plant populations. 

If they do, remove from low control list.

Task 5. On the usage map, identify use areas that

require maximal removal of aquatic plant growth.

Make a list of these areas under the heading HIGH

CONTROL.

Task 6. Referring to the aquatic plant map, locate

areas with invasive, non-native plant populations

(like Eurasian watermilfoil or Brazilian elodea).

Include these areas on the list of HIGH 

CONTROL.

References and Resources on Sensitive Plants

and Animals

• Oregon Plan for Salmon and WatershedsD

• National Heritage ProgramF

IAVMP Manual

10-2

Chapter 10

v.10/99

Example of a Control Intensity Map

The end product is a map clearly showing zones of all three control intensities. Construction of a 

control intensity map will aid in choosing appropriate treatment options for each area of the lake 

(Chapter 11).
The Integrated Approach—

A Juggling Act

This step involves choosing a combination of control efforts that best meet the management goals

and financial resources of waterbody users, and

produces the least impact on the environment. The

procedure consists of evaluating each control

option listed in Chapter 9 using an integrated vegetation management approach. This approach examines the alternatives with regard to such factors as:

• 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

• Endangered or threatened species impacts

• Other environmental impacts and the 

associated mitigation, if needed

• Program costs

• Permit requirements (Federal, State, local)

Reviewing control alternatives in light of these and

other site-specific factors provides a means of narrowing down the options into an appropriate management package. No management program, however, is without impacts or consequences. No management program is inexpensive, 100% effective

and 100% environmentally friendly. Choosing a

management program requires a careful weighing

of all the factors. The trick in deciding a course of

action is to achieve a balance between expected

management goals and cost, that results in a net

environmental benefit.

A Procedure For Choosing An

Appropriate Treatment Scenario

Using the Control Intensity Map, match each control zone (no control, low control, high control)

with an appropriate control method. The following

considerations are important:

• 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, may not be appropriate. 

The same logic applies 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 (1 year, 2 years, 

more)?

• Site-specific constraints that might affect use 

of control method.

Does the site have a lot of submerged logs,

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?

IAVMP Manual 

v.10/99 11-1

CHOOSE INTEGRATED 

TREATMENT SCENARIO (STEP I)

Chapter 11
• Capital costs and operation/maintenance 

c o s t s .

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.

• Human safety and health concerns.

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 waterbody.

Does the aquatic system have important fish 

spawning sites? If so, control activities that 

disturb the bottom would be prohibited during 

certain critical life cycle periods. Furthermore, 

the presence of endangered, rare, or sensitive 

plants or animals, especially salmon species, that 

may utilize aquatic plant beds could prevent or 

limit the use of certain control methods.The life 

cycles of the desirable plant and animal species 

have to be considered and the timing of control 

activities adjusted to minimize impact.

• Balancing enhancement of beneficial human 

uses with environmental pro t e c t i o n .

What are the projected short-term and long-term 

impacts on the local environment? Is there a risk 

that control for the sake of maximizing human 

use could seriously jeopardize an important 

segment of the native aquatic plant or animal 

c o m m u n i t y ?

• Possible m i t i g a t i o n techniques and costs, 

including replacement of untargeted plants 

that are re m o v e d .

Some aquatic plant control techniques pose 

higher risks of removing non-target organisms, 

particularly emergent vegetation along the shore

line. 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 eff o r t s .

• Local, county, state or Federal permit 

re q u i re m e n t s .

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 11 -1 ) .

While most permits for aquatic plant control 

work in freshwater are free, some have an 

assessed fee.

• Obtain permission of owners.

Many small lakebeds are privately owned. 

L a rger ones may have public ownership due to 

their “navagability.,” The Division of State Lands

is the management agency responsible for 

publicly owned waterways.

Example Of Recommended

Treatment Scenario

The following is an example of a recommended

treatment scenario produced for Lake Serene:

LAKE SERENE RECOMMENDED 

T R E AT M E N T S C E N A R I O

• 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 

( S p r i n g ) .

–Second-year milfoil treatment: Diver hand 

removal/bottom barrier application on residual 

populations (Spring).

– Water lily treatment: Systemic herbicide/bottom 

barrier (Spring).

• Watershed controls.

IAVMP Manual 

11-2

Chapter 11

v.10/99
IAVMP Manual 

11-3

Chapter 11

v.10/99

!

You have come a long way in gathering critical information and evaluating

plant control options with regard to

the specifics of your waterbody 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.

Permit / Document

Remove and Fill

Natural Heritage Program

Letter confirming search

of data for critical plant

or animal species

Fish Planting Permits

Local Permits

NPDESPermit 402 / 401

Section 10 Permit

Section 404 Permit

APHIS Form 526

Agency

Division of

State Lands

The Nature

Conservancy

Dept. of Fish &

Wildlife

Local 

jurisdictions

Oregon Dept.

of Env. Quality

Army Corps of

Engineers

Army Corps of

Engineers

Oregon Dept.

of Agriculture

Description

Permit required if more than 50 cu. yds of sediment are disturbed.

Natural Heritage Program is a State repository of

data on endangered, threatened, & sensitive plant

species, native wetland plant communities, aquatic

& non-vegetation wetland systems.

A permit is required for stocking of triploid (sterile) grass carp in Oregon waters for control of

aquatic vegetation. Currently only approved for

irrigation districts.

Permits may be required on the local level for various activities, such as shoreline management or

Growth Management Act/Sensitive Area ordinance.

Permit/certification may be required for return

water from hydraulic dredging disposal site.

Dredging in navigable waters in the US.

Disposal of dredged or fill material in waters of

US.

Application and permit to move live plant pests or

noxious weeds.

Control

Activities

dredging, 

rotovating

search should

be conducted

for any control

activity.

grass carp

stocking

variable

dredge material

disposal

dredging

dredging, boat

ramps, shoreline armoring

importing milfoil weevils

45 Days

3-7 Days

60 Days

variable

Call

ODEQ

Call COE

Call COE

Call ODA

Table 11-1. Who Permits What?

Permits / Documents Required Aquatic Weed Control Acitvities in Oregon

Mimimum

Process

Time
IAVMP Manual

NOTES:
Putting All The Pieces Together

The final task is to take all the information and formulate a long-term action program (plan) for

aquatic plant management. This Plan provides the

community with guidance and direction for aquatic

plant management in their particular waterbody.

The decision to proceed with aquatic plant control

in a waterbody is just the beginning. Followthrough is critical. Aquatic plant control is an

ongoing concern that requires long-term commitment. This is particularly true of water bodies with

exotic plant infestations or with nuisance plant

growth that has developed over many years. In

these situations, achieving management goals

could take many years. The Plan should be flexible

and evolving. It should provide for regular checking of how well the actions are working and allow

for modification as conditions change.

Components Of The Action Plan

While the integrated treatment scenario forms the

heart of the Plan, there are other activities that are

also essential components of the management program. These include program budgeting, evaluating program effectiveness, organizing public outreach and exotic weed prevention programs, developing funding strategies, and identifying shortterm and long-term actions. These components are

all linked together by the critical element of time.

Appropriate start-up time and duration of each of

these activities can vary

widely. For these reasons, it

is important to divide the

action plan into short-term

and long-term program elements.

1.Review and recheck the recommended 

integrated treatment scenario. The following 

factors need to be determined:

• Costs

• Permit requirements

• Human safety/health

• Environmental impacts, particularly if critical

salmon habitat exists within the project site

• Mitigation, if needed

• Acceptability to waterbody property owners,

users and other interested parties

2.Compute costs and a budget to implement the

overall program.

In particular, identify:

• Planning costs

• Contracted treatment costs

• Capital costs (for equipment or materials)

• Operation and maintenance costs

• Equipment replacement costs

• Program monitoring/evaluation costs

• Mitigation costs

• Permit costs

3.Determine monitoring and evaluation 

strategies to evaluate the program’s success.

In particular, you will need to:

a.Determine methods to track short- and longterm nuisance plant growth trends.

b.Evaluate the effectiveness of your annual 

program with respect to meeting management 

goals.

4.Plan a public outreach program.

Educational information about the aquatic plant

management program can be disseminated 

through:

• Public meetings

• Newsletters and media coverage

• Posted signs around the waterbody

• Special events highlighting management 

IAVMP Manual 

v.10/99 12-1

CHAPTER 12

DEVELOP AN ACTION PROGRAM

(STEP J)
activities on the waterbody such as workshops

or lake fairs.

5.Plan an exotic weed prevention program.

The old adage “an ounce of prevention saves a 

pound of cure” really holds true when it 

comes to exotic weed invaders. The Plan 

should contain an exotic (non-native) weed 

prevention component to limit introduction 

of non-native weeds to the waterbody and to 

provide a means of quick response if exotic 

weeds are sighted. Exotic weed invaders 

such as Eurasian watermilfoil, Brazilian 

elodea and hydrilla spread primarily by frag

mentation (breaking off of stem pieces) and 

transport on boating equipment. Efforts to 

halt the spread through educational means, 

by a citizen watch for these invaders in the 

water body, and by visual inspection of boats 

entering and leaving the waterbody are 

recommended.

6.Develop funding strategies.

a.Identify community groups with an interest in 

the waterbody.

b.Identify the level and duration of needed 

funding.

c.Assess all funding options, including:

• Voluntary donations for aquatic plant control

• Formation of a lake or property owner 

association with the ability to collect

revenue

• Establishment of a weed control or water 

improvement district or other taxing 

district

• Grants or loans from public agencies or 

other outside sources:

- Oregon Watershed Enhancement Board 

- Oregon Department of Agriculture Weed

Program 

- Oregon Department of Environmental

Quality 319 grant program

d.Identify an action plan based on optimal short 

and long-term funding sources to accomplish 

the plan. Incorporate into points 7 and 8.

7.Construct a short-term action plan.

Some elements of the Plan may be initiated 

immediately. Control methods like handpulling 

are usually small scale and have no permit 

requirements, so they can be implemented as 

soon as plants begin to show growth in early 

spring. Mechanical harvesting is usually 

performed later in the season when plant growth 

is at its peak so it is important to contact a harvester the winter before to schedule a treatment.

Volunteer efforts can be used for some activities. 

Many home or property owner watershed controls can be implemented right away. Public out

reach programs on scheduled management activities can be started immediately with little or no 

cost. 

8.Construct a long-term action plan.

Other elements of the Plan may require more 

time for completion, to procure funding, or to 

obtain permits. Certain techniques require repeat

treatments over several years for optimal effectiveness (e.g., diver dredging, rotovation). The 

timeframe for processing permits may be extended if multiple permits are required or several 

agencies are involved in the review process. It 

may take time to advertise for specialized contract services such as diver dredging.

!

The planning process results in a written Plan that summarizes all the information that you have gathered. The

written document provides the basis for annual

review of short-term and long-term elements of

the Plan. It is recommended that a three ring

binder with tabs for each planning step be used

to organize your planning document. In this way,

any new information, monitoring results and necessary changes in the program can be easily

documented for future use. Your plan should

have the following written components:

Problem statement

Management goals

A list of waterbody and watershed characteristics from previous studies or current 

sampling work

IAVMP Manual

12-2

Chapter 12

v.10/99
IAVMP Manual 

12-3

Chapter 12 

v.10/99

A map showing beneficial and recreational 

use areas of the waterbody

A map showing types and locations of 

aquatic plants

A written description of aquatic plants

A discussion of aquatic plant controls, examining pros and cons of use in the waterbody 

(results can be presented in a matrix format)

A control intensity map showing proposed 

control areas in the waterbody

Description of public involvement program, 

including specific examples

A list of action strategies, both short and 

long-term, and time frames

A description of the monitoring and evaluation process to be used

A description of the long-term action plan, 

periodically modified to changing conditions 

as indicated by the monitoring/evaluation 

program

A budget outlining how any potential funding 

will be used

A written plan containing these elements will serve

you well in overall management of aquatic plants,

as well as in meeting requirements of certain public funding sources. This dynamic plan is your

guide to adaptive management, fine-tuned over the

years as conditions in or affecting your waterbody

change with time.

The Road Well Traveled

Congratulations on completing your Plan!

Throughout the planning process, you have learned

about the workings of the waterbody and its watershed, as well as aquatic plant management in

Oregon and its applicability to your waterbody.

You have learned how to organize and work

together, and most of all, how to compromise.

Now you can begin the process of initiating the

aquatic plant management program uniquely 

created for your waterbody.
IAVMP Manual

NOTES:
IAVMP Manual 

13-1

CHAPTER 13

v.10/99

The period between development of an integrated

aquatic plant management plan and implementation of the plan is a time for excitement, paperwork and patience! It involves scheduling, public

outreach, securing permits and funding, and

arranging for volunteer and contracted services.

The duration of this period largely depends on the

scale, intensity and complexity of the plant control

program. Once these necessary items have been

taken care of, you are indeed off and running!

Permits And Other Requirements

After the Plan has been approved and adopted,

steps can be taken to secure required permits for

control measures. The role of the permit process in

the protection and management of our State’s

freshwater resources is a necessary and important

one (See Box). The permits, fees, and notification

procedures depend on the control methods to be

used and the size, type or other special features of

the waterbody. (See Chapter 11 for summary information on permits necessary for certain control

activities conducted in Oregon.) Often, several

jurisdictions may be involved in the permitting

process for a project. As a result, you may need to

make a few phone calls to secure information and

application forms. Funding

Finding the right mechanisms for collecting funds

is important. If major costs of the program are

being funded by private contributions, outline a

schedule for collecting committed donations. Local

funds may be provided by financing through special community club or lake association assessments. It is best to start such an assessment process

well in advance of the need for initial outlay of

funds. Forming a water improvement district is a

way to procure funds through special tax assessments. Timely completion of grant applications is

critical if funding has to be secured through competitive, cost-sharing grant programs such as those

administered by OWEB (Oregon Watershed

Enhancement Board) or DEQ’s 319 program.

I HAVE A PLAN - WHAT’S NEXT?

Why Are Permits Needed?

Anyone planning aquatic plant management

activities in their waterbody should be aware

of the various State and local regulations protecting freshwater resources and aquatic life.

There is no single regulation governing

aquatic resources in our State, nor a single

agency wholly responsible for overseeing

freshwater activities. However, there are a

number of laws regarding water quality, fisheries, wildlife, and habitat, and many different

agencies responsible for administering these

laws. In most cases, authorities overlap on

both the local and State levels, and sometimes the Federal level, especially if critical

salmon habitat areas or navigable waters are

affected. You should check with local and

county public works or planning departments

on what permits are required for a particular

control activity in your lake or stream.

Personnel with Oregon Departments of

Environmental Quality, Agriculture, and Fish

and Wildlife can assist you with information

on permits required by State agencies.
IAVMP Manual

13-2

Chapter 13 

v.10/99

Implementation Needs

Management

Once the plan is approved by the planning committee and larger community, start lining up volunteers for parts of the program where citizen labor

can be used. It may be beneficial for your association or club to expand the functions of the steering

committee or establish a special aquatic plant management committee to oversee the long-term management program. Whether the project is large and

complex or small and simple, each facet of the

program will need to be managed.

Monitoring Program Effectiveness

A carefully designed aquatic plant management

program can be successful and satisfying. But it

also requires long-term commitment and flexibility. Depending on the severity of problems in the

waterbody, it can take many years to achieve specific management goals. Furthermore, conditions

in the waterbody or community needs may change

over time. As a result, an aquatic plant management program must include a monitoring element

to regularly evaluate treatment effectiveness and

recommend program adjustments as needed. The

effectiveness of the overall program should be

assessed on an annual basis at a minimum.

Progress in meeting management goals can be

quantitatively tracked by directly sampling/measuring problem plant populations at strategic times

during the year. Your local watershed council can

provide assistance in planning a monitoring project

for your waterbody.

On a more informal note, it may also be helpful to

conduct periodic surveys of the community to gain

their impressions of effectiveness of the program.

During the implementation phase, it’s important to

be patient, be realistic in your expectations, and

keep the lines of communication open!

Keeping Everyone Informed

It is critical to keep the community informed about

the progress of the control project. In particular,

give advance notice of any inconveniences that

might be experienced by users of the waterbody as

a consequence of in-lake activities. The community will want to know about the findings of posttreatment monitoring and evaluation of the control

effectiveness. In going through the planning

process described in this manual, you have already

started the educational ball rolling. Through public

meetings, newsletters, barbecues, and local media

coverage, you’ve gotten word out that a problem

exists in your waterbody but there’s a way to 

tackle it. Continue to use informational avenues

that have worked for you to update the community

on important aspects or results of the control

program. 

In following the planning steps in this Manual,

you have created a unique document—your

PLAN! The Plan describes the best path to inte -

grated aquatic plant management in your water -

body. Good luck in your aquatic plant manage -

ment efforts!
APPENDIX A

Glossary of Terms
Blank IAVMP Manual
Algae — Small aquatic plants containing chlorophyll and without roots that occur as single cells or

multi-celled colonies. Algae form the base of the

food chain in aquatic environments.

Algal bloom — Heavy growth of algae in and on a

body of water as a result of high nutrient concentrations.

Alkalinity — The acid combining capacity of a

(carbonate) solution, also describes its buffering

capacity.

Aquatic plant survey — A systematic mapping of

types and location of aquatic plants in a waterbody,

usually conducted by means of a boat. Survey

information is presented on an aquatic plant map.

BMPs (Best Management Practices) — Practices

or methods used to prevent or reduce amounts of

nutrients, sediments, chemicals or other pollutants

from entering water bodies from human activities.

BMPs have been developed for agricultural, silvacultural, construction, and urban 

activities.

Bathymetric map — A map showing depth contours in a waterbody. Bottom contours are usually

presented as lines of equal depth, in meters or feet. 

Benthal — Bottom area of the lake (Gr. benthos

depth).

Biocontrol — Management using biological

organisms, such as fish, insects or micro-organisms

like fungus.

Biomass — The total organic matter present (Gr.

bios life).

Bottom barriers — Synthetic or natural fiber

sheets of material used to cover and kill plants

growing on the bottom of a waterbody; also called

sediment covers.

Chlorophyll — The green pigments of plants (Gr.

chloros green, phyllon leaf).

Consumers — Organisms that nourish themselves

on particulate organic matter (Lat. consumere to

take wholly).

Contact herbicide -— An herbicide that causes

localized injury or death to plant tissues with

which it contacts. Contact herbicides do not kill

the entire plant. Aquathol®and diquat are contact

type herbicides.

Control intensity map -— A map of a waterbody

showing areas requiring no, low or high levels of

aquatic plant control. See Chapter 10.

Decomposers — Organisms, mostly bacteria or

fungi, that break down complex organic material

into its inorganic constituents.

Detritus — Settleable material suspended in the

water: organic detritus, from the decomposition of

the broken down remains of organisms; inorganic

detritus, settleable mineral materials.

2,4-d (2-4-dichlorophenoxy acetic acid) —The

active chemical ingredient of the aquatic systemic

herbicides Aqua-Kleen®and Weedar 64®.

Diquat — The active chemical ingredient of the

aquatic contact herbicide Ortho Diquat®.

Dissolved oxygen — A measure of the amount of

oxygen gas dissolved in water and available for

use by microorganisms and fish.

Drainage basin — The area drained by, or contributing to, a stream, lake, or other waterbody (see

watershed).

Drawdown — Decreasing the level of standing

water in a waterbody to expose bottom sediments

and rooted plants. Water level drawdown can be

accomplished by physically releasing a volume of

water through a controlled outlet structure or by

preventing recharge of a system from a primary

external source.

Dredging — Physical methods of digging into the

bottom of a waterbody to remove sediment, plants

IAVMP Manual 

A-1

Appendix A

v.10/99

GLOSSARY OF TERMS
or other material. Dredging can be performed

using mechanical or hydraulic equipment.

Ecology — Scientific study of relationships

between organisms and their surroundings (environment).

Ecosystems — Any complex of living organisms

together with all the other biotic and abiotic (nonliving) factors which affect them.

Emergent plants — Aquatic plants that are rooted

or anchored in the sediment around shorelines, but

have stems and leaves extending well above the

water surface. Cattails and bulrushes are examples

of emergent plants.

Endothall — The active chemical ingredient of

the aquatic contact herbicide Aquathol®.

Epilimnion — The uppermost, warm, well-mixed

layer of a lake (Gr. epi on, limne lake).

Eradication — Complete removal of a specific

organism from a specified location, usually refers

to a noxious, invasive species. Under most circumstances, eradication of a population from a site is

very difficult to achieve.

Euphotic zone — That part of a waterbody where

light penetration is sufficient to maintain photosynthesis.

Eutrophic — Waters with an ample supply of

nutrients and hence a rich organic production (Gr.

eu well, trophein to nourish).

Exotic — Refers to species of plants or animals

that are not native to a particular region into which

they have moved or invaded. Eurasian watermilfoil, Brazilian elodea, and hydrilla are exotic plant

invaders in Oregon.

Floating-leafed plant — Plants with oval or circular leaves floating on the water surface, but are

rooted or attached to sediments by long, flexible

stems. Waterlilies are examples of rooted floatingleafed plants.

Fluridone — The active chemical ingredient of

the systemic aquatic herbicide SONAR®.

Flushing rate — Term describing rate of water

volume replacement of a waterbody, usually

expressed as basin volume per unit time needed to

replace the waterbody volume with inflowing

water. The inverse of the flushing rate is the

(hydraulic) detention time. A lake with a flushing

rate of 1 lake volume per year has a detention time

of 1 year.

Free-floating plants — Plants that float on or

under the water surface, unattached by roots to the

bottom. Some have small root systems that simply

hang beneath the plant. Water hyacinth and tiny

duckweed are examples of free-floating plants.

Glyphosate — The active chemical ingredient of

the systemic herbicide RODEO ®.

Grass carp — Also known as white amur, grass

carp (Ctenopharyngodon idella) is a large, vegetation-eating member of the minnow family

(Cyprinidae). Originally from Russia and China,

these plant grazers are sometimes used as biological agents to control growth of certain aquatic

plants. Oregon permits grass carp in irrigation

canals and in lakes and reservoirs less than 10

acres in size.

Herbicide — A chemical used to suppress the

growth of or kill plants.

Habitat — The physical place where an organism

lives.

Hydraulic detention time — The period of detention of water in a basin. The inverse of detention

time is flushing rate. A lake with a detention time

of one year has a flushing rate of 1 lake volume

per year.

Hypolimnion — The cold, deepest layer of a lake

that is removed from surface influences (Gr. hypo

under, limne lake).

Integrated aquatic plant management —

Management using the best combination of plant

IAVMP Manual

A-2

Appendix A

v.10/99
control methods that optimizes target weed species

control, maximizes beneficial uses, minimizes

environmental impacts and optimizes overall costs.

Limiting nutrient — Essential nutrient needed for

growth of plant organism which is the most scarce

in the environment. Oftentimes, in freshwater systems, either phosphorus or nitrogen may be the

limiting nutrient for plant growth.

Limnology — The study of inland waters (Gr.

limne lake).

Littoral — The region of a body of water extending from shoreline outward to the greatest depth

occupied by rooted aquatic plants.

Macro-algae — Large, easily seen (macroscopic)

algae. The macro-algae Nitella sp. sometimes

forms dense plant beds and can be a conspicuous

member of the aquatic plant community.

Macrophyte — Large, rooted or floating aquatic

plants that may bear flowers and seeds. Some

plants, like duckweed and coontail, are free-floating and are not attached to the bottom.

Occasionally, filamentous algae like Nitella sp. can

form large, extensive populations and be an 

important member of the aquatic macrophyte 

community.

Mitigation — Actions taken to replace or restore

animals or plants that may have been damaged or

removed by certain prior activities.

Morphology — Study of shape, configuration or

form (Gr. morphe form, logos discourse).

Niche — The position or role of an organism within its community and ecosystem.

Nitrogen — A chemical constituent (nutrient)

essential for life. Nitrogen is a primary nutrient

necessary for plant growth.

Non point (pollutant) source — A diffuse source

of water pollution that does not discharge through

a pipe or other readily identifiable structure. Non

point pollution typically originates from activities

on land and the water. Examples of non point

sources are agricultural, forest, and construction

sites, marinas, urban streets and properties.

Non-target species — A species not intentionally

targeted for control by a pesticide or herbicide.

Noxious weed — Non-native plant species that,

because of aggressive growth habits, can threaten

native plant communities, wetlands or agricultural

lands. The Oregon State Department of

Agriculture, Noxious Weed Control Program has

the authority to designate certain plants as “noxious” in the state. Eurasian watermilfoil

(Myriophyllum spicatum) is a designated noxious

weed in Oregon.

Nutrient — Any chemical element, ion, or compound required by an organism for the continuation of growth, reproduction, and other life

processes.

Oligotrophic — Waters that are nutrient poor and

have little organic production (Gr. oligos small,

trophein to nourish).

Oregon Plan for Salmon and Watersheds —

Oregon initiative that focuses on increasing salmon

and steelhead populations, restoring habitat, and

improving water quality through cooperative

efforts of local communities, watershed councils,

and agencies and other groups with management

interest in salmonid fisheries.

Oxidation — A chemical process that can occur in

the uptake of oxygen.

pH — The negative logarithm of the hydrogen ion

activity.

Phosphorus — A chemical constituent (nutrient)

essential for life. Phosphorus is a primary nutrient

necessary for plant growth.

Photosynthesis — Production of organic matter

(carbohydrate) from inorganic carbon and water in

the presence of light (Gr. phos, photos light, synthesis placing together).

Phytoplankton — Free floating microscopic

plants (algae) (Gr. phyton plant).

IAVMP Manual 

A-3

Appendix A

v.10/99
Point (pollutant) source — A source of pollutants

or contaminants that discharges through a pipe or

culvert. Point sources, such as an industrial or

sewage outfall, are usually readily identified.

Pollutant — A contaminant, a substance that is not

naturally present in water or occurs in unnatural

amounts that can degrade the physical, chemical,

or biological properties of the water. Pollutants can

be chemicals, disease-producing organisms, silt,

toxic metals, oxygen-demanding materials, to

name a few.

Primary production — The rate of formation of

organic matter or sugars in plant cells from light,

water and carbon dioxide (Lat. primus first, producere to bring forward). Algae are primary producers.

Problem statement — A written description of

important uses of a waterbody that are being

affected by the presence of problem aquatic plants.

See Chapter 3.

Producers — Organisms that are able to build up

their body substance from inorganic materials (Lat.

producere to bring forward).

Public Awareness/Outreach — Programs

designed to share technical information and data

on a particular topic, usually associated with activities (such as management) on or around a waterbody.

Residence time — The average length of time that

water or a chemical constituent remains in a lake.

Rotovation — A mechanical control method of

tilling lake or river sediments to physically dislodge rooted plants. Also known as bottom tillage

or derooting.

Secchi disc — Typically a 20-cm (8-inch) diameter disc painted white and black in alternating

quadrants. It is used to measure light transparency

in lakes.

Sediment — Solid material deposited in the bottom of a basin.

Sensitive areas — Critical areas in the landscape,

such as wetlands, aquifer recharge areas, and fish

and wildlife habitat conservation areas.

Standing crop — The biomass present in a body

of water at a particular time.

Steering committee — A small group of people

organized to represent the larger community of

individuals, businesses, agencies and organizations

who have an interest in management of a particular

waterbody. The steering committee is responsible

for following the planning steps outlined in this

manual.

Stratification — See thermal stratification.

Submersed plant — An aquatic plant that grows

with all or most of its stems and leaves below the

water surface. Submersed plants usually grow rooted in the bottom and have thin, flexible stems supported by the water. Common submersed plants are

milfoils and pondweeds.

Susceptibility — The sensitivity or level of injury

demonstrated by a plant to effects of an herbicide.

Systemic herbicide — An herbicide in which the

active chemicals are absorbed and translocated

within the entire plant system, including roots.

Depending on the active ingredient, systemic herbicides affect certain biochemical reactions in the

plant that can cause plant death. SONAR®and

RODEO®and Aqua-Kleen®(2,4-d) are systemic

herbicides.

Thermal stratification — Horizontal layering of

water in a lake caused by temperature-related differences in density. A thermally stratified lake is

generally divided into the epilimnion (uppermost,

warm, mixed layer), metalimnion (middle layer of

rapid change in temperature and density) and

hypolimnion (lowest, cool, least mixed layer).

Thermocline — (Gr. therme heat, klinein to

slope.) Zone (horizontal layer) in waterbody in

which there is a rapid rate of temperature decrease

with depth. Also called metalimnion, it lies below

the epilimnion.

IAVMP Manual

A-4

Appendix A

v.10/99
Topographic map — A map showing elevation of

the landscape in contours of equal height (elevation) above sea level. This can be used to identify

boundaries of a watershed.

Transect lines — Straight lines extending across

an area to be surveyed.

Tributaries — Rivers, streams or other channels

that flow into a waterbody.

Triclopyr — The active ingredient of a systemic

herbicide being evaluated in Washington for aquatic plant control.

Triploid — A genetic term referring to non-reproducing (sterile) forms of grass carp induced by

manipulating reproductive genes. Reproducing

grass carp have two pairs of chromosomes and are

termed diploid. Triploid fish have three sets of

chromosomes.

Trophic state — Term used to describe the productivity of the lake ecosystem and classify it as

oligotrophic (low productivity, “good” water quality), mesotrophic (moderate productivity), or

eutrophic (high productivity; “poor” water quality).

Vascular plant— A vascular plant possesses specialized cells that conduct fluids and nutrients

throughout the plant. The xylem conducts water

and the phloem transports food.

Waterbody usage map — A map of a waterbody

showing important human use areas or zones (such

as swimming, boating, fishing) and habitat areas

for fish, wildlife and waterfowl. See Chapter 7.

Watershed — The entire surface landscape that

contributes water to a lake or river. See drainage

basin.

Watershed council — This council of individuals

is a locally organized, voluntary, non-regulatory

group established to assess conditions of their local

watershed and build a work plan to implement

enhancement and protection activities within their

watershed.

Watershed management — The management of

the natural resources of a drainage basin for the

production and protection of water supplies and

water-based resources.

Watershed snapshot — A simple drawing of a

waterbody and its watershed showing important

identifying features such as watershed boundary

lines, inlet and outlet streams, wetlands, landuse

zones and other site-specific characteristics. This is

a simple way of condensing background data and

information on a project area and displaying slected features in a picture.

Wetland — A generalized term for a broad group

of wet habitats. Wetlands are areas of vegetation

that are transitional between land and water bodies

and range from being permanently wet to intermittently water covered. 

The regulatory definition of a wetland used by

EPA, COE, and ODSL is as follows: 

“Those areas that are inundated or saturated

by surface or ground water at a frequency and

duration sufficient to support, and that under

normal circumstances do support, a preva -

lence of vegetation typically adapted for life in

saturated soil conditions. Wetlands generally

include swamps, marshes, bogs, and similar

areas.”

Zooplankton — Microscopic animal plankton in

water. Daphnia sp. or water fleas are freshwater

zooplankton.

IAVMP Manual 

A-5

Appendix A

v.10/99
Blank IAVMP Manual
APPENDIX B 

Invasive, Non-native Aquatic Plant Fact Sheets
Blank IAVMP Manual 
IAVMP Manual Appendix B

v10.99

INVASIVE, NON-NATIVE AQUATIC PLANT FACT

SHEETS

Introduction

Correct identification of aquatic plants is important, especially with regard to invasive, non-native

species. The presence of an exotic species in a system signals a serious potential threat to the local ecology and aggressive action is usually warranted to control invasive weed populations. Also, control strategies that are effective on one of these species may not be effective on another. The following factsheets

are presented to aid in identification of six non-native aquatic species of concern in Oregon freshwater

systems. The six invader plant species are:

• Eurasian watermilfoil (Myriophyllum spicatum) • hydrilla (Hydrilla verticillata)

• parrotfeather (Myriophyllum aquaticum) • fanwort (Cabomba caroliniana)

• Brazilian elodea (Egeria densa) • water hyacinth (Eichhornia crassipes)

Usually there are key features that easily differentiate aquatic plant species, but in some cases plants

require careful scrutiny for correct identification. Hydrilla, and Brazilian elodea, which are designated

“noxious weeds” in Oregon, and native Elodea canadensis are perhaps the most difficult species to correctly identify. The importance of accurate identification is aptly illustrated by this trio of plants. Hydrilla

is one of the most damaging of the non-native aquatic plants. While hydrilla has not been documented in

Oregon waters to date, in 1995 a pioneering infestation of this invasive weed was confirmed in Pipe and

Lucerne Lakes (King County) in western Washington State. Care must be taken not to mistake hydrilla

for one of the other plants in the trio because it requires special, rapid action to control its spread. A

comparison of these three plants is included in this section (see figure, A Comparison). If in doubt–call

an expert!

Myriophyllum (milfoil) species may also require careful observation for correct identification. There are

two weedy milfoils in Oregon: Eurasian watermilfoil, a State noxious weed designate, and parrotfeather,

a species of concern. Parrotfeather has distinctive emergent leaves, while Eurasian watermilfoil and the

two native milfoils are mostly submersed (except for the flower stalks). In addition to the native milfoils,

several other aquatic plants are commonly mistaken for Eurasian watermilfoil. The milfoils of Oregon

are compared in this section and some widespread, native aquatic plants that you may find in your lake

are illustrated.

Plants are amazingly adaptable organisms. Since they are usually rooted and can’t move around to search

out hospitable environments like animals do, plants adjust their growth to match the environment that

they find themselves in. The form of an aquatic plant, like all plants, is determined by an intricate interaction between its environment and biology. Photos and drawings cannot convey the rich variation possible as individual plants respond to their unique environment. The illustrations shown here represent the

general features of the plant. The plants you find in your lake should be compared to the illustrations

with special consideration of the key features mentioned in the text. If identification is in doubt contact

an expert (see Appendix F for a list of people who can answer your questions).
Appendix B IAVMP Manual 

v10.99

The Myriophyllums

Eurasian watermilfoil (Myriophyllum spicatum)

a common submersed aquatic weed

Parrotfeather (Myriophyllum aquaticum)

an emergent aquatic weed

Northern watermilfoil (Myriophyllum sibiricum)

a native aquatic plant

Whorled watermilfoil (Myriophyllum verticillatum)

a native aquatic plant
IAVMP Manual Appendix B

v10.99

Eurasian watermilfoil

(Myriophyllum spicatum L. )

Description

Milfoil has finely dissected leaves that form in whorls of 4 on the stem. Milfoil leaves fall off as they

age, so occasionally you may find less than four leaves in a whorl, especially near the bottom of the

plant. Leaves near the surface are often a reddish or brown color. Eurasian watermilfoil generally has 

12-16 pairs of leaflets on each leaf. It’s often difficult to separate Eurasian watermilfoil from its native

cousins: northern watermilfoil and whorled watermilfoil. Calling an expert at Department of Agriculture,

Noxious Weed Control Program may be the best way to positively identify your milfoil.

Growth Habit

Eurasian watermilfoil is the culprit in many nuisance aquatic plant cases in Oregon. It has been the subject of much research, and its growth habits are well known. Milfoil overwinters as short bright green

stems from a few inches to a few feet long-rooted in the sediments. Milfoil stores energy and nutrients in

its roots over the winter. In early spring, plants grow rapidly to the surface where they can form a mat or

canopy of branches. Rapid spring growth and canopy formation allows milfoil to outgrow and shade out

other, more desirable native plants.

Propagation

Milfoil is spread primarily by stem fragments. Fragments are formed when pieces of the plant are cut off

of the main plant body, such as by a boat propeller or during harvesting operations. These stems fragments can root and produce new plants. Milfoil also fragments naturally. In the late summer, the stems of

milfoil become quite brittle and roots begin to form on the stem. Wave action or a duck paddling though

a milfoil bed can cause stems to break.

Control

Prevention of Eurasian watermilfoil invasion requires control of fragment spread. Some management

techniques, harvesting for example, can create fragments and contribute to the spread of milfoil. Milfoil

is susceptible to several herbicides, including 2,4-d, endothall and fluridone. With the proper herbicide

and application rate, milfoil can be selectively removed from an aquatic system, leaving more desirable

aquatic plant species. Other intensive methods, such as bottom barrier placement and diver-dredging are

effective against small-scale infestations of milfoil. Milfoil is relatively unpalatable and is low on the

grass carp preference scale, especially if other more palatable species are present. Other biological controls of milfoil are under intensive investigation, although none are likely to be available soon.
Appendix B IAVMP Manual 

v10.99

Key features:

• 12 to 16 leaflets on each leaf •No emergent leaves

• Leaves near surface may be •Milfoil leaflets look like “feathers” 

reddish or brown

• Emergent flower stalks sometimes during the summer

Eurasian watermilfoil

(Myriophyllum spicatum L.)
IAVMP Manual Appendix B

v10.99

Parrotfeather

(Myriophyllum aquaticum (Vell.) Verdc.)

Description

Parrotfeather has both emergent and submersed leaves. The submersed leaves are finely-dissected, and

feathery, often with a reddish color. The submersed growth form of parrotfeather is easily mistaken for

Eurasian watermilfoil (Myriophyllum spicatum L.). The emergent stems can be from a few inches to over

a foot high and are the most distinctive feature of parrotfeather. Emergent leaves form in whorls on the

stem. Leaves are bright green and finely divided. In spring, very small, white, tuft-like flowers form

where the emergent leaves attach to the stem.

Growth Habit

Parrotfeather grows best when rooted in shallow water. In nutrient-enriched lakes parrotfeather can grow

as a floating plant in deep water. The emergent stems can survive on wet banks of rivers and lake shores,

so it is well adapted to moderate water level fluctuations. Parrotfeather’s distribution in Oregon is

thought to be limited to coastal lakes and streams and the Columbia River system in southwest Oregon.

Parrotfeather invasion of lakes and streams severely changes the physical and chemical characteristics of

the aquatic ecosystem. The emergent stems shade the water column eliminating algae growth, which is

the basis of the aquatic food web. Parrotfeather is also excellent habitat for mosquito larvae.

Propagation

Parrotfeather spreads only by plant fragments. All the parrotfeather plants in Oregon are female. In fact,

there are no male plants anywhere outside of its native range in South America. Consequently, there is no

sexual reproduction and no seeds are formed. Parrotfeather rhizomes are quite tough and can be transported long distances on boat trailers. Parrotfeather’s attractive green foliage make it a popular aquascaping plant, which has contributed to its spread.

Control

Parrotfeather has a high tannin content, which makes it unpalatable for most grazers, including grass

carp. Parrotfeather is sensitive to many herbicides, but a thick cuticle, which forms a waxy cover on the

emergent leaves, hampers aerial application of herbicides. Research has shown that parrotfeather growing

in water deeper than about 20 inches may be particularly sensitive to reduction in phosphorus concentrations in the water column.
Appendix B IAVMP Manual 

v10.99

Key features:

• Bright green, christmas-tree like emergent stems

• Dense mat of intertwined rhizomes in the water with abundant, long roots

• Reddish feathery-leaved, very limp submersed leaves may be present

Parrotfeather

(Miriophyllum aquaticum (Vell.) Verdc.)
IAVMP Manual Appendix B

v10.99

Brazilian elodea

(Egeria densa Planch. )

Description

Brazilian elodea is often confused with Hydrilla and Common elodea. Since Common elodea is a native

species and Hydrilla an extremely aggressive invader, it is important that the plants be correctly identified. Common elodea has three leaves per whorl, Brazilian elodea four (sometimes eight) leaves per

whorl, and Hydrilla five leaves per whorl. Common elodea leaves are usually less than 1/2 inch long and

about 1/4 inch wide. Brazilian elodea leaves are greater than 1/2 inch long and less than 1/4 inch wide.

Hydrilla has small “prickle hairs” on the leaf edges and spines on the midvein of the leaf that gives the

plants a rough feeling. Hydrilla also forms small (1/4 to 1/2 inch long) tubers in the sediment, which are

not formed by the other two species. Brazilian elodea has three-petaled, white flowers, less than an inch

in diameter, that float on the water surface.

Growth Habit

Brazilian elodea is rooted in the sediment and grows rapidly in the spring, forming a canopy of intertwined stems at the surface that shades out native aquatic plants. It is a popular aquarium plant, commonly sold in tropical fish stores. The characteristics that make Brazilian elodea a popular aquarium plant:

rapid growth under low light levels, easy propagation, and tolerance of a wide range of water and sediment types, also makes it a nuisance aquatic plant when it escapes and grows in lakes and streams. 

Propagation

Plant fragments are the primary mode of spread of Brazilian elodea. Fragments are formed when pieces

of the plant are cut off of the main plant body, such as by a boat propeller or during harvesting operations. These stems fragments can root and produce new plants. 

Control

As with other aquatic plants that are spread by stem fragments, prevention of Brazilian elodea fragment

spread is critical to preventing the invasion of new lakes. Some management techniques, harvesting for

example, can create fragments and contribute to the spread of Brazilian elodea. Once established,

Brazilian elodea is susceptible to several herbicides and appears to be a preferred species grazed by grass

carp. Other methods, such as bottom barrier placement and diver-dredging are effective against smallscale infestations of Brazilian elodea.
Appendix B IAVMP Manual 

v10.99

Key features:

• Submersed, sometimes with floating white • No tubers attached to roots in

flowers sediment

• Leaves in whorls of four or eight

• Leaves greater than one-half inch long and less than one-quarter inch wide

Brazillian Elodea

(Egeria densa Planch.)
IAVMP Manual Appendix B

v10.99

Hydrilla

(Hydrilla verticillata (L.F.) Royle)

Description

Hydrilla closely resembles its cousins Brazilian elodea (Egeria densa) and common elodea (Elodea

canadensis), both widespread in Oregon. The primary distinguishing feature of Hydrilla is the presence

of tubers that form on the roots. Tubers are small potato-like structures 1/4 to 1/2 inch long. Hydrilla also

has small prickles on its leaves that give the plant a rough feel. Hydrilla typically has 3 to 8 leaves in a

whorl around the stem that are 1/10 to 1/8 inch wide and 1/4 to 3/4 inches long. Hydrilla also forms turions (small, hard buds) on the stem and has small (1/2 inch diameter) white, floating flowers.

Growth habit

Hydrilla is a submersed plant that is rooted in the sediment. Hydrilla is probably the most troublesome

submersed aquatic plant in North America. It grows rapidly under very low light levels, in a variety of

aquatic habitats from static to flowing water and at depths from an inch to 50 feet. The stem branches in

the upper parts of the water column, forming a canopy that inhibits growth of native species and interferes with recreational use of lakes.

Propagation

Hydrilla has three primary means of spread: stem fragments, tubers, and turions. Stem fragments are

formed by harvesting operations and by boat props. Each stem piece can root and form a new plant.

Tubers form on the roots in the sediment, and turions form on the stem in the water column. Tubers are

produced in the sediment by the thousands, and sprout in the spring. Turions are smaller and are easily

carried by water currents, providing a mechanism for long distance transport. Some strains of Hydrilla

can set very small seeds.

Control

Hydrilla hasn’t been found in Oregon yet. It is such a troublesome plant in other parts of the country,

however, that it would be dangerous if a small, pioneer colony were over-looked or missidentfied.

Nearby, California has been battling outbreaks of this weed for many years. In 1996 a pioneering infestation of hydrilla was confirmed in Pipe Lake, King County in western Washington State, and is now

undergoing aggressive treatment. Tubers and turions complicate control strategies. There is currently no

technique, short of dredging, to remove tubers from the sediment once they are formed. Herbicide treatments can kill vegetative parts of the plant but do not affect the tubers. Grass carp will readily eat leaves

and stems of Hydrilla, but do not eat the tubers. No biocontrol agent has been found that can effectively

attack tubers in areas with even mild winters.
Appendix B IAVMP Manual 

v10.99

Hydrilla

(Hydrilla verticillata (L.F.) Royle)

Key features:

• Tubers (one-quarter to one-half inch long potato-like propagules) attached to roots 

in the sediment 

• Tiny spines and “prickle hairs” on the leaves give hydrilla a rough feel
IAVMP Manual Appendix B

v10.99

Fanwort

(Cabomba caroliniana Gray)

Description

Fanwort has distinctive fan-shaped submersed leaves arranged in pairs on the stem. In the water, fanwort

has a “tubular” look because leaves are quite dense on the stem and there is little branching. Submersed

leaves resemble those of water buttercup (Ranunculus aquatilus). Buttercup leaves, however, are

arranged alternately (one per node) on the stem. Distinctive, but small, floating leaves may also be present. Floating leaves are long (less than one-half inch) and narrow (less than one-quarter inch). The stem

attaches to the floating leaf blade at the center where there is a slight constriction. Small (less than onehalf inch diameter), white flowers float on the water surface.

Growth Habit

Fanwort is a rooted aquatic plant with a limited distribution in the Northwest. In Oregon fanwort has

infested several coastal lowland lakes and is present in side-channels of the Columbia River. Fanwort has

been in Cullaby Lake, on the north coast of Oregon, for at least 10 years where it creates severe nuisance

conditions. However, no extensive surveys have been conducted to determine its real extent. In contrast

to other rooted aquatic plants, fanwort is reported to obtain nutrients important for growth from the water

column rather than the sediment. Fanwort is a serious aquatic weed as far north as upstate New York and

Michigan. It clearly has the ability to grow and create serious weed problems in Oregon.

Propagation

Like many problem aquatic plants, fanwort can regenerate from small stem fragments. Fanwort stems

become brittle in late summer, which causes the plant to break apart, facilitating distribution and invasion

of new water bodies. Fanwort is self-pollinating in the South and seeds readily germinate. Yet, seeds collected in New Jersey failed to germinate. There is no information on seed viability in the Northwest. 

Control

There has been little research on fanwort biology or management. Fanwort shows varying susceptibility

to the herbicides available for management in Oregon. Fanwort has greater sensitivity to the contact herbicides diquat and endothall used in conjunction with complexed copper. Drawdown has been used to

reduce fanwort growth in the South, however, extreme drying is necessary to prevent regrowth from

seeds. Grass carp eat fanwort but there has been no research on other biocontrol agents. Because it may

obtain most of its important nutrients from the water, fanwort may be sensitive to reduction in nutrients

in the water. At the least, prompt action and vigilant monitoring of our lakes may prevent further spread

of fanwort and increased management costs in the future.
Appendix B IAVMP Manual 

v10.99

Fanwort

(Cabomba caroliniana Gray)

Key features:

• Fan-shaped leaves in pairs on the submersed stem

• Submersed stems have a “tubular” appearance

• Small (less than one inch long), oval floating leaves with stem attached in the center
IAVMP Manual Appendix B

v10.99

Water hyacinth

(Eichhornia crassipes (Mart.) Solms)

Description

Water hyacinth is a floating plant with round to oval leaves up to 10 inches in diameter, although smaller

leaves are common. Leaves are bright green and shiny and held upright so they act like sails, which facilitates distribution of the plant. The leaf stalk is spongy and thick and helps to keep the plant bouyant. A

mass of fine roots hang in the water column. Flowers are large (2-3 inches) and attractive. They are blueish purple or lilac colored with a yellow spot. Water hyacinth can be purchased in nurseries throughout

Oregon, however, it has not become established in natural systems.

Growth Habit

Water hyacinth can form impenetrable mats of floating vegetation. Water hyacinth has not been found in

the wild in Oregon but it is sold as an ornamental plant in garden stores in the state. Although it is

thought that water hyacinth cannot survive Oregon’s winters, its presence as an ornamental makes it possible for escape and growth in the wild under the right conditions. 

Propagation

Water hyacinth reproduces by seeds and vegetatively. Daughter plants form on rhizomes forming dense

beds of water hyacinth. In one study, two plants produced 1200 daughter plants in four months.

Individual plants break off of the mat and are dispersed by water currents. As many as 5000 seeds can be

produced by a single plant. Seeds are eaten and transported by water fowl. The seeds sink to the bottom

and may remain viable for 15 years. Seedlings are common on mud banks exposed by low water levels. 

Control

The best way to manage water hyacinth is to keep it from becoming established in Oregon. One important means of controlling the introduction of water hyacinth is to keep them from escaping from ornamental ponds and backyard pools. Grass carp will eat water hyacinth and the plant can be managed with

herbicides. All management options are very expensive and require an ongoing commitment. Be aware of

the threat of water hyacinth and report any sitings to your local weed board and/or the Oregon

Department of Agriculture, Noxious Weed Control Program!
Appendix B IAVMP Manual 

v10.99

Key features:

• Floating bunches of oval leaves that form a dense surface mat

• Long roots dangling in the water

• Attractive, hyacinth-colored (purplish) flowers

Water hyacinth

(Eichhornia crassipes (Mart.) Solms)
APPENDIX C

Watershed and Limnological Background

Information
Blank IAVMP Manual 
Watershed Size/Boundaries

The size and topography of the watershed can significantly influence the waterbody. Watershed

boundaries are marked by ridges and hilltops. The

most obvious sources of drainage to a waterbody

are inflowing rivers and streams (called tributaries). Other sources of inflow include surface

flow or overland wash (often evident as water running over the ground, such as after a rainstorm).

Water inflow below the surface of the ground to a

lake or river is called groundwater. In cases where

no streams flow into the waterbody, the watershed

is the area from which groundwater is captured to

supply the waterbody along with rainfall runoff.

Tributaries, Wetlands and

Sensitive Areas

Tributaries

Identifying tributaries (rivers, streams, creeks)

flowing into your waterbody can help you locate

major sources of incoming waters. Land uses near

these streams may also be important in controlling

long-term water quality. Streams are effective at

sculpting the land by cutting into and scouring

channels which creates sediment along the way.

They also transport sediment, nutrients, and other

materials downstream where they are eventually

deposited. Streams are shown on USGS quad maps

and other general maps. The best source for stream

mapping is your watershed council.

Wetlands and Sensitive Areas

It is important to determine if there are any wetlands or sensitive areas adjacent to the problem

waterbody. Certain aquatic plant control actions

could impact these special, often fragile areas of

vegetation. National Wetland Inventory Maps

(based on USGS quad series) are good sources and

can be obtained from Division of State Lands.

Local bookstores or map supply stores often stock

or will special order these maps for you. Check

with your local or county Planning Department for

a map of sensitive areas as defined by local

Sensitive Areas Ordinances.

How to Determine Boundaries of a Watershed

A map showing the watershed boundaries (usually the area from which surface water flows toward

the waterbody) is a very useful tool. Often a watershed map already exists for your lake or river.

Watershed maps are sometimes available from your local watershed council or Public Works or

Planning Department of your county or city.

If a watershed map does not exist for your particular waterbody, you can construct one by using a

topographic map. A topographic map shows a series of concentric circles called contour lines. Each

contour line represents points on the surface that are the same elevation. The scale on topographic maps usually is presented in feet (or meters) above mean sea level (MSL). USGS quad maps

also show contours, usually in 20 foot increments. Topographic or USGS quad maps can be

obtained from local Public Works or Planning Departments, National Wetlands Inventory (US Fish

& Wildlife), map stores or outdoor recreation stores. U.S. Geological Survey sometimes has regional groundwater maps, which would be useful for seepage lakes (groundwater-fed).

To find the watershed boundaries, read from the waterbody shoreline (the low point) outward on all

sides to the highest elevation. Stop at the point before elevation readings begin to decrease. Once

you have an initial boundary, check again to see you didn’t stop too soon at a dip on the map. For

guidance see “Watershed Fundamentals” in the Oregon Watershed Assessment Manual. Local or

county staff can also assist you in checking watershed boundaries.

I. Watershed Features

IAVMP Manual 

C-1

Appendix C

v10.99
Land Use Activities In the

Watershed

Human activities around a waterbody can have a

significant influence on the aquatic system.

Reducing pollutant inputs from livestock, croplands, forestry, residential properties and other

sources can help protect the quality of the waterbody in the long term. These pollution sources, left

unchecked, could make the water quality worse

over time. Yet, while controlling these inputs helps

reduce contamination, control of these sources

alone is unlikely to provide a short-term solution to

aquatic-plant problems. In most cases, in-lake

management efforts form the primary means of

dealing with the immediate problem of nuisance

plants.

You can view recent aerial photos, if available, to

get “the big picture” of the area around the waterbody. These may be obtained from your local or

county Public Works or Planning Departments.

The Division of State Lands and Regional Corps of

Engineers Office also has aerial photos in black

and white and sometimes in color. Aerial photos

give an important bird’s-eye view of the watershed, but it may not be enough. For more detail on

land uses, zoning maps and land use maps can help

define the now as well as what the future may

bring. Contact your local Planning Department for

zoning maps and information on development

trends in the region.

Point And Nonpoint Pollutant

Source Locations

The watershed not only contributes water to maintain the waterbody, but also sediment, nutrients,

organic matter and contaminants that can wash into

the lake or river. Pollutants can originate from two

types of sources: point and nonpoint. Point sources

arise from a distinct source that can be easily

traced; they typically discharge through a pipe,

conduit or outfall structure. Sources of nutrients

and contaminants that do not originate from a pipe

are commonly referred to as nonpoint sources.

These sources are more diffuse in nature and may

not be as obvious as piped discharges. Nonpoint

sources include runoff from agricultural areas,

forests, urban runoff (lawns, driveways, roadways),

construction sites, seepage from septic tanks, discharges from marina and recreational boating and

other widespread sources.

Since seeping or failing septic systems are often

found to be sources of nonpoint pollution, areas

with on-site waste treatment/disposal systems

should be identified. A quick means of identifying

potential nonpoint sources of pollution from septic

systems around a waterbody can be accomplished

by reviewing zoning maps from the Planning

Department or as-built plans of developed communities. You can also contact local Public Health

Department for more information.

IAVMP Manual 

C-2

Appendix C

v10.99

303(d) List of Water Quality Limited Waterbodies

Currently about 100 lakes and reservoirs in Oregon are listed by the Department of Environmental

Quality (DEQ) as water quality limited, or “303(d) listed” waterbodies, or “waterbodies of potential

concern”. The 303(d) list, which is a list of streams, rivers, lakes and reservoirs that fail to meet

water quality standards, is required of all states as part of the 1972 federal Clean Water Act. The

list only identifies the water quality problems of the waterbody (e.g., high chlorophyll a concentrations, turbidity, algae, weeds), not the causes. Causes of water quality problems are investigated

and corrective actions are proposed later on as management plans are developed. Oregon

Departments of Agriculture and Environmental Quality are charged with developing management

plans for all the waterbodies on the 303(d) list. Copies of the 303(d) list and associated documents

are available at public libraries throughout Oregon and all DEQ offices and on the web at

http://waterquality.deq.state.or.us/wq/. For more information, you can call DEQ’s water quality division at (503) 229-5279 or toll free in Oregon at 1-(800) 452-4011.
While nonpoint source loadings can originate from

anywhere in the watershed, certain land use practices such as agriculture, construction, and city

streets contribute greater inputs than other land

uses such as forests and well-vegetated areas.

Small quantities of pollutants from many sources

in a watershed can have a cumulative effect, and

can severely impact the quality of the receiving

waters. Water quality can become so degraded that

the waterbody fails to meet critical protective

water quality standards (See Box on 303(d) listed

waterbodies).

Existing Watershed Management,

Monitoring, Or Enhancement

Programs

Integrated aquatic plant management takes the

holistic view, working in cooperation with other

management efforts in the watershed. Of primary

importance is the recent efforts embodied in the

Oregon Plan for Salmon and Watersheds (See

Box), which focuses on water quality improvement

and native fish habitat restoration. The steering

committee will need to work closely with its local

watershed council and conservation team to develop a plan compatible with salmon enhancement

efforts in the watershed. 

If any management activites in critical habitat for

federally listed threatened or endangered salmon

species are being proposed, the steering committee

should coordinate with the appropriate federal

management agency (National Marine Fisheries

Service or U. S. Fish and Wildlife Service) and

ODFW to ensure that detrimental impacts to listed

species do not occur.

There are things that everyone can do in the watershed to limit point and nonpoint inputs to lakes,

rivers and streams. Best Management Practices

(BMPs) in agriculture, construction, home and

yard practices are methods designed to prevent or

reduce loadings of nutrients, sediments, pesticides,

and other contaminants to receiving waters. In

addition to zoning (information supplied

The Oregon Plan for Salmon and

Watersheds.

Initiated in 1997, Oregon’s Salmon and

Watershed Plan is designed to restore

salmon to a level at which they can once

again be a part of people’s lives.

Development of this program was instigated

by the threat of federal endangered species

listing of coastal coho salmon. While the

Oregon Plan focuses on the needs of salmon

and steelhead, it will conserve and restore

crucial elements of natural systems that support fish, wildlife and people. The Oregon

Plan has four key elements:

1. Coordinated Agency Programs

A number of state and federal agencies

administer laws, policies, and management

programs that affect all life cycle stages of

salmon and steelhead. Under this plan, governmental agencies that impact salmon are

accountable for coordinated programs consistent with conservation and restoration efforts.

2. Community Based Action

Government alone cannot conserve and

restore salmon and steelhead. With agencies

providing technical and regulatory support,

restoration activities are performed at the

local level.

3. Monitoring

Annual monitoring will be conducted to determine levels of response of salmon habitats

and populations to conservation and restoration efforts.

4. Appropriate Corrective Actions 

The Oregon Plan calls for making appropriate changes to current programs as needed

and improving compliance with existing laws

without introduction of new ordinances.

You can view the Oregon Plan on the web at:

http://www.oregon-plan.org/

IAVMP Manual 

C-3

Appendix C

v10.99
IAVMP Manual 

C-4

Appendix C

v10.99

by your local Planning Department), there may be

watershed management programs such as agricultural BMP activities through your Conservation 

District or septic tank maintenance programs

through your local Health Department or County

Cooperative Extension Service.

The Presence Of Rare,

Endangered, Or Sensitive Animals

And Plants

Oregon’s Natural Heritage Program maintains a

database on endangered or high quality native

plant and animal species. The Natural Heritage

Program, administered by the Division of State

Lands and the Nature Conservancy, is responsible

for information on the state’s endangered, threatened, and sensitive plants as well as high quality

native plant communities and wetlands. Similarly,

the Oregon Department of Fish and Wildlife manages and interprets data on wildlife species of concern in the state. Although the Natural Heritage

Program does not contain a complete inventory of

all natural features in Oregon, the database is continually updated.

The presence of rare, endangered or other state

sensitive animal or plants species in the immediate

area being considered for aquatic plant treatment

may pose certain limitations on those activities.

This is particularly true for use of certain aquatic

plant control techniques, such as aquatic

herbicides.

Location, Size, Depth, and Shape 

Location

A thorough description of where your lake is located is an important element in a Plan. A complete

description should include the County, Township,

Range, Section, and coordinates of your lake. This

information can be obtained from topographic

maps published by the U.S. Geological Survey, or

from soils maps consulted in your characterization

of the watershed.

Size

The size, depth, and shape of a lake determines the

area colonizable by aquatic plants and also influences the mixing that occurs in the lake. The timing and degree of mixing of lake water is 

a characteristic feature for each lake and is a key

determinant of the productivity of the ecosystem.

Size can vary from less than an acre to thousands

of acres. Aquatic plants can typically cover a larger percentage of the lake area in small lakes and

consequently play a larger role in the overall functioning of the ecosystem in small lakes than in

large lakes.

Depth

The depth of a lake tells us much about the biology and productivity of the lake. In deep lakes, surface waters warm during the summer while bottom

waters remain cool. This thermal stratification in

deep lakes affects mixing of water in the lake.

Deep waters do not mix with the surface waters.

This can have profound impacts on the amount of

nutrients entering the lake, the growth of algae,

water clarity, and the area colonizable by nuisance

aquatic plants. Shallow water bodies typically support more aquatic plants than deeper, steeper-sided

basins.

Basin Shape

The measurement of the shape of the lake basin is

called bathymetry. Bathymetric lake maps are

based on a series of depth measurements. Depth 

is usually measured at intervals along transects.

These measurements are plotted on a map of the

lake and contours drawn to provide a topographic

map of the basin. The depth and size (area) of a

lake determine the lake volume, which, in turn,

determines the hydrology of the system.

II. Waterbody Features
Shoreline Shape

The shape of the shoreline can also provide information about the lake’s biology and

physical/chemical characteristics. Lakes with many

embayments and an irregular shoreline have more

shallow areas, and are consequently more susceptible to nuisance plant growth. Similarly, a long narrow lake has a greater shoreline length, i.e., more

shallow areas, than a more circular lake with the

same area.

Water Sources (Tributaries,

Groundwater) And Hydrology

A waterbody is defined by characteristics of water

flow. As water is impounded in a basin, a stream or

river becomes a reservoir or lake. The period of

detention of water in a basin is called the hydraulic

detention time. The detention time can vary from

days to years, depending upon the volume and

flow through a particular waterbody. The inverse

of detention time is the flushing rate, which is how

fast the water in a lake is replaced. A lake with a

detention time of 1 year has a water replacement,

or flushing rate, of 1 lake volume/year. A lake with

a 1/2 year detention time has a flushing rate of 2

lake volumes/year, a 2 year detention time gives a

flushing rate of 1/2 lake volumes/year, etc. A short

detention time (high water flow rates and low lake

volume) results in a flushing rate that is so high

that algal cells produced in the water column are

washed out of the system faster than they can be

replaced. Consequently, high flushing rates lead to

low algal biomass, clear water, better and deeper

light penetration into the lake, and better aquatic

plant growth conditions. 

Since water flow defines a waterbody and also

influences its biological characteristics, it is important to consider the sources and volumes of water

entering and leaving your lake. Are streams flowing in and out of the lake? Do they flow all year or

seasonally? Is more water entering the lake than is

flowing out? If so, the lake may be recharging the

groundwater. If more is flowing out than is flowing

in groundwater may be moving into the lake.

Streams are also important in terms of fisheries

support as well as possibly contributing to downstream movement of aquatic plant problems.

Physical, Chemical And Biological

Characteristics Of The Waterbody

And Tributaries

Rooted aquatic plants compete with algae for light

and nutrients in the water column. Removal of the

aquatic plants may increase light availability and

result in enhanced algae growth. If water column

nutrient levels are high enough nuisance algae

blooms may occur. Therefore, in order to prevent

exchanging a nuisance aquatic plant problem for a

nuisance algae problem you must consider whether

the light, temperature, and nutrient environment of

the lake and its tributaries may support nuisance

algae growth. Some of the required information

may be available from the sources listed at the

beginning of this section. If the data are incomplete or inadequate, a sampling program may be

required to fill the gaps.

Physical/Chemical (Water Quality)

Characteristics

Transparency

Water transparency is one of the oldest and easiest

methods for describing a lake. Over the years the

method of measuring transparency has been standardized to allow comparisons of measurements

taken by different people in different lakes. The

standard method utilizes a Secchi disk to measure

transparency. A Secchi disk is a large diameter,

black and white plate that can be lowered into the

water on a rope. The depth at which the disk disappears from view (the Secchi depth) is related to the

amount of materials (algae, sediment, and dissolved organic material) suspended in the water

column. The Secchi depth has been correlated with

a number of indices that indicate the overall productivity of the lake, including the maximum depth

at which aquatic plants can grow.

Temperature

Temperature profiles are important descriptive

information because of the effect of temperature on

IAVMP Manual 

C-5

Appendix C

v10.99
biology and water density. Most biochemical reactions occur more rapidly at higher temperatures.

Water temperature is an important determinant of

photosynthesis rate in plants and respiration rates

of plants and animals. Temperature determines the

rate of growth of aquatic plants, and triggers the

onset of growth in the spring and the fall dieback.

Temperature also influences the density of water.

Surface warming can lead to thermal stratification,

as mentioned above, which can have significant

impacts on nutrient availability, distribution and

concentrations in lakes. In addition, extensive shallow areas (which typically have high aquatic plant

densities) may undergo larger night/day temperature fluctuations than deeper, off-shore waters,

which can lead to onshore-offshore water currents

that can shorten herbicide contact times and effectiveness.

Dissolved Oxygen

Measurement of dissolved oxygen profiles in the

lake can provide much information about the overall functioning and productivity of the lake. All of

the organisms that are commonly observed in lakes

require oxygen to survive. In stratified lakes, oxygen in the cool, dark bottom waters can be used up

by the bacteria that decay and decompose the dead

algae cells that rain down from the warmer and

more well-lit surface waters. Loss of dissolved

oxygen in the bottom waters makes those waters

inhospitable for fish and many other aquatic organisms. Loss of oxygen also causes chemical changes

in the sediment that result in the release of nutrients that can fuel growth of algae and rootless

aquatic plants, like coontail (Ceratophyllum

demersum), in the lake.

Alkalinity

Alkalinity is a measure of the ability of water to

resist changes in pH (a measure of acidity). Large

fluctuations in pH can occur on a daily basis in

lakes with low alkalinity and dense aquatic plant

growth because of the chemical reactions of photosynthesis. Plant photosynthesis uses the energy of

sunlight to convert the carbon in carbon dioxide

and bicarbonate ions into plant tissue. The removal

of carbon dioxide from the water causes pH to

increase. During the night, respiration of plant tissues releases carbon dioxide into the water, causing pH to decrease. Extreme high and low pH can

influence a number of chemical reactions that

determine the availability of nutrients in the lake,

and can lead to chemical toxicity problems for fish

and insects.

Phosphorus

In many lakes the concentration of phosphorus in

the water determines the growth rate of algae.

Therefore, measurement of the concentration of

phosphorus in the water is an indication of the

potential productivity of algae in the lake. Two

forms of phosphorus are generally measured in

lakes. Dissolved, inorganic phosphorus is readily

available for plant and algae uptake. Total phosphorus includes dissolved phosphorus and the

phosphorus that is associated with algae, zooplankton, and particles in the water.

Phosphorus concentrations can vary considerably

with depth in stratified lakes. Low dissolved oxygen concentrations in bottom waters of stratified

lakes can result in a chemical reaction that causes

phosphorus to be released from the sediment to the

water. As a consequence, bottom waters can have

much higher phosphorus concentrations than surface waters.

Nitrogen

Nitrogen often limits aquatic plant growth and can

occasionally limit algae growth. As with phosphorus, there are inorganic and organic forms of nitrogen. Inorganic nitrogen can exist in three forms in

lakes: nitrite, nitrate, and ammonia. Nitrite is usually present in only very small amounts. As with

many other chemical constituents, the distribution

of inorganic nitrogen varies with depth in stratified

lakes. Nitrate is generally most abundant in the

surface waters, and ammonia dominates the bottom

waters. Presence of nitrates in the bottom waters

may indicate that groundwater is entering the lake.

High concentrations of ammonia and/or nitrates in

the surface waters may suggest that there is septic

pollution present.

IAVMP Manual 

C-6

Appendix C

v10.99
Biological Characteristics

Your lake is a complex community made up of a

variety of interacting plants and animals. Aquatic

weeds and algae make up the plant community.

Fish, zooplankton, insects, and wildlife interact

with each other and the plant community to make

a functioning aquatic ecosystem. The aquatic plant

community is discussed in greater detail in Chapter

8-Map Aquatic Plants. This section describes other

characteristics of the biological community that

must be considered in developing a Plan.

Algae

The algae, or phytoplankton, community forms the

foundation of the aquatic ecosystem and are the

first link in the aquatic food chain. The algae in

your lake can be used as indicators of the overall

nutrient status of your lake and the likelihood of

nuisance algae blooms. Certain algae, such as the

blue-green algae (a.k.a. cyanobacteria), are characteristic of nutrient enrichment. Since algae and

some aquatic plants both compete for dissolved

nutrients, in certain cases, algae problems may

increase if aquatic plants are removed. In other

words, fewer weeds allow the algae to have a bigger share of the nutrient pie. As a result, the algae

may flourish and create their own problems.

It is important to note that management for nuisance algae and management for nuisance aquatic

plants in a waterbody require different tactics. The

dominance of algae generally indicates a problem

with excessive nutrients in the water column that

could come from a variety of in-lake or offshore

sources. Algae control usually necessitates both

internal and external controls. Aquatic plant control is primarily concerned with in-lake treatment

for long-term effectiveness. It may also be supplemented by watershed controls as a secondary aid.

The concentration of chlorophyll a in the water

column is an index of algae abundance.

Chlorophyll a is one of a family of pigments that

make green plants green. It is the molecule that

captures the energy in light and transfers it to a

chemical form that provides the fuel for the entire

ecosystem. High chlorophyll a concentrations in

lake water indicate high algae densities, which

influences the light available for aquatic plant

growth.

Zooplankton

The zooplankton are microscopic aquatic animals

that graze on the algae present in the water.

Zooplankton graze algae like cows eat grass. High

zooplankton densities can reduce algae abundance

and result in high water clarity that permits aquatic

weeds to proliferate. The efficiency of zooplankton

grazing is dependent upon the relative size of the

algae and zooplankton. Large zooplankton are the

most efficient grazers, but they also look like big

juicy steaks to hungry fish.

Fish

There is a fine balance between the algae, zooplankton and fish in your lake. Many small fish

depend upon zooplankton for food. If zooplankton

populations are reduced by the fish, algae can

grow unchecked. Using the cow/grass analogy, if

wolves (fish) eat the cows (zooplankton), the grass

(algae) grows tall. If the wolves are eliminated by

hunting (big fish eat little fish), the cow population

increases, and the grass is short. Since algae determines light penetration of the water, changes in the

fish community can affect aquatic weed growth in

your lake.

Many lakes in Oregon are stocked with catchablesize trout. Introduction of many large fish into your

lake can have a ripple effect all the way down the

food chain, and can affect aquatic weed distribution and growth. The reverse is also true; changes

in the aquatic plant community due to your control

and management activities, can affect the fish population. Information on the native and stocked fish

in your lake can be obtained from the Department

of Fish and Wildlife.

Wildlife

Your lake may serve as a resource for a variety of

waterfowl and wildlife. Some waterfowl feed on

aquatic plants, while birds of prey, like eagles and

osprey, may fish in a lake or river. Muskrats,

IAVMP Manual 

C-7

Appendix C

v10.99
IAVMP Manual 

C-8

Appendix C

v10.99

beavers, otters, deer, and other animals may be residents or visitors. Your management activities may

alter the habitat quantity or quality available for

wildlife. A seasonal census of wildlife utilization

of the lake should be included in a Plan. Local residents and the Department of Fish and Wildlife are

good sources of information on the kinds and numbers of wildlife that depend upon your lake.

Shoreline Use

Your examination and characterization of the

watershed will provide some information on land

use along the shoreline. A more detailed look at the

shoreline is necessary to evaluate the feasibility of

some aquatic-plant management techniques. Some

herbicides cannot be used near drinking water

intakes; others require a waiting period before the

water can be used for irrigation purposes. In addition, you may identify areas that could be a source

of nutrients to the lake (e.g., failing septic systems

and heavily-fertilized lawns) and contribute to

water quality problems (see previous section on

Point and Nonpoint Pollutant Sources).

Outlet Control And Water Rights

What you do in your lake may effect water users

downstream and you must consider their water

rights. Lake drawdown and subsequent refilling

would affect flow below the outlet. Would altering

flow affect someone’s water rights or fish habitat

downstream? Would herbicide use affect downstream uses? Water level manipulation requires

some type of outlet structure. Who controls the

outlet structure and lake water level? Are they willing to cooperate in your efforts to manage aquatic

vegetation?

It is important to note that certain water rights

and established in-stream flow rates are legally

protected and must be maintained.

Salmon species within the project watershed

require special consideration, especially with the

recent passage of the Oregon Plan for Salmon and

Watersheds (See Box at beginning of appendix). If

salmonids migrate through your lake, the management plan must accommodate their movements and

spawning and rearing activities. The Oregon

Division of State Lands can provide information

about outlet control. Information regarding salmon

use and movement into and out of your lake can be

obtained from the ODFW.

References and Resources on Lake, River and

Reservoir Monitoring and Ecology

• Nonpoint Source Pollution Assessment and

Management Program7

• The Lake and Reservoir Restoration Guidance 

Manual

• Citizen Lake Watch Program

• Volunteer Lake Monitoring: A Methods Manual

• A Citizen’s Guide to Understanding and 

Monitoring Lakes and Streams
APPENDIX D 

Aquatic Plant Control Methods
Blank IAVMP Manual
Physical Control Methods

Physical methods of aquatic plant control include:

• Hand-pulling

• Hand cutting

• Bottom barrier application (sediment covers)

• Water level drawdown

• Implementing watershed controls to reduce 

nutrient inputs

• Water column dyes

Each method will be briefly discussed in terms of

mode of action, effectiveness and duration of control, advantages, drawbacks, costs, and required

permits.

Hand Pulling

Principle

Hand-digging and removal of rooted, submerged

plants is an intensive treatment option. This

method involves digging out the entire plant (stem

and roots) with a spade or long knife and disposing

of plant residue on shore. In shallow waters less

than 3 feet, no specialized gear is required. In

deeper waters, hand removal can best be accomplished by divers using scuba or snorkeling equipment and carrying collection bags for disposal of

plants.

Control Effectiveness And Duration

Efficacy of plant removal depends on sediment

type, visibility, and thoroughness in removing the

entire plant, particularly the roots. A high degree

of control over more than one season is possible

where complete removal of the entire plant has

been achieved.

Advantages

The technique results in immediate clearing of the

water column of nuisance plants. The technique is

very selective in that individual plants are

removed. It is most useful in sensitive areas where

disruption must be kept to a minimum. Because

the technique is highly labor-intensive, it is most

appropriate for small-area, low plant density treatments. In these cases, the technique is very useful

for aggressive control of sparse or small pockets

of Eurasian watermilfoil. This method can also be

useful for clearing pondweeds or very small patches of water lilies from areas around docks and

beaches.

Drawbacks

The technique is time-consuming and costly, especially where contract divers may be used. Diver

visibility may become obscured by turbidity generated by swimming and digging activities. Also, it

may be difficult for the laborer to see and dig out

all plant roots. Environmental impacts are limited

to mostly short-term and localized turbidity

increases in the overlying water and some bottom

disruption.

Costs

Costs will vary depending on whether contract

divers or laborers are used, or if removal activities

are the result of volunteer efforts. In the case of

contract divers and dive tenders, expenses can run

upward of $500 to $2400/day with area covered

dependent on density of plants.

Permits

No permits are currently required for hand-pulling

aquatic plants. However, be sure to check with

your local jurisdiction or watershed council before

beginning any aquatic plant management activities

in a water body.

Hand Cutting

Principle

This technique is also a manual method, but differs

from hand-pulling in that plants are cut below the

water surface (roots generally are not removed).

Implements used include scythes, rakes, or other

specialized devices that can be pulled through the

weed beds by boat or several people. Mechanized

weed cutters are also available that can be operated

from the surface for small-scale control.

Control Effectiveness and Duration

Root systems and lower stems are often left intact.

As a result, effectiveness is usually short-term as

regrowth is possible from the uncut root masses.

IAVMP Manual 

D-1

Appendix D

v10.99
Duration of control is limited to the time it takes

the plant to grow to the surface from remnant root

systems.

Advantages

The technique results in immediate removal of nuisance submerged plant growth. Costs are minimal.

Drawbacks

Like hand-pulling, the technique is time-consuming. Visibility may become obscured by turbidity

generated by cutting activities. Also, since the

entire plant is usually not removed, this technique

does not result in long-term reductions in growth.

Environmental impacts are limited to mostly shortterm and localized turbidity increases in the overlying water and some bottom disruption. Cut plants

must be removed from the water.

Costs

Where volunteer efforts are employed, costs are

mostly limited to purchase of a cutting implement.

This can vary from under $100 for the Aqua Weed

Cutter (Sunrise Corp.) to over $1000 for the mechanized Swordfish (Redwing Products).

Permits

No permits are required for hand-cutting or raking

of aquatic plants. However, be sure to check with

your local jurisdiction or watershed council before

beginning any aquatic plant management activities

in a waterbody.

Bottom Barrier Application

(Sediment Covers)

Principle

Barrier material is applied over the lake bottom to

prevent plants from growing, leaving the water

clear of rooted plants. Bottom covering materials

such as sand-gravel, polyethylene, polypropylene,

synthetic rubber, burlap, fiberglass screens, woven

polyester, and nylon film have all been used with

varying degrees of success. Applications can be

made up to any depth, with divers often utilized

for deeper water treatments. Usually bottom conditions (presence of rocks or debris) do not impede

most barrier applications, although pre-treatment

clearing of the site is often useful.

C o n t rol Effectiveness and Duration

Bottom barriers can provide immediate removal of

nuisance plant conditions upon placement. Duration

of control is dependent on a variety of factors,

including type of material used, application techniques, and sediment composition. Elimination of

nuisance plant conditions for at least the season of

application has been demonstrated by synthetic

materials like Aquascreen and Texel. Where shortterm control is desired for the least expense, burlap

has been found to provide up to 2-3 years of relief

from problematic growth before eventually decomposing (Truelson14, 15). After satisfactory control

has been achieved (usually several months), some

synthetic barrier materials can be relocated to other

areas to increase benefits.

A d v a n t a g e s

Bottom barriers can usually be easily applied to

small, confined areas such as around docks, moorages or beaches. They are hidden from view and do

not interfere with shoreline use. Bottom barriers do

not result in significant production of plant fragments (critical for milfoil treatment). Bottom barriers are most appropriately used for localized, smallscale control where exclusion of all plants is desirable; where other control technologies cannot be

used; and where intensive control is required regardless of cost.

D r a w b a c k s

Depending on the material, major drawbacks to the

application of benthic barriers include some or all of

the following: high materials cost, labor- i n t e n s i v e

installation, limited material durability, possible suspension due to water movements or gas accumulation beneath covers, or regrowth of plants from

above or below the material. Periodic maintenance

of bottom barrier materials is required to remove

accumulations of silt and any rooting fragments. In

some situations, removal and relocation of barriers

may not be possible (e.g., natural fiber burlap does

decompose over time). Sediment covers can also

produce localized reduction in populations of bottom-dwelling organisms like aquatic insects.

IAVMP Manual

D-2

Appendix D

v10.99
Costs

Costs vary from approximately $0.30/sq. ft (Texel)

to $0.35/sq. ft (Aquascreen) for materials with an

additional $0.25-0.50/sq. ft for installation.

Locally, prices for rolled burlap material (available

in fabric stores, outlets) average from $0.15 to

$0.25/sq. ft for materials only.

Permits

Currently no permits are required by State agencies

for bottom barrier applications in freshwater systems. However, be sure to check with your local

jurisdiction or watershed council before beginning

any aquatic plant management activities in a waterbody.

Water Level Drawdown

Principle

Water level drawdown used for management of

aquatic plants involves exposing plants and root

systems to prolonged freezing and drying, or hot,

dry conditions to kill the plants. Drawdown for

plant control is usually performed during winter

months, although summertime drawdowns are

sometimes conducted.13 It’s use has been more

common in management of reservoirs and ponds

than in natural lakes.

Control Effectiveness and Duration

Aquatic plants vary in terms of susceptibility to

drawdown. Some aquatic plants can be permanently damaged after sufficient exposure, while others

are unaffected or even enhanced. Therefore, accurate identification of target species is critical before

considering this method. A summary of responses

of common aquatic plants to water level drawdown

is presented in Restoration and Management of

Lakes and Reservoirs.13 For Eurasian watermilfoil,

effects have been variable, partly because of the

species’ability to withstand low temperatures for

short periods of time as well as its resiliency and

tenacity. The mild, wet winters typical of Western

Oregon may not provide adequate freezing/drying

conditions to kill certain plants.

Advantages

In addition to controlling aquatic plant biomass,

drawing down the water level makes it possible to

use several other management procedures for

restoration or improvement. For instance, it can be

used for fish management, to repair structures such

as docks or dams, to facilitate localized dredging

or bottom barrier placement or to remove stumps

or debris. This technique can result in compaction

of certain types of sediments, such as mucky substrates and thus improve shoreline use. Decreasing

nearshore vegetation through drawdown can

reduce potential inputs of nutrients to the water

from seasonal dying of aquatic plants. Drawdown

can be used to attract waterfowl by enhancing

growth of certain emergent plants such as cattails

and bulrushes.13

Drawbacks

This technique is not species-selective; removal of

beneficial plant species may occur. Wetlands adjacent to the waterbody can be exposed with possible

negative impacts on both plant and associated animal communities. Prolonged drying and freezing

can decrease bottom-dwelling invertebrates that

could be important food sources for fish. Dissolved

oxygen levels may decline as a result of lowering

the water level with possible negative impacts on

fish and other aquatic organism. Recreational use

of the waterbody may be limited or unavailable

during the period of drawdown. Drawdown has not

proven effective in the coastal lowlands of the

Pacific Northwest. If summer or winter drawdown

is implemented for plant control, sediments must

become completely dry for a prolonged period of

time to kill plant roots.

Costs

If an outlet structure is located on the waterbody,

expenses should be minimal. Other costs would

include recreational losses (perhaps loss in tourism

revenue).

Permits

Most water level drawdown projects that release

through regulated outlet structures require approval

from Oregon Division of State Lands. In addition,

IAVMP Manual 

D-3

Appendix D

v10.99
if the project area is within a federal navigable

waterways system, it will be necessary to obtain a

permit from the U.S. Army Corps of Engineers.

Watershed Controls

Principle

The principle involves reducing sources of external

(outside) nutrient and sediment inputs by implementing watershed best management practices

(BMP’s). The idea is to shut off entry of growthstimulating nutrients (phosphorus and nitrogen) to

the waterbody by using prudent household and

yard care practices, as well as employing agricultural, forestry, construction and road maintenance

practices that minimize pollutant loadings in the

watershed. Common examples of homeowner

BMP’s include: maintaining septic systems, using

prudent lawn and garden fertilizing practices, and

disposing of yard litter by shredding or composting

well away from water’s edge. Use of watershed

controls is often implemented as part of a whole

lake/watershed management effort, which may

involve other in-lake aquatic weed control and/or

nutrient control measures. For a more complete

discussion on BMP’s, see The Lake and Reservoir

Restoration Guidance Manual.4

Control Effectiveness and Duration

If it has been demonstrated that excessive rooted

macrophyte growth is due to siltation and external

nutrient inputs and not to historically-enriched sediments, then appropriate watershed controls could

provide long-term control of nuisance aquatic plant

growth. But it will take many years to achieve this

because siltation has created suitable habitat for

plants to flourish, with an adequate supply of nutrients already contained in sediments.

Advantages

Watershed best management practices are wideranging and usually easy to perform. Since the

watershed and waterbody are interconnected, any

reduction in contaminant loading to a waterbody as

a result of BMP’s can maintain or extend effectiveness of separate in-lake controls.

Drawbacks

Employing BMP’s to correct nuisance aquatic

plant growth will not result in immediate, substantial growth reduction because habitat has already

been created that supports aquatic plant growth.

Consultation with lake management experts as to

underlying causes of poor water quality (nuisance

aquatic plant growth is often symptomatic of a

larger problem) can aid in avoiding such a mistake.

Costs 

Initiation of most homeowner BMP’s involves very

little expense to get started. Most of the effort

involves voluntary changes in behavior, such as

modifying product buying practices (go for less

packaging, more environmentally friendly products), conserving water, energy, and composting

where possible.

Permits

Permits are not usually required for initiation of

best management practices around shorelines. This

is especially true for property owners utilizing prudent household and yard management practices.

Water Column Dyes

Principle

The theory behind this technique is to suppress

aquatic plant growth by shading the plants from

sunlight needed for photosynthetic growth. Darkcolored dyes are applied to the water, which

reduces the amount of light reaching the submersed plants.

Control Effectiveness And Duration

Aquashade (Applied Biochemists, Inc.) is a commercial dye product available for applications in

closed systems (water bodies with no outflow).

According to the manufacturer, Aquashade is

apparently effective against Eurasian watermilfoil,

Hydrilla, Elodea, and various pond weeds, as well

as macroalgae Chara sp. and filamentous green

algae like Spirogyra spp. There are a number of

other pond dyes on the market that mimic

Aquashade in their shading effects. These products

are probably more effective in shallower water

IAVMP Manual

D-4

Appendix D

v10.99
bodies where dye concentrations can be kept up

and the loss of dye through dilution would be less.

Best results are obtained when the product is used

early in the growth season.

Advantages

Aquashade is reported to be non-toxic to humans,

livestock, and aquatic organisms. No special equipment is needed for application; it can be poured

into the water by hand from shoreline or boat. It

imparts a blue color to the water.

Drawbacks

Its use is limited to shallow water bodies with no

outflow. According to the manufacturer,

Aquashade is less effective when aquatic plant

growth is within 2 feet of the surface In this case

other methods of removal are recommended prior

to dye use. This can increase program costs considerably. Repeat dye treatments may be necessary

throughout the growth season. Aquashade should

not be used in drinking water supplies, in flowing

waters, or in chlorinated waters.

Costs

Costs for Aquashade are approximately $50/gallon,

which can be used to treat one acre of water at

average depth of 4 feet at the recommended dosage

of 1 ppm (part per million).

Permits

Currently no permits are required by State agencies

for water column dye applications in freshwater

systems. However, be sure to check with your

local jurisdiction or watershed council before

beginning any aquatic plant management activities

in a waterbody.

Mechanical Control Methods

Mechanical methods for aquatic plant control

include:

• Mechanical harvesting

• Weed Rolling

• Rotovation/cultivation (underwater bottom 

tillage)

• Diver-operated suction dredging

Mechanical Harvesting

Principle

Mechanical harvesting is considered a short-term

technique to temporarily remove plants interfering

with recreational or aesthetic enjoyment of a

waterbody. Harvesting involves cutting plants

below the water surface, with or without collection

of cut fragments for offshore disposal. To achieve

maximum removal of plant material, harvesting is

usually performed during summer when submersed

and floating-leafed plants have grown to the

water’s surface.

Conventional single-stage harvesters combine cutting, collecting, storing and transporting cut vegetation into one piece of machinery. Cutting

machines are also available which perform only

the cutting function. Maximum cutting depths for

harvesters and cutting machines range from 5 to

8.2 ft with a swath width of 6.5 to 12.1 ft. Cooke

et al.13 summarizes aquatic plant cutters and harvesters available in North America.

Control Effectiveness and Duration

Since harvesting involves physical removal and

disposal of vegetation from the water, the immediate effectiveness in creating open water areas is

quite apparent. The duration of control is variable.

Factors such as frequency and timing of harvest,

water depth, and depth of cut are suspected to

influence duration of control. Harvesting has not

proven to be an effective means of sustaining longterm reductions in growth of milfoil. Regrowth of

milfoil to pre-harvest levels typically occurs within

30 to 60 days, 24 depending on water depth and the

depth of cut.

Advantages

Harvesting is most appropriately used for large,

open areas with few surface obstructions. There is

usually little interference with use of the waterbody during harvesting operations. Harvesting also

has the added benefit that removal of in-lake plant

biomass also eliminates a possible source of nutrients often released during fall dieback and decay.

This is of important consequence in those water

IAVMP Manual 

D-5

Appendix D

v10.99
bodies with extensive plant beds and low nutrient

inputs from outside sources. Furthermore, harvesting can reduce sediment accumulation by removing organic matter that normally decays and adds

to the bottom sediments. Depending on species

content, harvested vegetation can be easily composted and used as a soil amendment. Mechanical

harvesting costs can be relatively low compared to

other physical/mechanical techniques.

Drawbacks

Cut plant material requires collection and removal

from the water. Harvesting creates plant fragments.

This is of great concern with Eurasian watermilfoil, given its ability to rapidly disperse by fragmentation. Harvesting can be detrimental to nontarget plants and animals (e.g., fish, invertebrates),

which are removed indiscriminately by the

process. Harvesting can lead to enhancement of

growth of opportunistic plant species that invade

treated areas. Capital costs for machine purchase

are high and equipment requires considerable

maintenance.

Costs

Harvesting program costs depend on factors such

as program scale, composition and density of vegetation, equipment used, skill of personnel, and sitespecific constraints. Detailed costs are not uniformly reported, so comparing project costs of one

program with another can be difficult. However,

average costs of local harvesting operations range

from $200/acre to $700/acre.

Permits

Currently, no permits are required by the State for

mechanical cutting operations for aquatic plant

control. However, you should check with your

local jurisdiction or watershed council to determine

if local regulations apply to mechanical cutting

activities in a waterbody.

Weed Rollers

Principle

Weed rollers control aquatic vegetation by agitating and compacting the lake sediments. The

method uses a commercially available, low voltage

power unit that drives a roller on the lake bottom

through an adjustable arc of up to 270 degrees. A

reversing action built into the drive automatically

brings the roller back to complete the cycle. Fins

on the rollers detach some plants from the soil,

while the rollers force other plants flat, gradually

inhibiting growth. Detached plants should be

removed from the water with a rake or gathered 

by hand to prevent them from rooting in other

locations.

Once the plants are cleared from the area, the

device can be used as little as once per week or

less to keep plants from recolonizing the area.

When not in use the roller should be parked under

the dock to prevent injury from accidental contact.

Control Effectiveness and Duration

Weed rolling can provide long-term vegetation

control to areas around docks and shorelines. After

the initial clearing of plants, the device will only

have to be used periodically in order to maintain

the clearing. Little maintenance is required on the

machinery which has a life of over five years.

Advantages

Weed rolling provides an inexpensive method of

controlling weeds in a small area particularly

around docks and adjacent open water.

Drawbacks

Weed rolling may disturb some bottom dwelling

animals and may interfere with fish spawning.

Weed rolling may cause plant fragmentation,

which may increase the spread of some invasive

weeds. When the cleared area is to be used for

activities such a swimming or wading, the rollers

can become an obstacle

Permits

Currently, no permits are required by the State for

weed rolling for aquatic plant control. However,

you should check with your local jurisdiction or

watershed council to determine if local regulations

apply to weed rolling activities in the waterbody.

IAVMP Manual

D-6

Appendix D

v10.99
Rotovation/Cultivation 

(Bottom Derooting)

Principle

Mechanical rotovation/cultivation are bottom

tillage methods that remove aquatic plant root systems. This results in reduced stem development

and seriously impairs growth of rooted aquatic

plants. Derooting methods were developed by

aquatic plant experts with the British Columbia

Ministry of Environment as a more effective milfoil control alternative to harvesting. Essentially

two types of tillage machinery have been developed. Deep water tillage is performed in water

depths of 1.5 to 11.5 ft using a barge-mounted

rototiller equipped with a 6-10 ft wide rotating

head. Cultivation in shallow water depths up to a

few meters is accomplished by means of an

amphibious tractor or modified WWII “DUCW”

vehicle towing a cultivator. Both methods involve

tilling the sediment to a depth of 4-6 in, which dislodges plants including roots. Certain plants like

milfoil have roots that are buoyant and float on the

surface where they can be collected. Treatments

are made in an overlapping swath pattern. Bottom

tillage is usually performed in the cold “off-season” months of winter and spring to reduce plant

regrowth potential. 

Control Effectiveness and Duration

Bottom tillage has been used effectively for longterm control of Eurasian watermilfoil where populations are well-established and prevention of stem

fragments is not critical. Single treatments using a

crisscross pattern have resulted in milfoil stem

density reductions of 80-97 percent in bottom

tillage treatments.16, 17 Seasonal rototilling in an

area is at least as effective as 3 to 4 harvests, and

where repeated treatments have occurred at the

same site over several years, carryover effectiveness may extend to greater than a year.

Advantages

A high percentage of entire plants (roots and

shoots) can be removed by bottom tillage methods.

Depending on plant density, carryover effectiveness of rototilling can persist for up to 2 to 3 years

without retreatment. Following treatment, rotovated areas in Washington and British Columbia have

shown increases in species diversity of native

plants, of potential benefit to fisheries. Fish are not

removed through rototilling as they are by harvesting operations. Unlike harvesting which is conducted during summertime when plant growth is

maximal, rototilling treatments for root removal

can be performed during “off season” months of

winter and spring. This results in no interference

with peak summer-time recreational activities.

Drawbacks

Bottom tillage is limited to areas with few bottom

obstructions and should not be used where water

intakes are located. Rototilling does create shortterm turbidity increases in the area of operation,

but increases are usually temporary with a rapid

return to baseline conditions often within 24

hours.13, 16 Since bottom sediments are disturbed,

short-term impacts on water quality and the benthic invertebrate community can occur.

16 Rototilling

is not advised where bottom sediments have excessive nutrient and/or metals concentrations, because

of potential release of contaminants into the overlying water. Rotovation is not species selective,

except by location, and can result in unintentional

removal of non-target plants. The method does

result in production of plant fragments, and is not

recommended for use in water bodies with new or

sparse milfoil infestations or where release of fragments is a concern. Timing restrictions may be

imposed to avoid interference with fish spawning

or juvenile use.

Costs

Bottom tillage costs vary according to treatment

scale, density of plants, machinery used and other

site constraints. Contract costs for rotovation in the

State of Washington range from $1000-1700/acre

depending on treatment size.

Permits

Rotovation and cultivation that disturbs more than

50 cubic yards of sediment requires a permit from

the Corps of Engineers and approval of the

Division of State Lands.

IAVMP Manual 

D-7

Appendix D

v10.99
Diver Operated Suction Dredging

Principle

Diver dredging was being used in the late 1970s in

British Columbia as an improvement to hand

removal of sparse colonies of Eurasian watermilfoil.13 The technique utilizes a small barge or boat

carrying portable dredges with suction heads that

are operated by scuba divers to remove individual

rooted plants (including roots) from the sediment.

Divers physically dislodge plants with sharp tools.

The plant/sediment slurry is then suctioned up and

carried back to the barge through hoses operated

by the diver. On the barge, plant parts are sieved

out and retained for later off-site disposal. The

water sediment slurry can be discharged back to

the water or piped off-site for upland disposal.

Control Effectiveness And Duration

Diver dredging can be highly effective under

appropriate conditions. Efficiency of removal is

dependent on sediment condition, density of aquatic plants and underwater visibility.

13 As it is best

used for localized infestations of low plant density

where fragmentation must be minimized, the technique has great potential for milfoil control.

Depending on local conditions, milfoil removal

efficiencies of 85-97% can be achieved by diver

dredging.17

Advantages

The method is species-selective and site-specific.

Disruption of sediments are minimized. Plant

pieces are collected and retained, and fragmentation spread is minimized (very important for control of milfoil). It can be used to cover areas larger

than practicable for hand digging or diver hand

removal, or where herbicides cannot be used.

Diver-dredging can be conducted in tight places or

around obstacles that would preclude use of larger

machinery.

Drawbacks

Diver-dredging is labor-intensive and expensive. In

dense plant beds, the utility of this method may be

much reduced and other methods (e.g., bottom barrier) may be more appropriate. Returning dredged

residue directly to water may result in some fragment loss through sieves. Where upland disposal

of dredged slurry is used, more specialized equipment and materials are required and the process is

much more costly. Short-term environmental

effects can include localized turbidity increases in

the area of treatment. Release of nutrients and

other contaminants from enriched sediments can

also be a problem. In addition, some sediment and

non-target vegetation may be inadvertently

removed during the process.

Costs

Dredging costs can be very variable, depending on

density of plants, equipment condition and transport requirements of dredged material. In addition,

the use of contract divers for dredging work is subject to stringent State regulations on certification,

safety and hourly wage payment, which can affect

total project cost. Costs range from a minimum of

$1200/day to upwards of $2400/day (with no

dredged material transport).

Permits

In the State of Oregon, use of suction dredging

does require a permit from the U.S. Army Corps of

Engineers (COE). Suction dredging of the substrate also requires approval from Oregon Division

of State Lands.

Biological Control Methods

Interest in using biocontrol agents for nuisance

aquatic plant growth has been stimulated by a

desire to find more “natural” means of long-term

control as well as reduce use of expensive equipment or chemicals. The possibility of integrating

biological controls with traditional physical,

mechanical, or chemical methods is an appealing

concept. While development and use of effective

biocontrol agents for aquatic plant management is

still in its infancy, potentially useful candidates

have been identified such as plant-eating fish or

insects, pathogenic organisms, and competitive

plants. Except for exotic species infestation, a realistic objective of biocontrol of aquatic vegetation is

not the eradication, but the reduction of target plant

IAVMP Manual

D-8

Appendix D

v10.99
species to lower, more acceptable levels. 13 More

importantly, control of nuisance plants using biological agents will be a gradual process, although

the effects should be long-lasting. Biocontrol

options for most submersed aquatic weeds are limited. Insects have been released for control of

Purple loosestife in Oregon with great success.

Conact the Oregon Department of Agriculture for

additional information on biocontrol of Purple

loosestife.

Triploid (Sterile) Grass Carp

Principle

Grass carp or white amur (Ctenopharyngodon idel -

la Val.) are exotic, plant consuming fish native to

large rivers of China and Siberia. Known for their

high growth rates and wide range of plant food

preference, these fish can control certain nuisance

aquatic plants under optimal circumstances.

Stocking rates are dependent on climate, water

temperature, type and extent of plant species and

other site-specific constraints. Sterile grass carp are

most appropriately used for high-intensity control

of submersed plants. Recent field studies in

Washington State have shown that use of grass

carp for maintenance of a desired moderate level

of vegetation has rarely been successful2. Grass

carp require a permit from the Oregon Department

of Fish and Wildlife (ODFW). Current rules prohibit grass carp in natural lakes and in reservoirs

greater than 10 acres. State fisheries personnel

with ODFW should be contacted for more information on specific use and stocking of grass carp

in State waters.

Control Effectiveness And Duration

Effectiveness of grass carp in controlling aquatic

weeds depends on feeding preferences that are

related to age, size and metabolism of the fish.

Feeding rates do appear to be temperature-dependent1.13 Triploid grass carp exhibit distinct food

preferences which apparently vary from region to

region in the U.S, and even from site to site within

a region. Recent laboratory and field studies in

Washington State have shown that some plant

species appear to be highly preferred, such as the

pondweeds, Potamogeton crispus, P. pectinatus

and P. zosteriformis; others were variably preferred, such as coontail, Ceratophyllum demersum,

and some plants were not preferred, such as watershield, Brasenia schreberi. Grass carp control

effectiveness and duration are site-specific. In general, management studies in Washington waters

indicate that substantial removal of vegetation by

sterile grass carp may not become apparent until 

3-5 years after introduction.

In the 1980s, triploid grass carp were introduced

into Devils Lake as an experimental control.

Recently, new grass carp rules were adopted that

allow the use of the fish in private lakes and reservoirs smaller than 10 acres, and in irrigation

canals. Because of uncertainty over possible reproduction, parasites and escape, and due to recent

concerns over endangered salmon species, the

State has maintained a prohibition on generalized

use of grass carp in freshwater systems.

Advantages

Depending on the problem plant species and other

site constraints, grass carp can achieve long-term

reductions in nuisance growth of vegetation,

although not immediately. In some cases, introduction of grass carp may result in improved water

quality conditions, where water quality deterioration is associated with dense aquatic plant

growth.12

Drawbacks

Since sterile grass carp exhibit distinct food preferences, they do not graze all plants equally well,

limiting their applicability. The fish may avoid

areas of the waterbody experiencing heavy recreational use, resulting in less plant removal. Plant

reductions may not become evident for several

years. Grass carp grazing is not recommended for

milfoil control, especially where other beneficial,

more palatable species are present. In fact, use of

grass carp could indirectly increase milfoil populations in a waterbody by selectively removing highly preferred native plants. 19

Overstocking of grass carp could result in eradicaIAVMP Manual 

D-9

Appendix D

v10.99
tion of beneficial plants and have serious impacts

on the overall ecology of the waterbody. Full ecological impacts of grass carp introductions in

Northwest waters are still being determined. An

escape barrier on the outlet (if present) is required

to prevent movement of fish out of the system and

avoid impacts on downstream non-target vegetation. Fish loss due to predation, especially by

ospreys and otters is possible. Grass carp are only

permitted in reservoirs less than 10 acres in size.

Costs

Based on the few large-scale grass carp implantations made in the State of Washington since 1990,

costs can range from approximately $50/acre to

$2000/acre, at stocking rates ranging from 5

fish/acre to 200 fish/acre and average cost of

$10/fish (range $7.50/fish to $15.00/fish).

Permits

A permit is required by Oregon Department of Fish

and Wildlife prior to grass carp introduction to a

waterbody. Grass carp introduction into lakes or

salmon-bearing waters is currently prohibited,

because of serious environmental and ecological

concerns. Grass carp may be used in irrigation

canals and private ponds for eradication of aquatic

plants following strict rules to prevent escape,

reproduction, and spread of disease.

Milfoil Weevils

Native weevils (Euhrychiopsis lecontei) have been

found to impact populations of Eurasian watermilfoil in lakes in the Northeastern United States. The

weevils have been found in Washington state, however none have been found in Oregon. The weevils

in Washington have not caused declines in milfoil

populations in Washington lakes. 

Principle

E. lecontei is a native weevil that appears to have

shifted its preferred host plant when Eurasian

watermilfoil invaded North America. Prior to the

Eurasian watermilfoil invasion E. lecontei is

thought to have eaten native milfoil species. The

instar larvae feed on the plant meristem while

older larvae bore into the stems and feed on the

cortical and vascular tissue. The adults eat some

stem tissue but primarily feed on leaves. There are

several companies that sell weevils for introduction. It is preferable to have an established population that can be nurtured to populations high

enough to provide some level of milfoil control.

Control Effectiveness and Duration

The efficacy of E. lecontei for control of Eurasian

watermilfoil is quite variable. Although weevil herbivory has been implicated in some declines in

milfoil populations, efforts to introduce the insects

for control have had mixed results. There is no

good evidence that stocking of the weevils will

result in milfoil control.

Benefits

The weevils are a native organism and therefore,

there are no stringent controls on introduction of

the insect.

Drawbacks

Dependable control cannot be achieved. The

method is still in the experimental development

stage. The cost of importing a control agent of

unknown effecacy may be prohibative.

Costs

There are several companies that market the

Middfoil® process using the weevil to control milfoil. The weevils alone cost one dollar each with

minimum lots of 1000. They are not sold without a

proper monitoring program and having a site suitability study completed.

Permits

An APHIS form 526 from the Department of

Agriculture is required to transport the weevils into

the state.

Chemical Control Methods

Historically, use of aquatic herbicides has been the

principal method of controlling nuisance aquatic

weeds in Oregon. While cost and target species

efficacy have been important factors in choosing

herbicides for use in management schemes, other

IAVMP Manual

D-10

Appendix D

v10.99
factors, such as ecological and environmental

impacts on aquatic plants, potential interaction

between the environment and management activities, enhanced efficacy of using a combination of

different methods have not been explicitly considered. A more prudent approach, one endorsed by

this manual, involves moving away from such a

dominant generalized practice and toward more

selective herbicide use following thorough review

of target effectiveness, as well as other environmental, economic, political and social implications.

The State of Oregon currently permits use of only

six aquatic herbicides to control aquatic weeds.

They are the systemic herbicides fluridone, 2,4-d

and glyphosate, the contact herbicides, endothall

and diquat, and certain copper compounds.

Systemic herbicides are absorbed by plant roots

and shoots, and translocated throughout the plant;

systemic herbicides are capable of killing the entire

plant, including roots and shoots. In contrast, contact herbicides kill the plant surface with which it

comes in contact, leaving roots and unaffected

leafy stems alive and capable of regrowth. These

six herbicides are reviewed in more detail below.

Another herbicide, the triethylamine salt formulation of triclopyr, has been tested for efficacy

against Eurasian watermilfoil in selected waters in

Washington State under an Experimental Use

Permit (EUP). Triclopyr is a systemic herbicide

and is described in more detail by Getsinger et al.22

and Netherland et al. 21 Preliminary results of 1991

applications in Pend Oreille River (Washington)

milfoil beds indicate high selectivity against milfoil, rapid onset of toxicity symptoms, and minimal

IAVMP Manual 

D-11

Appendix D

v10.99

Table D-1. Common Aquatic Weed Species And Susceptibility To Herbicides (Adapted

From Westerdahl And Getsinger, 1988)10

Emergent species

Phragmites spp. (reed)

Scirpus spp. (bulrush)

Typha spp (cattail)

Lythrum salicaria (purple loosestrife)

Floating species

Brasenia schreberi (watershield)

Eichhornia crassipes (water hyacinth)

Lemna minor (duckweed

Nuphar.luteum (spatterdock)

Nymphaea odorata (fragrant water lily) 

Submersed species

Ceratophyllum demersum (coontail)

Elodea canadensis (elodea)

Egeria densa (Brazilian elodea)

Hydrilla verticillata (hydrilla)

Myriophyllum spicatum(Eurasian watermilfoil)

Myriophyllum aquaticum (parrotfeather)

Potamogeton spp.(pond weeds)

* Dependent on species

Endothall

G

F

F

G

G

E

F

E

G

E

E

E

*

Glyphosate

G

E

E

G

F

E

E

F

Fluridone

G

G

E

G

G

G

G

G

G

G

G*

Copper 

G

Diquat

F

G

F

E

E

E

E

G

G

E

E

G

2,4-d

E

G

E

E

G

G

G

F

E

E

Excellent, Good, Fair
damage to non-target plant species. This herbicide

is still under study and is not permitted for general

use at this time in Oregon State waters. To learn

more about aquatic herbicides, see references 1

and 10 listed in Appendix F.

Fluridone

Principle

Fluridone, 1-methyl-3-phenyl-5-[3-trifluoromethyl)phenyl]-4(1H)-pyridinone, is a slow-acting, systemic type herbicide. Fluridone inhibits

plant growth by interfering with carotenoid pigment synthesis, leading to chlorophyll degradation

and characteristic whitening of leaves in treated

plants. Fluridone is available as the EPA-registered

herbicide SONAR®(SePro) for use in the management of aquatic plants in freshwater ponds, lakes,

reservoirs, and irrigation canals. It is formulated as

a liquid (SONAR 4AS) sprayed above or below

surface, and in controlled release pellets (SONAR

5P, SONAR SRP) spread on the water surface.

Fluridone is effectively absorbed and translocated

by both plant roots and shoots.10

Control Effectiveness And Duration

Fluridone demonstrates good control of a variety

of submersed and emergent aquatic plants, especially where there is little water movement. Its use

is most applicable for lake-wide or isolated bay

treatments to control a variety of exotic and native

species. Eurasian watermilfoil is particularly susceptible to the effects of fluridone. Typical fluridone injury symptoms include retarded growth,

“bleached” (white or pink discoloration) leaves,

and plant death. Effects of fluridone treatment

become noticeable 7-10 days after application,

with control of target plants often requiring 60-90

days to become evident. 10 Because of the delayed

nature of toxicity, the herbicide is best applied during the early growth phase of the target plant, usually spring-early summer.

Advantages

As a systemic herbicide, fluridone is capable of

killing roots and shoots of aquatic plants, thus producing a more long-lasting effect. A variety of

emergent and submersed aquatic plants are susceptible to fluridone treatment (See Table on species

susceptibility to herbicides). As a result of extensive human health risk studies, it has been determined that use of fluridone according to label

instructions does not pose any affect to human

health.1 Fluridone also has a very low order of toxicity to zooplankton, benthic invertebrates, fish,

and wildlife.

Drawbacks

Fluridone is a very slow-acting herbicide, and its

effects can sometimes take up to several months.

Because of the long uptake time needed for

absorption and herbicidal activity, fluridone is not

effective in flowing water situations. Because of

the potential for drift out of the treatment zone,

fluridone is not suitable for treating a defined area

within a large, open lake. The potential exists for

release of nutrients to the water column and consumption of dissolved oxygen from the decaying

plants. Non-target plants may be affected, as a

variety of plants do show degrees of susceptibility

to fluridone treatment. Mitigation of lost vegetation may be necessary. As fluridone-treated water

may result in injury to irrigated vegetation, there

are label recommendations regarding irrigation

delays following treatment. To protect drinking

water sources, it is recommended that no applications be made within 0.25 miles of a water intake.

Costs

Treatment costs (materials and application) by private contractor for any of the formulations range

from about $900 to $1400/acre, depending on scale

of treatment.

Permits

At this time no permits are required for the use of

aquatic herbicides. The labeling on the container

describes the proper use of the product.

2,4-D 

Principle

The term “2,4-d” (2,4-dichlorophenoxy) acetic acid

describes a family of chlorinated phenoxy acid

compounds with herbicidal properties.

IAVMP Manual

D-12

Appendix D

v10.99
Chlorophenoxy acid herbicides function as systemic growth regulators with hormone-like activity

at low concentrations and behave as a contact-like

herbicide at higher concentrations. 2,4-d is

absorbed by roots and shoots and readily translocated throughout the plant. Absorbed 2,4-d inhibits

cell division of new tissue and stimulates abnormal, non-symmetrical growth of mature plant tissue, resulting in total cell disruption and plant

death. Of the many 2,4-d formulations available,

the dimethylamine salt (2,4-d DMA) and the

butoxyethanol ester (2,4-d BEE) forms are most

commonly used. Liquid and granular formulations

are available. 2,4-d can be applied to quiescent or

slow-flowing systems and turbid water.

Control Effectiveness And Duration

Phenoxy herbicides are more selective for

broadleaf, dicot species, but some aquatic monocots (e.g., water hyacinth) are also susceptible.

Species of Myriophyllum (watermilfoil) can be

effectively controlled with 2,4-d formulations in

flowing and quiescent waters. Carry-over effectiveness of one year or more with a 50-75% reduction

in biomass was demonstrated in Eurasian watermilfoil areas of the Pend Oreille River receiving

two same season treatments of 2,4-d DMA

(Gibbons and Gibbons, 1985). Other aquatic plant

species like coontail (Ceratophyllum demersum)

and naiad (Najas spp.) are less susceptible to 2,4-d.

Initial symptoms of 2,4-d toxicity in susceptible

plants (stem elongation and curling, leaflet fusion)

are usually apparent within a week, with plant collapse and defoliation occurring due to tissue decay

within two weeks. Regrowth can occur within 4 to

5 weeks if roots are not killed.

Advantages

As a systemic herbicide, 2,4-d is capable of killing

roots and shoots of aquatic plants, thus producing a

more long-lasting effect. Ester formulations of 2,4-d

are generally more phytotoxic than amine forms.

Toxicity effects are fairly rapid, with control of

most target vegetation occurring within two weeks.

A variety of emergent and submersed aquatic

plants are susceptible to 2,4-d treatment (See Table

on species susceptibility to herbicides). Amine formulations of 2,4-d have a low order of toxicity to

zooplankton, benthic invertebrates, fish, and

wildlife.

Drawbacks

Ester formulations of 2,4-d are more toxic to fish

than the amine compounds. Greater toxicity effects

are apparent with both amine and ester forms of

2,4-d at lower pH (e.g., 6.5) than at higher pH conditions10 of the water. Because of the potential for

drift out of the treatment zone, 2,4-d is not suitable

for treating a defined area within a large, open

lake. The potential exists for release of nutrients to

the water column and consumption of dissolved

oxygen from the decaying plants. Non-target plants

may be affected, as a variety of plants do show

degrees of susceptibility to 2,4-d treatment.

Mitigation of lost vegetation may be necessary.

There are label restrictions delaying use of treated

waters for irrigation, spraying, livestock watering

and domestic uses of up to three weeks post-treatment.

Costs

Treatment costs (materials and application) by private contractor for any of the formulations range

from about $700 to $1000/acre, depending on scale

of treatment.

Permits

At this time no permits are required for the use of

aquatic herbicides. The labeling on the container

describes the proper use of the product.

Glyphosate

Principle

Glyphosate (N-(phosphonomethyl)glycine) is a

non-selective, broad spectrum herbicide used primarily for control of emergent or floating-leafed

plants like water lilies. Mode of action studies of

the herbicide indicate an interruption of biosynthesis of aromatic amino acids. Glyphosate is a systemic herbicide that is applied to the foliage of

actively growing plants. The herbicide is rapidly

absorbed by foliage and translocated throughout

plant tissues, affecting the entire plant, including

IAVMP Manual 

D-13

Appendix D

v10.99
roots. Glyphosate is formulated as RODEO® or

Pondmaster®(Monsanto) for aquatic application. 

Control Effectiveness And Duration

Glyphosate is effective against many emergent and

floating-leafed plants, such as water lilies (Nuphar

spp.) and purple loosestrife (Lythrum salicaria).

According to the manufacturer, RODEO is not

effective on submersed plants or those with most

of the foliage below water. The herbicide binds

tightly to soil particles on contact and thus is

unavailable for root uptake by plants. As a result,

proper application to emergent foliage is critical

for herbicidal action to occur. Symptoms of herbicidal activity may not be apparent for up to 7 days,

and include wilting and yellowing of plants, followed by complete browning and death.

Advantages 

As a systemic herbicide, glyphosate is capable of

killing the entire plant including roots, producing

long-term control benefits. Glyphosate carries no

swimming, fishing, or irrigation label restrictions.

Glyphosate dissipates quickly from natural waters,

with an average half-life of 2 weeks in an aquatic

system. The herbicide has a low toxicity to benthic

invertebrates, fish, birds and other mammals.

Drawbacks

As a non-selective herbicide, glyphosate treatment

can have an affect on non-target plant species susceptible to its effects. While the possibility of drift

through aerial application exists, it is expected to

be negligible if application is made according to

label instructions and permit instructions.

Costs

Treatment costs (materials and application) by private contractor for any of the formulations average

approximately $250/acre, depending on scale of

treatment.

Permits

At this time no permits are required for the use of

aquatic herbicides. The labeling on the container

describes the proper use of the product.

Endothall

Principle

Endothall is a contact-type herbicide that is not

readily translocated in plant tissues. Endothall formulations (active ingredient endothall acid, 7-

oxabicyclo[2,2,1]heptane-2,3-dicarboxylic acid)

are currently registered for aquatic use in Oregon

in either inorganic or amine salts. The compound is

a membrane active herbicide that inhibits protein

synthesis in plants. The dipotassium salt formulation is used for aquatic plant control, while the

mono-amine salt is used for control of aquatic

plants and algae. Aqueous or granular forms of the

dipotassium salt of endothall, Aquathol (Elf

Atochem), is permitted in State waters with stringent use restrictions on water contact, irrigation

and domestic purposes as per label restrictions.

Due to higher toxicity potential, the liquid amine

form Hydrothol-191 is not permitted for use in

fish-bearing waters in the state.

Control Effectiveness And Duration

As a contact herbicide, endothall kills only plant

tissues it contacts, usually the upper stem portions.

Thus, the entire plant is not killed. It is therefore

used primarily for short-term control of aquatic

plants. Duration of control is a function of contact

efficiency and regrowth from unaffected root

masses. Effective reductions in plant biomass can

range from a few weeks to several months. In

some circumstances, season-long control can be

achieved. Carryover effectiveness of endothall

treatments into the following growth season is not

typical.

Advantages

Contact herbicides like endothall generally act

faster than translocating herbicides such as fluridone; evidence of tissue death is often apparent in

1-2 weeks. There is usually little or no drift impact

from proper application of this product. Overall

costs of treatment are less than fluridone applications over the same area.

IAVMP Manual

D-14

Appendix D

v10.99
Drawbacks

Because the entire plant is not killed, endothall

produces only temporary reductions in aquatic

plant growth. As a variety of aquatic plants are

susceptible to endothall, non-target plant impacts

are possible. There are label restrictions on fish

consumption and non-food crop irrigation and

domestic use following treatment with endothall

formulations.

Costs

As with fluridone applications, endothall treatments vary with total area and dosage rate.

Average costs for a small to moderate area application can run between $500-700/acre.

Permits

At this time no permits are required for the use of

aquatic herbicides. The labeling on the container

describes the proper use of the product.

Diquat

Principle

Diquat (6,7-dihydrodipyrido(1,2- :2’,1’-c)

pyrazinediium dibromide) is a contact-type, nonselective herbicide that is minimally translocated in

plant tissues. The herbicide is readily absorbed by

foliage, but absorption by root systems is negligible due to rapid inactivation in bottom sediments.

Mode of action of the herbicide is rapid disruption

of cells and cellular functions by release of strong

oxidants. Diquat is currently registered for aquatic

use in Oregon in either a concentrated or less concentrated aqueous form. The concentrated formulation (Reward®

, 2 pounds diquat per gallon) is

labeled for use in lakes, ponds, canals, streams,

rivers and drainage ditches that are quiescent or

slow-moving, under a federal/state agency use

restriction. A less concentrated form (Weedtrine®)

is labeled without the above agency use restrictions

for non-flowing waters with no or negligible outflow or under control of product user.

Control Effectiveness And Duration

As a contact herbicide, diquat kills only plant tissues it contacts, usually the upper stem portions.

Thus, the entire plant is not killed. It is therefore

used primarily for short-term control of a wide

range of emergent, floating and submersed aquatic

plants. Duration of control is a function of contact

efficiency and regrowth from unaffected root systems or propagules. Effective reductions in plant

biomass can range from a few weeks to several

months. Efficacy is substantially reduced in turbid

water or mud-coated vegetation because of rapid

absorption by sediment particles.

Advantages

Contact herbicides like diquat generally act faster

than translocating herbicides such as fluridone;

evidence of tissue death is often apparent in less

than one week. There is usually little or no drift

impact from proper application of this product.

Diquat disappears rapidly from the water due to

quick uptake by plant foliage and rapid binding to

suspended particles and sediments. Overall costs of

treatment are less than fluridone applications over

the same area.

Drawbacks

Because the entire plant is not killed, diquat produces only temporary reductions in aquatic plant

growth. As a variety of aquatic plants are susceptible to diquat, non-target plant impacts are possible.

There are label restrictions on water used for animal consumption, crop spraying and irrigation, and

domestic use for up to 14 days following treatment

with diquat formulations.

Costs

As with fluridone applications, diquat treatments

vary with total area and dosage rate. Average costs

for a small to moderate area application can run

between $600-1000/acre.

Permits

At this time no permits are required for the use of

aquatic herbicides. The labeling on the container

describes the proper use of the product.

Copper Chelates

Principle

Copper has a long history of use as an algaecide,

but has also shown effectiveness in controlling

IAVMP Manual 

D-15

Appendix D

v10.99
IAVMP Manual

D-16

Appendix D

v10.99

higher aquatic plants (e.g., hydrilla). Copper is an

essential element for plant growth. High concentrations of copper can lead to inhibition of photosynthesis and plant death. In order to maintain effective concentrations of the copper ion in solution, a

number of chelated or complexed forms of copper

have been developed. These complexed copper

compounds are much more effective herbicides

than copper sulfate, and are also less toxic to fish.

Control Effectiveness and Duration

The effectiveness of complexed copper compounds

is enhanced by warm temperatures and sunlight,

conditions that stimulate copper uptake by sensitive plants. In addition, uptake and toxicity is higher in young, rapidly growing plants, although even

mature plants such as hydrilla, Brazilian elodea,

and milfoil can be killed, and complexed copper

can effectively reduce large standing crops of these

species even in late summer.

27 The effect of treatment can be observed within 10 days, with full

effects manifested in 4 to 6 weeks. Depending on

timing of the initial treatment and regrowth rates a

second treatment, after about 12 weeks, may be

necessary for full season control.

Advantages

Costs of copper treatment are low relative to other

herbicides for submersed plant control. There are

no use restriction following treatment; complexed

copper can even be used in potable water supplies.

Drawbacks

Copper is persistent in the environment. Applied

copper eventually becomes bound to organic materials and clay particles and is deposited in the sediment. Yearly application of copper to lakes can

result in elevated copper concentrations in sediments. Although the bioavailability and toxic

effects of sediment-bound copper is unknown, the

toxicity of the copper ion to fish is higher in soft

than in hard water. Copper treatments should not

be made in waters with pH less than 6.0 due to

increased potential for formation of copper ion and

subsequent toxicity to fish10.

Costs

As with other herbicides, costs of copper treatment

vary with area treated and dosage. Costs generally

run between $120 and $340 per acre.

Permits

At this time no permits are required for the use of

aquatic herbicides. The labeling on the container

describes the proper use of the product. Liability

issues are an important consideration when using

herbicides. Some herbicides may only be applied

by a licensed applicator. It is highly recommended

that a licensed applicator do all herbicide applications.
APPENDIX E 

REFERENCES AND RESOURCES
Blank IAVMP Manual 
IAVMP Manual Appendix E

v10.99 E-1

A) Department of Agriculture (ODA)

Noxous Weed Program

635 Capitol St NE

Salem OR 97301-2532

(503) 986-4621

http://www.oda.state.or.us

Maintains a list of noxious weeds and assists in their control and erradication.

B) Division of State Lands (DSL)

Western Regional Manager

775 Summer St NE

Salem OR 97301-1279

(503) 378-3805

http://statelands.dsl.state.or.us

The permitting authority for aquatic plant control methods in all waters of the state.

C) Army Corps of Engineers (COE)

PO Box 2946

Portland OR 97208

(503) 808-4340

http://www.nwp.usace.army.mil

Controls all activities in navagable waters in Oregon. 

Provides permits for dredging and dredge material discharge.

D) Oregon Watershed Enhancement Board (OWEB)

255 Capitol Street NE 3rd floor

Salem OR 97310-0203

(503) 378-3589 Ext 827

Oregon Plan Information

http://www.oregon-plan.org

OWEB Information

http://4sos.org/group.gweb.html

Supports the work of watershed councils and awards grant funds for watershed restoration activities.

E) Oregon Department of Environmental Quality (DEQ)

Northwest Regional Office

2020 SW 4th ave. #400

Portland OR 97201

(503) 229-6945

http://www.deq.state.or.us

Responsible for permitting herbicides for use in Oregon lakes and reservoirs. Has permitting/certifica -

tion authority for Sections 402 (NPDES) and 401 (water quality certification) of the Clean Water Act.

Agencies and Organizations
Appendix E IAVMP Manual 

E-2 v10.99

F) Natural Heritage Program

The Nature Conservancy

821 SE 14th Ave

Portland OR 97214-2531

(503) 731-3070 x335 or x338

http://www.heritage.tnc.org/nhp/us/or

Maintains current listing of State endangered, threatened, sensitive plants, as well as high quality native

plant communities and wetlands.

G) Oregon Department of Fish and Wildlife (ODFW)

PO Box 59

Portland OR 97208

(503) 872-5255 ext. 5587

http://www.dfw.state.or.us

Processes fish planting permits; Manages and interprets data on wildlife species of concern in the State.

Also contact regional offices.

H) Oregon Lakes Association

PO Box 345

Portland OR 97207-0345

(503)725-3833

http://www.esr.pdx.edu/pub/ola

To promote the understanding, protection, thoughtful and responsible management of lakes and 

watersheds in Oregon.

I) North American Lake Management Society (NALMS)

One Progress Boulevard, Box 27

Alachua, FL 32615

(904) 462-2554

http://www.nalms.org

NALMS is a non-profit, volunteer organization that attempts to forge partnerships among citizens,

scientists, and professionals to foster the management and protection of lakes and reservoirs

J) PSU Center for Lakes and Reservoirs

Environmental Biology

PO Box 750

Portland OR 97207

(503) 725-3833

The Center for Lakes and Reservoirs has a task of studying the impact of non-native aquatic species on

the health of Oregon lakes.
IAVMP Manual Appendix E

v10.99 E-3

1) Washington Department of Ecology. 1992. Aquatic Plant Management Program for Washington 

State. Final Supplemental Environmental Impact Statement and Responsiveness Summary Vol. 1, 

January, 1992.

2) Hotchkiss, Neil. 1972. Common Marsh, Underwater & Floating-leaved Plants of the United States 

and Canada. Dover Publ., New York. 235 pp.

3) Anon. 1976. Making Aquatic Weeds Useful: Some Perspectives For Developing Countries. 

National Academy of Sciences, Washington, D.C. 174 pp.

4) U.S. Environmental Protection Agency. 1988. The Lake and Reservoir Restoration Guidance 

Manual, First Ed. Prepared by North American Lake Management Society. EPA 440/5-88-002.

5) North American Lake Management Society. 1989. NALMS Management Guide 

for Lakes and Reservoirs. Alachua, Florida. 42 pp.

6) Michaud, J.P. 1991. A Citizen's Guide to Understanding and Monitoring Lakes and Streams. 

Prepared for Puget Sound Water Quality Authority. 66 pp.

7) Washington Department of Ecology. 1989. Nonpoint Source Pollution Assessment and 

Management Program. No. 8817.

8) Marine Science Society of the Pacific Northwest. 1991. Puget SoundBook. Prepared for the 

Puget Sound Water Quality Authority. 47 pp.

9) U.S. Environmental Protection Agency. 1991. Volunteer Lake Monitoring: A Methods Manual. 

EPA 440/4-91-002.

10) Westerdahl, H.E. and K.D. Getsinger. 1988. Aquatic Plant Identification and Herbicide Use Guide, 

Vol. II: Aquatic Plants and Susceptibility to Herbicides. Technical Report A-88-9, U.S. Army 

Engineer Waterways Experiment Station, Vicksburg, Miss.

11) Weinmann, F., M. Boule, K. Brunner, J. Malek, and V. Yoshino. 1984. Wetland Plants of the Pacific 

Northwest. Prepared for U.S. Army Corps of Engineers, Seattle District. 85 pp.

12) Thomas, G.L., J.D. Frodge, S.A. Bonar, and G.B. Pauley. 1990. An Evaluation of Triploid Grass 

Carp Grazing on Ponds and Lakes of the Pacific Northwest. Washington Cooperative Fishery 

Research Unit, Univ. of Washington, Seattle, Washington. Fifth Progress Report prepared for 

Washington Department of Ecology.

13) Cooke, G.D., E.B. Welch, S.A. Peterson, and P.R. Newroth. 1993. Restoration and Management of 

Lakes and Reservoirs, 2nd Ed. Lewis Publishers, Boca Raton, FL. 548 pp.

14) Truelson, R.L. 1985. Assessment of the 1984 Eurasian Water Milfoil Control Program in Cultus 

Lake. Water Management Branch Rep. No. 3308. British Columbia Ministry of Environment.

15) Truelson, R.L. 1989. Use of Bottom Barriers to Control Nuisance Aquatic Plants. Water 

Management Branch Rep. British Columbia Ministry of Environment.

References
Appendix E IAVMP Manual 

E-4 v10.99

16) Gibbons, M.V., H.L. Gibbons, and R. E. Pine. 1987. An Evaluation of a Floating Mechanical 

Rototiller for Eurasian Water Milfoil Control. No. 87-17. Washington Department of Ecology.

17) Maxnuk, M. 1979. Studies on Aquatic Macrophytes. Part XXII. Evaluation of Rotavating and 

Diver Dredging for Aquatic Weed Control in the Okanagan Valley. Water Investigations Branch Rep. 

No. 2823, British Columbia Ministry of Environment.

18) Sanders, L, J.J. Hoover, and K.J. Killgore. 1991. Triploid Grass Carp as a Biological Control of 

Aquatic Vegetation. Aquatic Plant Control Research Program, Vol A-91-2. U.S. Army Corps of 

Engineers Waterways Experiment Station.

19) Pauley, G.B. and G.L. Thomas. 1987. An Evaluation of the Impact of Triploid Grass Carp 

(Ctenopharyngodon idella) on Lakes in the Pacific Northwest. Washington Cooperative Fishery 

Research Unit, Univ. of Washington, Seattle, Washington. Third Progress Report prepared for 

Washington Department of Ecology.

20) Pauley, G.B. and G.L. Thomas. 1988. The Effects of Triploid Grass Carp Grazing on Lakes in the 

Pacific Northwest. Washington Cooperative Fishery Research Unit, Univ. of Washington, Seattle, 

Washington. Fourth Progress Report prepared for Washington Department of Ecology.

21) Netherland, M.D. and K.D. Getsinger. 1992. Efficacy of Triclopyr on Eurasian Watermilfoil: 

Concentration and Exposure Time Effects. J. Aquat. Plant Manag. 30: 1-7.

22) Getsinger, K.D., E.G. Turner, and J.D. Madsen. 1992. Field Evaluation of the Herbicide triclopyr 

for managing Eurasian Watermilfoil. Aquat. Plant Contr. Res. Prog. Bull. A-92-3. U.S. Army 

Engineer Waterways Experiment Station, Vicksburg, Mississippi.

23) Wetzel, R.G. 1983. Limnology, Second Edition. W.B. Saunders Company, New York, New York.

24) Perkins, M.A. and M.D. Sytsma. 1987. Harvesting and Carbohydrate Accumulation in Eurasian 

Watermilfoil. J. Aquat. Plant Manag. 25: 57-62.

25) Hitchcock, C.L. and A. Cronquist. 1973. Flora of the Pacific Northwest. Univ. of Washington 

Press, Seattle. 730 pp.

26) Anon. Starting and Building an Effective Lake Association. North American Lake Management 

Society, Alachua, Florida. 43 pp.

27) Anderson, L.W.J. In press. Potential copper uptake by aquatic plants. Proceedings, Workshop on the 

Bio-Availability and Toxicity of Copper. University of Florida Center for Aquatic Plants.

28) Bortleson, G.C., Dion, N.P., McConnell, J.B. and L.M. Nelson. 1976. 

Reconnaissance Data on Lakes in Washington, Vols. 1-7. Washington Department of Ecology in 

Cooperation with the U.S. Geological Survey.

29) Bortleson, G.C., et al. 1974-1976. Data on Selected Lakes in Washington, Parts 1-4. Washington 

Department of Ecology in Cooperation with the U.S. Geological Survey.

30) Guard, B. Jennifer. 1995. Wetland Plants of Oregon and Washington. Lone Pine Publications, 

Redmond, WA. 239pp.
IAVMP Manual Appendix E

E-5

31) Cooke, Sarah S. (ed.). 1997. A Field Guide to the Common Wetland Plants of Western Washington 

and Northwest Oregon. Seattle Audubon Society, Seattle, WA. 417pp.

32) Oregon Plan for Salmon and Watersheds Monitoring Team. 1999 Water Quality Monitoring 

Technical Guide Book. July 1999

v10.99