Volunteer Lake Monitoring
Office of Water
Volunteer Lake Monitoring
EPA440-4-91-002
Contents
Foreword
Executive Summary
Chapter 1
Introduction
1.A Purpose of this Manual
1C Planning a Monitoring Program
Chapter 2
Focusing on a Lake Condition
2.B Alaae
2.D Dissolved Oxygen
2.E Other Lake Conditions
Chapter 3
Monitoring Algae
3.A Algal Condition Parameters
3. B Where to Sample
3.C Where to Sample in the Water Column
3.D Frequency of Sampling
3.E Length of the Sampling Season
3.F How to Sample
3.G Notes on Equipment
Chapter 4
Monitoring Aquatic Plants
4.A Aquatic Plant Condition Parameters
4.B Sampling Considerations
4.C How to Sample
Chapter 5
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Monitoring Dissolved Oxygen
5.A Dissolved Oxygen Parameters
5.C How to Sample
Chapter 6
Monitoring Other Lake Conditions
6.A Monitoring Sedimentation
6.B Monitoring Suspended Sediment
6.C Monitoring Acidification
6.D Monitoring the Bacteria at Bathing Beaches
Chapter 7
Training Citizen Volunteers
7.A The Training Process
7.B Creating a Job Analysis
7.C Planning the Training
7.D Presenting the Training
7.E Evaluating the Training
7.F Follow-up Coaching, Motivation, and Feedback
Chapter 8
Presenting Monitoring Results
8.A Overview of Data Presentations
8.B Algae Results
8.C Aquatic Plant Results
8.D Dissolved Oxygen Results
Office of Water
Volunteer Lake Monitoring: A Methods Manual
Foreward and Acknowledgements
Foreword
The need to gather information on conditions in our Nation's lakes has never been greater. Local,
state, and Federal agencies, as well as private citizens, seek monitoring information for a variety of
educational, planning, and regulatory purposes. Unfortunately, public funding and staffing to
carry out water sampling activities have not always kept pace with this need.
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To fill this information gap, many state agencies have organized cost-effective programs that train
local citizens to monitor the quality of their lakes. Volunteer programs have been found to be of
enormous value to states, which can gain a baseline of useful information on lakes that might
otherwise have gone unmonitored. States also benefit from new partnerships with educated and
involved citizens who actively work to protect their lake resources.
Citizen volunteers benefit from monitoring programs as well. Volunteers learn about water
sampling, lake biology, and the impacts of land use activities. In gathering information about the
condition of their individual lakes, volunteers also often become involved in lake and watershed
management activities.
The experience of successful volunteer programs shows us that the spirit of stewardship and
teamwork engendered by these volunteer efforts is of great help in protecting our Nation's lakes
for future generations to use and enjoy. The U.S. Environmental Protection Agency recognizes
the value of these efforts and has developed this methods manual to provide a useful tool to
those who are involved, or would like to become involved, in lake monitoring activities.
Martha G. Prothro
Director, Office of Water
Regulations and Standards
U.S. Environmental Protection Agency
Washington, DC 20460
ACKNOWLEDGEMENTS
The EPA project officers were Alice Mayio and Margaret Kerr. The principal author was Jonathan
T. Simpson. JT&A, Inc. provided editorial support. Special thanks are extended to the many
reviewers who provided valuable comments on the content and organization of this manual.
The principal author wishes to thank Dr. Robert Carlson, Charles Fredette, Alice Mayio and
especially Dr. Harvey Olem for their contributions to this manuscript.
Layout/graphics (except where indicated): Jonathan T. Simpson.
cover art: candlewood lake, Connecticut
by Terri Talas (courtesy of Northeast Utilities).
Return to the Table of Contents
Office of Water
Volunteer Lake Monitoring: A Methods Manual
Executive Summary
Overview
Increasingly, State, local, and Federal agencies are finding that citizen volunteers are valuable
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partners in programs to monitor and protect our Nation's water resources. Among the most
developed and widespread of these volunteer programs are those that monitor existing or
potential lake pollution problems.
The U.S. Environmental Protection Agency (EPA) has supported the volunteer monitoring
movement since 1987 by sponsoring two national volunteer monitoring symposia, publishing a
newsletter for volunteers and a directory of volunteer organizations, developing guidance
manuals, and providing technical assistance. These activities have been designed to help State
and other agencies understand the value of volunteer monitoring programs, both as potential
sources of credible data and as catalysts for developing an educated and involved citizenry.
The EPA has developed this manual to present specific information on volunteer lake water
quality monitoring methods. It is intended both for the organizers of the volunteer lake monitoring
program, and for the volunteer who will be actually be sampling lake conditions. Its emphasis is
on identifying appropriate parameters to monitor and setting out specific steps for each selected
monitoring method. Careful quality assurance/quality control procedures are advocated
throughout this manual to ensure that the data collected by volunteers are useful to States and
other agencies.
This manual begins by summarizing the steps necessary to plan and manage a volunteer
monitoring program, including setting general goals, identifying the uses and users of collected
data, and establishing sound quality assurance procedures. Rather than addressing every
parameter and method that might be monitored by the citizen volunteer, this manual concentrates
special attention on three of the most common lake pollution problems: increased algal growth;
increased growth of rooted aquatic plants; and lowered or fluctuating levels of dissolved oxygen.
All three are common symptoms of human-induced (cultural) eutrophication. Other lake
conditions that can be monitored by volunteers are also briefly discussed including sedimentation,
turbidity, lake acidification, and bacteriological condition.
Increased Algal Growth
This manual discusses three parameters most commonly used by volunteer monitoring programs
to measure the algal condition of a lake: Secchi disk transparency (a measure of water clarity and,
indirectly, of algal density); chlorophyll a (a more reliable indicator of algal density); and total
phosphorus (a measure of water fertility). Ideally, all three should be measured in a monitor ing
program. Step-by-step instructions are provided on sampling procedures.
Increased Growth of Rooted Aquatic Plants
Three procedures are recommended for assessing the overgrowth of rooted aquatic plants:
mapping the distribution of plant beds in the lake; estimating the density of plants along a
transect line in a selected part of the lake; and collecting plant specimens for professional
identification. Specific procedures are outlined.
Lowered or Fluctuating Levels of Dissolved Oxygen
Dissolved oxygen conditions are best characterized by measuring the dissolved oxygen and
temperature profiles of the lake (measurements taken from the lake surface to the lake bottom at
set intervals).
In addition to discussing specific sampling methods and equipment, this manual outlines a
specific volunteer training process. Training the citizen volunteer is an essential component of a
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successful monitoring program. Time and resources should be budgeted up front to plan,
present, and evaluate volun teer training, both at the start of the program and as periodic
follow-up and "continuing education." The payoff includes: more effective, involved, and confident
volunteers; better data; and more efficient use of the coordinator's (and volunteer's) time and
energy.
This manual concludes with advice on how to present volunteer-collected data. After all, a
volunteer program is of little value if the generated data are not translated into information useful
both to the volunteers and to the managers of the program. Hints and examples are provided on
presenting data results to meet the needs and level of knowledge of the data users.
This manual attempts to provide a comprehensive overview of standard lake volunteer monitoring
methods. However, it cannot claim to cover every conceiv able approach. Methods and equipment
other than those described here may be perfectly acceptable and meet the needs of the programs
that employ them.
Reference documents and material from existing lake volunteer monitoring programs are cited at
the end of each chapter to provide the reader with addi tional detailed information on methods,
limnology, data quality considerations, and program planning. Anyone interested in establishing a
lake volunteer monitoring program is strongly encouraged to consult these references and to
evaluate the experiences, goals, and techniques of the many successful volunteer lake monitoring
programs already underway.
Return to the Table of Contents
Office of Water
Volunteer Lake Monitoring: A Methods Manual
Chapter 1: Introduction
1.A Purpose of this Manual
The purpose of this manual is to present methods for monitoring important lake conditions using
citizen volunteers. This information will be helpful to agencies, institutions, and private citizens
wishing to start new volunteer monitoring efforts, as well as those who may want to improve an
existing program. The citizen volunteer who uses these techniques will be able to collect reliable
data that can be used with confidence for a variety of resource management purposes.
This document is designed as a companion manual to a guide produced by the U.S.
Environmental Protection Agency (E PA) entitled Volunteer Water Monitoring: A Guide for State
Managers. The EPA guide describes the role of citizen volunteer monitoring in state programs and
discusses how a state monitoring program can best be organized and administered.
Copies of the EPA's Volunteer Water Monitoring: A Guide for State Managers may be obtained by
contacting:
U.S. Environmental Protection Agency
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Office of Wetlands, Oceans, and
Watersheds
Assessment & Watershed Protection Div.
WH-553
401 M Street, S.W.
Washington, D.C. 20460
Volunteer Lake Monitoring: A Methods Manual extends the concepts and procedures
developed by the EPA guide and puts them in a "how to do it" context specifically for volunteer
lake monitoring programs.
1.B Manual Organization
Volunteer Lake Monitoring: A Methods Manual is organized into eight chapters.
Chapter 1: Introduction
This chapter provides an overview for the manual and discusses planning a lake monitoring
program. Topics include setting general goals, identifying uses and users of the data, and
developing quality assurance and quality control procedures.
Chapter 2: Focusing on a Lake Condition
This chapter introduces the three lake conditions most suitable for volunteer monitoring: algae;
(rooted) aquatic plants; and dissolved oxygen. Other conditions that could be considered for
monitoring are also discussed.
Chapter 3: Monitoring Alaae
Chapter 4: Monitoring Aquatic Plants
Chapter 5: Monitoring Dissolved Oxygen
Chapter 6: Monitoring Other Lake Conditions
These four chapters identify monitoring parameters that can be used to characterize each of the
lake conditions introduced in Chapter 2. Sampling design issues discussed include where and
how often volunteers should sample. Procedures for sampling are also defined in a step-by-step
manner.
Chapter 7: Training Citizen Volunteers
This chapter defines a training process that can be used to educate volunteers on sampling
procedures. Included are sections on how to write a job description for volunteers and how to
plan, present, and evaluate volunteer training.
ChaoterS: Presenting Volunteer Monitoring Results
This chapter recommends ways to present the lake monitoring data results using graphs and
summary statistics.
CHAPTER 1
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1.C Planning a Monitoring Program
The steps necessary to plan and manage a successful volunteer monitoring program are well
covered in EPA's Volunteer Water Monitoring: A Guide for State Managers. Topics in this guide
include how to establish goals, identify data uses and users, assign staff responsibilities,
establish a pilot program, prepare a quality assurance plan, and fund a program.
The purpose of this companion manual is not to repeat material presented in the Guide for State
Managers but rather to provide specific information concerning the administration of a lake
monitoring program. To do this adequately, however, a few of the guide's key concepts need to
be highlighted in the context of planning a lake monitoring program.
Setting General Goals
Volunteers or agencies that begin a volunteer lake monitoring program face an almost bewildering
array of planning decisions. Therefore, EPA has set out certain guidelines to help in planning and
implementing volunteer programs.
As a first step, organizers of volunteer programs should establish their general goals. Are they
interested in providing credible information on water quality conditions to State and local
agencies? Or are they primarily interested in educating the public about water quality issues? Do
they wish to build a constituency of involved citizens?
All three goals can be achieved by a well-organized and maintained program, but it is important to
determine which of these goals is paramount. This methods manual is directed primarily to those
volunteer programs that seek to improve the understanding of lake conditions and protection
needs by supplementing State- collected water quality data with credible volunteer-collected data.
Identifying Data Uses
Early in the planning stage, organizers should identify how data collected by the lake volunteer
program will be used and who will use it. Data can be used to establish baseline conditions,
determine trends in water quality, or identify current and emerging problems.
Prospective users of volunteer-collected data include State water quality analysts, planners,
fisheries biologists, agricultural agencies, and parks and recreation staffs; local government
planning and zoning agencies; university researchers; and Federal agencies such as the U.S.
Geological Survey, U.S. Fish and Wildlife Service, U.S. E PA, and U.S. Department of Agriculture.
A planning committee made up of represen tatives from the identified data users should be
convened early in the development of a program.
Initially, the planning committee must make several important decisions in the development of a
volunteer monitoring program. Basically, the committee must decide:
• What the major goal of the program will be;
• What existing or potential lake condition will be the focus of monitoring;
• What sampling parameters should be used to characterize the selected lake condition;
• What procedures volunteers should use to sample each parameter;
• How volunteers will be trained; and
• How the results of monitoring will be presented.
Once the monitoring program is established, the planning committee should meet periodically to
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evaluate it, update objectives, and fine-tune activities. This review should ensure that the
volunteer monitoring efforts continue to provide useful information to those who need lake data.
Establishing Quality Assurance and Quality Control
Many potential users of volunteer data believe that only professionals can conduct sampling and
generate high quality results. This is not true. Given proper training and supervision, dedicated
volunteers can conduct monitoring activities and collect samples that yield high quality data. To
ensure that this occurs, any volunteer lake monitoring program that seeks to have its data used
must adopt effective quality assurance/quality control (QA/QC) responsibilities.
The planning of QA/QC procedures begins with the development of data quality objectives. The
objectives are defined by data users and establish the uncertainty that can be tolerated for their
specific purposes. There are five major areas of uncertainty that should be evaluated when
formulating data quality objectives.
• Accuracy is the degree of agreement between the sampling result and the true value of the
param eter being measured. Accuracy is most affected by the equipment and the procedure
used to measure a sample parameter.
• Precision, on the other hand, refers to how well you are able to reproduce the data result
on the same sample (regardless of accuracy). Human error in sampling techniques plays an
important role in estimating precision.
• Representativeness is the degree to which the collected data accurately and precisely
represent the lake condition being measured. It is most affected by sample site location. For
example, if the monitoring objective
• Completeness is a measure of the amount of valid data obtained versus the amount
expected to be obtained as specified by the original sampling design objec tives. It is
usually expressed as a percentage. For example, if 100 samples were scheduled, but
volunteers only sampled 90 times because of bad weather, broken equipment, and so forth,
the completeness record would be 90 percent.
• Comparability is very important to the manager of a citizen monitoring program because it
represents how well data from one lake can be compared to data from another. As part of a
statewide or regional report on the volunteer monitoring program, most managers compare
one lake to another. It is vital, therefore, that sampling methods and procedures are the
same from lake to lake.
When forming data quality objectives, the planning committee must also examine the program
budget. Sophisticated analysis of some param eters (yielding high precision and accuracy)
usually comes at higher costs in terms of equipment, procedures, laboratory fees, agency time,
and citizen training. These higher costs may be worthwhile if the program is oriented toward
supplementing agency data collection.
For programs oriented more toward public education and participation, the use of less sensitive
equipment and procedures may be in order. In this case, budget money could be better spent for
public awareness materials and supporting an increase in citizen monitors. An efficient sampling
design is one that balances cost components with acceptable levels of uncertainty in context with
program goals and objectives.
It is important to be aware that EPA requires that all its national program offices, regional offices,
and laboratories participate in a centrally planned, directed, and coordinated Agencywide QA/QC
program. As stated in the EPA document, Volunteer Water Monitoring: A Guide for State
Managers , "This effort also applies to efforts carried out by the States and interstate agencies
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that are supported by EPA through grants, contracts or other formalized agreements."
The EPA QA program is based upon EPA Order 5360.1, "Policy and Program Requirements to
Implement the Quality Assurance Program, "which describes the policy, objectives, and
responsibilities of all EPA program and regional offices.
EPA Order 5360.1 also requires State monitoring programs supported by EPA grants to prepare
Quality Assurance Project Plans. There are 16 major elements contained in a Quality Assurance
Project Plan.
1. Title Page: includes the name of the project officer, the immediate supervisor, the funding
organization and others with major responsibility for the project.
2. Table of Contents: lists the included elements and appendices in the report.
3. Project Description: states the purpose of the project.
4. Project Organization and Responsibility : identify the structure or organization
responsible for the implementation of the program.
5. QA Objectives: list the QA objectives for each major measurement parameter for precision,
accuracy, representativeness, completeness, and comparability.
6. Sampling Procedures: describe how parameters are monitored.
7. Sample Custody: identifies chain of custody for field sampling and laboratory operations.
8. Calibration Procedures and Frequency : describe methods for maintaining accuracy and
preci sion of sampling equipment.
9. Analytical Procedures: document how parameters are analyzed.
10. Data Reduction, Validation, and Reporting : address the activities involved in an overall
data management plan.
11. Internal Quality Control Checks : discuss quality control procedures.
12. Performance and System Audits : evaluate all components of the measurement system
including equipment, personnel, and procedures.
13. Preventive Maintenance: ensures there are no gaps in the data gathering activities.
14. Specific Routine Procedures Used to Assess Data Precision, Accuracy, and
Completeness: identify the methods to calculate precision and accuracy and how
calibration and comparability studies are undertaken.
15. Corrective Action: identifies limits for data acceptability and corrective procedures if data
are found unacceptable.
16. Quality Assurance Reports: describe the format and schedule for the submission of
reports that assess data accuracy, precision and completeness, the results of QC sessions
and audits, and any significant QA problems with recommended solutions.
Data documentation is another crucial aspect of QA/QC procedures. Careful and thorough
documentation of any data base used to store and manage volunteer data ensures that it can be
used with confidence. Appropriate documentation is especially important if data are to be entered
into a State (or other formal) data base.
Volunteer Water Monitoring: A Guide for State Managers provides additional specific direction on
developing data quality objectives, quality assurance project plans, and data documentation files.
Chapter 8 of this manual further discusses how to analyze and present volunteer data.
References
U.S. Environmental Protection Agency. 1980. Guidelines and Specifications for Preparing Quality
Assurance Project Plans. QAMS-005/80. Washington, DC.
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. 1984. The Development of Data Quality Objectives. Washington, DC.
. 1984. Guidance for Preparation of Combined Work/Quality Assurance Project Plans for
Environmental Monitoring. OWRS QA-1. Washington, DC.
. 1988. Guide for Preparation of Quality Assurance Project Plans for the National
Estuarine Program, Interim Final. EPA 556-2-88-001. Washington D.C.: Off. Mar. Estuarine Prot.,
Washington, DC.
. April 1990. Rhode Island Sea Grant College Program. National Directory of Citizen
Volunteer Environmental Monitoring Programs . EPA 440/9-90-004. Off. Water, Washington, DC.
. August 1990. Volunteer Water Monitoring: A Guide for State Managers. EPA
440/4-90-010. Off. Water, Washington, DC.
Return to the Table of Contents
Office of Water
Volunteer Lake Monitoring: A Methods Manual
Chapter 2: Focusing on a Lake Condition
2.A Introduction
It is beyond the scope of any monitoring program to sample for every condition that can be found
in a lake. Therefore, an initial task is to decide where to focus sampling efforts. This chapter
discusses lake conditions that make good candidates for citizen monitoring.
Of all the water quality issues facing lakes nationwide, it is those conditions associated with a
phenomenon known as eutrophication that cause the greatest concern among lake users.
Eutrophication is a term used to describe the aging of a lake. This aging process results from the
accumulation of nutrients, sediments, silt, and organic matter in the lake from the surrounding
watershed.
Eutrophication can be accelerated when human activity occurs in the watershed. If proper
controls are not in place, pollutants from agricultural, urban, and residential developments can
easily be carried into lakes and their tributaries.
Symptoms of human-induced (or cultural) eutrophication are:
• increased algal growth (stimulated by increased supply of nutrients);
• increased rooted aquatic plant growth (stimulated by the increased supply of nutrients as
well as the creation of additional shallow growing areas via the accumulation of sediments,
silt and organic matter); and
• lower dissolved oxygen concentrations in all or parts of the lake (as a result of increased
plant respiration and the decomposition of organic matter by bacteria and other
microorganisms. This lack of oxygen can kill fish and other aquatic life).
The emphasis of this manual is on how citizen volunteers can monitor one or more of the lake
conditions listed above. These conditions are usually considered symptomatic of cultural
eutrophication.
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Although related, each condition nevertheless has a unique set of parameters that characterize its
attributes. It is important to remember that sampling for one condition will not necessarily yield
information about another. If, for example, a lake has an aquatic plant problem, a monitoring
program that focuses on algae will not provide the necessary answers to solve that problem.
The reader should be aware that there are several other lake conditions that could be a potential
focus for a citizen monitoring program. Four notable candidates are:
• sedimentation on the lake bottom (reduction of water depth);
• sediment turbidity (reduction of water clarity as a result of suspended sediment);
• lake acidification; and
• bacterial pollution of bathing beaches.
Each of these conditions has the potential to severely affect the water quality and recreational use
of a lake. In many lakes, they are monitored by agency staff or contracted professionals. These
lake conditions can, how ever, be monitored by volunteers.
For this reason, they also will be briefly discussed in this manual.
The following sections provide background on each of the lake conditions that could be
considered candidates for a citizen monitoring program.
2.B Algae
Algae are photosynthetic plants that contain chlorophyll and have a simple reproductive structure
but do not have tissues that differentiate into true roots, stems, or leaves. They do, however, grow
in many forms. Some species are microscopic single cells; others grow as mass aggregates of
cells (colonies) or in strands (filaments). Some even resemble plants growing on the lake bottom.
The algae are an important living component of lakes. They:
• convert inorganic material to organic matter through photosyn thesis;
• oxygenate the water, also through photosynthesis;
• serve as the essential base of the food chain; and
• affect the amount of light that penetrates into the water column. Like most plants, algae
require light, a supply of inorganic nutrients, and specific temperature ranges to grow and
reproduce. Of these factors, it is usually the supply of nutrients that will dictate the amount
of algal growth in a lake. In most lakes, increasing the supply of nutrients (especially
phosphorus) in the water will usually result in a larger algal population.
Factors that Affect Algal Growth
There are a number of environmental factors that influence algal growth. The major factors
include:
• the amount of light that penetrates the water (determined by the intensity of sunlight, the
amount of suspended material, and water color);
• the availability of nutrients for algal uptake (determined both by source and removal
mechanisms);
• water temperature (regulated by climate, altitude, et cetera);
• the physical removal of algae by sinking or flushing through an outflow;
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• grazing on the algal population by microscopic animals, fish, and other organisms;
• parasitism by bacteria, fungi, and other microorganisms; and
• competition pressure from other aquatic plants for nutrients and sunlight.
It is a combination of these and other environmental factors that determines the type and quantity
of algae found in a lake. It is important to note, however, that these factors are always in a state of
flux. This is because a multitude of events, including the change of seasons, develop ment in the
watershed, and rainstorms constantly create "new environments" in a lake.
These environmental changes may or may not present optimal habitats for growth or even survival
for any particular species of algae. Consequently, there is usually a succession of different
species in a lake over the course of a year and from year to year.
The Overgrowth of Algae
Excessive growth of one or more species of algae is termed a bloom. Algal blooms, usually
occurring in response to an increased supply of nutrients, are often a disturbing symptom of
cultural eutrophication.
Blooms of algae can give the water an unpleasant taste or odor, reduce clarity, and color the lake
a vivid green, brown, yellow, or even red, depending on the species. Filamentous and colonial
algae are especially troublesome because they can mass together to form scums or mats on the
lake surface. These mats can drift and clog water intakes, foul beaches, and ruin many
recreational opportunities.
Citizen programs designed to monitor the algal condition of a lake usually require the volunteers
to measure:
• the water clarity;
• the density of the algal population; and
• the concentration of the critical algal nutrient, phosphorus.
2.C Aquatic Plants
Aquatic plants have true roots, stems, and leaves. They, too, are a vital part of the biological
community of a lake. Unfortunately, like algae, they can overpopulate and interfere with lake uses.
Aquatic plants can be grouped into four categories:
• Emergent plants are rooted and have stems or leaves that rise well above the water surface.
They grow in shallow water or on the immediate shoreline where water lies just below the
land surface. They are generally not found in lake water over two feet deep.
• Rooted floating-leaved plants have leaves that rest on, or slightly above, the water surface.
These plants, whose leaves are commonly called lily pads or "bonnets," have long stalks
that connect them to the lake bottom.
• Submergent plants grow with all or most of their leaves and stems below the water surface.
They may be rooted in the lake bottom or free-floating in the water. Most have long, thin,
flexible stems that are supported by the water. Most submergents flower above the surface.
• Free-floating plants are found on the lake surface. Their root systems hang freely from the
rest of the plant and are not connected to the lake bottom.
Through photosynthesis, aquatic plants convert inorganic material to organic matter and
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oxygenate the water. They provide food and cover for aquatic insects, crustaceans, snails, and
fish. Aquatic plants are also a food source for many animals. In addition, waterfowl, muskrats, and
other species use aquatic plants for homes and nests.
Aquatic plants are effective in breaking the force of waves and thus reduce shoreline erosion.
Emergents serve to trap sediments, silt, and organic matter flowing off the watershed. Nutrients
are also captured and utilized by aquatic plants, thus preventing them from reaching algae in the
open portion of a lake.
Factors that Affect Aquatic Plant Growth
There are many factors that affect aquatic plant growth including:
• the amount of light that penetrates into the water;
• the availability of nutrients in the water (for free-floating plants) and in the bottom sediments
(for rooted plants);
• water and air temperature;
• the depth, composition, and extent of the bottom sediment;
• wave action and/or currents; and
• competition pressure from other aquatic plants for nutrients, sunlight, and growing space.
The Overgrowth of Aquatic Plants
Excessive growth of aquatic plants is unsightly and can severely limit recreation. Submergents
and rooted floating-leaf plants hinder swimmers, tangle fishing lines, and wrap around boat
propellers. Fragments of these plants can break off and wash up on beaches and clog water
intakes.
For many species, fragmentation is also a form of reproduction. An overgrowth problem can
quickly spread throughout a lake if boat propellers, harvesting operations, or other mechanical
actions fragment the plants, allowing them to drift and settle in new areas of the lake.
Free-floating plants can collect in great numbers in bays and coves due to prevailing winds.
Emergent plants can also be troublesome if they ruin lake views and make access to open water
difficult. In addition, they create areas of quiet water where mosquitoes can reproduce.
Citizen monitoring programs designed to characterize the aquatic plant condition usually:
• map the distribution of plant beds in the lake;
• estimate the density of plants along a transect line in a selected area; and
• collect specimens for professional identification.
2.D Dissolved Oxygen
The amount of oxygen in the water is an important indicator of overall lake health. In fact, much
information can be learned about a lake by examining just this parameter.
Oxygen plays a crucial role in determining the type of organisms that live in a lake. Some species,
such as trout, need consistently high oxygen concentrations to survive. Other aquatic species are
more tolerant of low or fluctuating concentrations of oxygen.
Oxygen is supplied naturally to a lake by:
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• the diffusion of atmospheric oxygen into the water; and
• the production of oxygen through photosynthesis by aquatic plants and algae.
Oxygen is easily dissolved in water. In fact, it is so soluble that water can contain a greater
percentage of oxygen than the atmosphere. Because of this phenomenon, oxygen naturally
moves (diffuses) from the air into the water. Agitation of the water surface by winds and waves
enhances this diffusion process.
Vertical mixing of the water, aided by winds, distributes the oxygen within the lake. In this manner,
it becomes available to the lake's community of oxygen-breathing organisms.
Water temperature affects the capacity of water to retain dissolved oxygen. Cold water can hold
more oxygen than warm water. Therefore, a lake will typically have a higher concentration of
dissolved oxygen during the winter than the summer.
Factors that Determine Dissolved Oxygen Concentration
There are a number of factors that determine the amount of oxygen found in a lake including:
• climate;
• water temperature and thermal stratification of the water column;
• wind and waves that create movement on the surface and aid diffusion from the
atmosphere;
• the amount of algae and aquatic plants (oxygen is added to the water as a by-product of
photosynthesis);
• the amount of respiring life forms including algae, aquatic plants, fish, bacteria, fungi, and
protozoans (respiration removes oxygen from the water and produces carbon dioxide);
• the rate at which organic matter reaches the lake bottom and is decomposed by respiring
microorganisms (influenced by growth and death rates of life forms in the lake and the input
of organic material from incoming streams and surface runoff);
• the oxygen content of incoming ground water and surface streams; and
• the shape and depth of the lake basin.
Fluctuating Oxygen Concentrations
Oxygen is essential for aquatic life. Without oxygen, a lake would be an aquatic desert devoid of
fish, plants, and insects. For this reason, many experts consider dissolved oxygen to be the most
important parameter used to characterize lake water quality.
Algae and aquatic plants produce oxygen as a by-product of photosyn thesis but also take in
oxygen for respiration. Respiration occurs all the time, but photosynthesis occurs only in the
presence of light. Consequently, a lake that has a large population of algae or plants can
experience a great fluctuation in dissolved oxygen concentration during a 24-hour period.
During a sunny day, photosynthesis occurs and can supersaturate the water with oxygen. At
night, plants no longer produce oxygen; however, they continue to consume oxygen for
respiration. In some lakes after dark, dissolved oxygen can be depleted by the plants at a rate
faster than it can be diffused into the lake from the atmosphere. In extreme cases, the oxygen in
the water can become depleted. This lack of oxygen will cause fish and other aquatic organisms
to suffocate.
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Extreme fluctuations of dissolved oxygen concentrations place great stress on the
oxygen-breathing creatures in the lake. Only tolerant species can survive in this type of
environment. Unfortunately, tolerant species are usually the least desirable for recreational
purposes. Carp are an example of a tolerant fish. Trout, on the other hand, are highly intolerant of
fluctuating oxygen levels.
In addition to the impact on living organisms, the lack of oxygen in a lake also has profound
effects on water chemistry and eutrophication. To explain this situation, one must understand the
temperature cycle, how it affects water density, and the phenomena of lake overturn and thermal
stratification .
The Temperature Cycle
Most U.S. lakes with a depth of 20 feet or more stratify into two tempera ture-defined layers during
the summer season. The water in the upper layer (epilimnion) is warm, well lit, and circulates
easily in response to wind action. The deep layer (hypolimnion) is dark, cold, more dense, and
stagnant.
These two layers are separated by a transition zone ( metalimnion) where temperatures change
rapidly with depth. The metalimnion functions as a barrier between the epilimnion and the
hypolimnion.
The magnitude of the temperature difference between the two layers defines how resistant they
are to mixing. A large temperature difference means that the layers are stable and that it would
take a great deal of wind energy to break down the stratification and mix the layers.
In the fall, lowered air temperatures eventually cool the waters in the upper layer to a point where
they become the same temperature (and density) as the lower layer. At this time, the resistance to
mixing is removed and the entire lake freely circulates in response to wind action. This action is
known as fall overturn.
Layers again form during the winter. However, it is the upper zone that is slightly colder than the
deeper layer. In the spring, increasing air temperatures warm the upper layer to a point that it
becomes the same temperature as the bottom zone. Wind action then mixes the entire lake and
spring overturn occurs.
Oxygen Depletion in the Lower Layer
Bacteria, fungi, and other organisms living on the lake bottom break down organic matter that
originates from the watershed and the lake itself. Algae, aquatic plants, and animals all provide
food for these decomposers when they excrete, shed, and die. Like higher forms of life, most
decomposers need oxygen to live and perform their important function.
The mixing action of spring and fall overturn distributes oxygen through out the water column.
During summer stratification, however, the lower layer is cut off from the atmosphere. There is
also usually too little light to support photosynthesis by algae or aquatic plants. Therefore, with no
supply source, what oxygen there is in the lower layer can be progressively depleted by an active
population of decomposers.
When the dissolved oxygen concentration is severely reduced, the bottom organisms that depend
on oxygen either become dormant, move, or die. Fish and other swimming organisms cannot live
in the lower layer. As a result, trout and other game fish that require deep, cold water and high
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oxygen levels may be eliminated from the lake altogether.
Other Problems Caused by Lower Layer Oxygen Depletion
Oxygen depletion in the lower layer occurs "from the lake bottom up." This is because most
decomposers live in or on the lake sediments. Through respiration, they will steadily consume
oxygen. When oxygen is reduced to less than one part per million on the lake bottom, several
chemical reactions occur within the sediments. Notably, the essential plant nutrient, phosphorus,
is released from its association with sediment-bound iron and moves freely into the overlying
waters.
If wind energy breaks down a lake's stratification, this phosphorus may be transported into the
upper layer where it can be used by algae and aquatic plants. This internal pulse of phosphorus
(often termed internal loading) can thus accelerate algal and aquatic plant problems associated
with cultural eutrophication.
Iron and manganese are also released from the sediments during anoxic (no oxygen) periods.
These elements can cause taste and odor problems for those who draw water from the lower
layer for drinking or domestic purposes.
Fortunately, many of the negative effects of anoxic conditions are eliminated during overturn. As
the waters of the lake are mixed and re-oxygenated, many of the constituents released from the
sediments chemically change and precipitate back on to the lake bottom. Others are reduced in
concentration by their dilution into the waters of the entire lake.
Overturns do also bring nutrients back up to the surface where they become available to the
algae. Therefore, it is not unusual to see algal blooms associated with overturns.
Citizen monitoring programs designed to characterize the dissolved oxygen condition in lakes
have volunteers:
• measure dissolved oxygen from the surface to bottom; and
• measure water temperature from the surface to bottom.
These temperature and dissolved oxygen profiles help define the thermal layers and identify any
oxygen deficit within the water column.
2.E Other Lake Conditions
Sediment Deposition
The gradual filling-in of a lake is a natural consequence of eutrophication. Streams, stormwater
runoff, and other forms of moving water carry sand, silt, clays, organic matter, and other
chemicals into the lake from the surrounding watershed. These materials settle out once they
reach quieter waters. The rate of settling is dependent on the size of the particles, water velocity,
density, and temperature.
The sediment input to a lake can be greatly accelerated by human develop ment in the
watershed. In general, the amount of material deposited in the lake is directly related to the use of
watershed land. Activities that clear the land and expose soil to winds and rain (e.g., agriculture,
logging, and site development) greatly increase the potential for erosion. These activities can
significantly contribute to the sediment pollution of a lake unless erosion and runoff is carefully
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managed.
Sediment material from the watershed tends to fertilize aquatic plants and algae because
phosphorus, nitrogen, and other essential nutrients are attached to incoming particles. If a large
portion of the material is organic, dissolved oxygen can decrease as a result of respiration of
decomposers breaking down the organic matter.
Sedimentation also can ruin the lake bottom for aquatic insects, crustaceans, mussels, and other
bottom-dwelling creatures. Most important, fish spawning beds are almost always negatively
affected.
The input of sediments to a lake makes the basin more shallow, with a corresponding loss of
water volume. Thus, sedimentation affects navigation and recreational use and also creates more
fertile growing space for plants because of increased nutrients and exposure to sunlight.
Citizen volunteer programs that focus on sedimentation generally measure sediment buildup over
time at a few select sites (e.g., near the mouth of a stream).
Sediment Turbidity
Not all sediment particles quickly settle to the lake bottom. The lighter, siltier particles often stay
suspended in the water column or settle so lightly on the bottom that they can be easily stirred up
and resuspended with even slight water motion. This causes the water to be turbid and brownish
in appearance. Sediment blocks light from penetrating into the water column. It also interferes
with the gills offish and the breathing mechanism of other creatures.
Volunteer programs that focus on sediment turbidity will usually monitor water clarity and the
amount of suspended solids in the water.
Lake Acidification
Acidity is a measure of the concentration of hydrogen ions on a pH scale of 0 to 14. The lower the
pH, the higher the concentration of hydrogen ions. Substances with a pH of 7 are neutral. A
reading less than 7 means the substance is acidic. If the pH is greater than 7, it is basic (alkaline).
Because the pH scale is logarithmic, each whole number increase or decrease on the 0 to 14
scale represents a 10-fold change in acidity.
Acidic lakes occur in areas where the watershed soils have little natural buffering capacity. Acidic
deposition (commonly called acid rain) and other artificial or natural processes can further
contribute to lake acidity. Most aquatic plants and animals are sensitive to changes in pH. Thus,
acidic lakes tend to be clear because they contain little or no algae. Fish are also thought to be
negatively affected by lowered pH. In fact, many acidic lakes have no fish populations.
Acid rain occurs in areas where the combustion of fossil fuels increases the concentration of
sulfuric and nitric acids in the atmosphere. These acids can be transported thousands of miles
and eventually deposited back to earth in rain or snow.
Acidity may also enter lakes from drainage that passes through naturally acidic organic soils.
These soils may become more acid through land use practices such as logging and mining.
Acidic drainage from abandoned mines affects thousands of miles of streams and numerous
lakes throughout Appalachia. Acid mine drainage also occurs in the Midwest coalfields of Illinois,
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Indiana, and Ohio, and in coal and metal mining areas of the western United States.
Volunteer programs that focus on acidification generally sample for pH and alkalinity. These are
two measurements that provide an indication of the acid/base status and the buffering capacity of
the water, respectively.
Bacteriological Conditions at Beaches
The sanitary quality of bathing beaches is a special concern to swimmers. There are a wide
variety of disease-causing bacteria, viruses, parasites, and other microorganisms that can enter
the water and be trans mitted to humans. Some are indigenous to natural waters. Others are
carried from wastewater sources including septic systems and runoff from animal and wildfowl
areas. Infected swimmers themselves are also a source of pathogens.
The ideal way to determine potential health hazards at natural bathing beaches is to test directly
for disease-causing organisms. Unfortunately, the detection of these organisms requires very
complex procedures and equipment. In addition, there are hundreds of different kinds of
pathogens; to test for each one would be impractical. Most public health officials, therefore,
simply test for the presence of an indicator organism. The relative abundance of the indicator
organism in a sample can serve as a warning of the likely presence of other, more dangerous
pathogens in the water.
Citizen volunteer programs that focus on bacterial quality at bathing beaches as the lake condition
to be monitored generally sample for one or more indicator organisms throughout the swimming
season.
The indicator organisms most often chosen for monitoring are fecal coliform bacteria or
enterococci bacteria. The latter group of bacteria is more disease-specific and may be most
appropriate for routine sample analy sis. Usually, health departments recommend weekly
sampling for bathing areas.
Swimmer's Itch
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In some regions, schistosome cercarial dermatitis or
swimmer's itch is a problem condition. Swimmer's itch is
caused by a parasitic flatworm that lives in the
bloodstream of a host aquatic bird species. The eggs of
the flatworm are passed into the lake in the excrement of
the bird.
Once in the water, the eggs will hatch and the larvae
searches for and penetrates into a certain species of
snail. The larvae grows in the snail and eventually
emerges as a second larval stage known as a cercaria.
The cercaria normally penetrates the skin of the host
species of
bird and the life cycle begins again. The cercaria can
also, by
mistake, penetrate the skin of swimmers. Since humans
are not the
host needed for growth, the larvae soon dies. Although
harmless,
the cercaria can leave the swimmer with an itchy welt for
a few days.
Because of the prevelance of swimmer's itch in some
regions, another
potential candidate for citizen monitoring can be the
presence of
cercaria in bathing beach waters.
References:
New York State Dept. of Environmental Conservation and Federation of Lake Associations, Inc.
1990. Diet fora Small Lake: A New Yorker's Guide to Lake Management. Albany.
Olem, H. and G. Flock, eds. August, 1990. The Lake and Reservoir Restoration Guidance Manual.
2nd ed. EPA 440/4-90-006. Prep. N. Am. Lake Manage. Soc. for U.S. Environ. Prot. Agency, Off.
Water, Washington, DC.
Standard Methods for the Examination of Water and Wastewater. 16th ed. 1985. Am. Pub. Health
Ass., Am. Waterworks Ass., and Water Pollu. Control Fed. 1985. American Public Health
Association. Washington, DC.
U.S. Environmental Protection Agency. April, 1990. Rhode Island Sea Grant College Program.
National Directory of Citizen Volunteer Environmental Monitoring Programs. EPA 440/9-90-004.
Off. Water, Washington, DC.
U.S. Environmental Protection Agency. August 1990. Volunteer Water Monitoring: A Guide for
State Managers . EPA 440/4-90-010. Off. Water, Washington, DC.
Return to the Table of Contents
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Office of Water
Volunteer Lake Monitoring: A Methods Manual
Chapter 3: Monitoring Algae
3.A Algal Condition Parameters
Monitoring the algal condition in lakes is the focus of the majority of citizen volunteer monitoring
programs operating today. There are three prominent reasons for this decision.
• Most citizen volunteers desire lakes that have clear water with a slight blue tinge. Deviation
from this accepted standard raises public interest about water quality. In many lakes, it is
the algae population that decreases clarity and colors the water.
• Parameters commonly used to measure the algal condition of a lake can be sampled easily
by volunteers using basic equip ment.
• Parameters that measure the algal condition form the basis for many commonly used
trophic state indices. These indices provide a quantitative means of describing the level of
lake aging (eutrophi cation). Using a trophic state index, program officials can rank lakes
according to the results of the monitoring program.
Three parameters are most often used by citizen monitoring programs to measure algal conditions
in lakes.
• Secchi disk transparency
This parameter is a measurement of water clarity. In many lakes, a reduction of clarity
occurs as the algal population grows. In these cases, a Secchi disk reading can be used an
idirect measure of algal density.
• Chlorophyll a
This parameter is a more reliable indicator of algal quantity because chlorophyll a is a
chemical extracted directly from the algal cells present in a water sample.
• Total phosphorus
This parameter is an essential plant nutrient that stimulates the growth of algae in many
lakes (the more phosphorus in the lake, the more algae). By measuring phosphorus
concentration, monitors can get an indication of water fertility.
Each of the three parameters, if measured by itself, will not provide a complete picture of the algal
condition of a lake. Measured together, how ever, they can provide valuable information about the
relationship between water fertility and algal growth. Volunteers are especially interested in how
algal growth affects water clarity, the lake trait most noticed by the majority of lake residents and
users.
Secchi Disk Transparency
First developed by Professor P.A. Secchi in 1865 for a Vatican-financed Mediterranean
oceanographic expedition, the Secchi disk has since become a standard piece of equipment for
lake scientists. It is simply a weighted circular disk 20 centimeters (about eight inches) in diameter
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with four alternating black and white sections painted on the surface.
The disk is attached to a measured line that is marked off either in meters (subdivided by tenths of
meter), if using metric units, or feet (subdivided by tenths of feet or inches), if using English units.
The Secchi disk is used to measure how deep a person can see into the water. It is lowered into
the lake by the measured line until the observer loses sight of it. The disk is then raised until it
reappears. The depth of the water where the disk vanishes and reappears is the Secchi disk
reading.
In extremely clear lakes, disk readings greater than 10 meters can be measured. On the other
hand, lakes affected by large amounts of algal growth, suspended sediments, or other conditions
often have readings of less than one-half meter.
In some shallow lakes, it is impossible to get a Secchi disk reading because the disk hits the
bottom before vanishing from sight. This means the true Secchi disk reading is greater than the
depth of the lake in that particular location.
Citizen volunteers in the United States are most comfortable
with
English units of measurement. Scientists, however, usually
report lake measurements in metric units.
In general, citizen monitoring programs should use metric
units
when reporting results, especially if a program goal is to
provide
information to government agencies. Even if the data will be
used
for educational purposes, incorporating metric units into the
sampling protocol will introduce the volunteers and the public
to
the scientific way of monitoring lakes.
Unfortunately, Secchi disk data are among the most abused and misinterpreted measurements in
monitoring programs because people often directly equate Secchi disk readings with algal
density. There are, how ever, many other factors found both inside and outside the lake that affect
how deep a person can see into the water.
Inside the lake, water transparency can be reduced by:
• microscopic organisms other than algae;
• natural or unnatural dissolved materials that color or stain the water; and
• suspended sediments.
Factors outside the lake can also affect a Secchi disk reading. These outside factors can include:
• the observer's eyesight and other sources of human error;
• the angle of the sun (time of day, latitude, season of the year);
• weather conditions (cloud cover, rain); and
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• water surface conditions (waves, sun glare, surface scum).
In sum, the Secchi disk should always be considered simply as an instrument to measure water
transparency. Algae can play an important role in reducing transparency; however, this
assumption must be proven by measuring a parameter directly associated with the algal
population. For many citizen monitoring programs, this parameter is chlorophyll a.
Chlorophyll a
Chlorophyll a is the green photosynthetic pigment found in the cells of all algae. By taking a
measured sample of lake water and extracting the chlorophyll a from the algae cells contained in
that sample, monitors can get a good indication of the density of the algal population.
The chlorophyll a concentration cannot be considered a precise mea surement of algal density,
however, because the amount of chlorophyll a found in living cells varies among algal species.
Thus, two lakes can have identical densities of algae yet have significantly different concentra
tions of chlorophyll a because they are dominated by different species.
Direct comparability, even within a single lake, is further complicated by the fact that the amount
of chlorophyll a in an algal cell varies with light conditions. Healthy algal cells constantly try to
maintain chlorophyll concentrations at a level for maximum photosynthetic efficiency. Chlorophyll
in a cell usually decreases during high light conditions and increases during the night or low light
conditions.
Similarly, a cell that is sinking down into the water column (away from the sun) may also produce
more chlorophyll to compensate for the lower light levels found at greater depths. Changing
seasons also create higher or lower light conditions according to the position of the sun which, in
turn, affects chlorophyll production.
Despite these drawbacks, the ease of sampling and relatively low cost of analysis makes
chlorophyll a an attractive parameter for characterizing the algal density in lakes, especially for
volunteer monitoring programs.
Chlorophyll a is analyzed in a laboratory from a sample collected by a volunteer. The simplest
protocol is to ship the water sample to the labora tory for analysis.
Alternatively, some citizen monitoring programs have volunteers pass a measured volume of lake
water through a filtering apparatus containing a prepared filter paper disk. The filter paper lets the
water pass through but retains the algae cells on its surface. The volunteer then removes the disk
and places it in a special tube to be forwarded to the laboratory for chlorophyll a analysis.
In some instances, this procedure may produce lower than actual results for chlorophyll a
concentrations if the filtering procedure is not followed exactly. QA/QC considerations will
determine if this method is a feasible alternative for a volunteer program.
Total Phosphorus
Phosphorus is one of several essential nutrients that algae need to grow and reproduce. In many
lakes, phosphorus is in short supply. Therefore, it often serves as a limiting factor for algal growth.
Phosphorus migrates to lake water from only a few natural sources. As a result, lakes located in
pristine wilderness settings rarely have problems with algal blooms. Humans, on the other hand,
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use and dispose of phosphorus on a daily basis. Phosphorus is found in such common items as
fertilizers, foods, and laundry detergents.
Lakes with developed watersheds often receive a portion of this human-generated phosphorus
through runoff, septic leachate, and other sources. This phosphorus fertilizes the water and can
stimulate increased algal growth.
Algae most readily consume a form of phosphorus known as orthophosphate, the simplest form of
phosphorus found in natural waters. In fact, orthophosphate is so quickly taken up by a growing
algal population that it often is found only in low concentrations in lakes.
Phosphorus is found in lakes in several forms other than orthophosphate. For example, when
phosphorus is absorbed by algae, it becomes organically bound to a living cell. When the cell
dies, the phosphorus is still bound to particles even as it settles to the lake bottom. Once the
decomposer organisms break down the cell, the phosphorus can become attached to calcium,
iron, aluminum, and other ions.
Under anoxic conditions, chemical reactions can release phosphorus from the sediments to the
overlying waters. Spring or fall overturn may then redistribute it back to the surface where it can
be taken up by another algal cell.
Phosphorus, therefore, is in a constant state of flux as environmental conditions change and
plants and animals live, die, and decompose in the lake. Because the forms of phosphorus are
constantly changing and recycling, it is generally most appropriate for citizen monitoring programs
to measure all forms of phosphorus together. This one "umbrella" measurement is known as total
phosphorus.
This manual describes a method that instructs the volunteer to collect a water sample, transfer it
into a sample bottle that contains an acid preservative, and then ship it to a laboratory for total
phosphorus analysis.
Alternatively, there are test kits on the market for total phosphorus analysis. To conduct the test,
however, volunteers must be well-trained and possess special laboratory equipment. For these
reasons, phosphorus test kits are not generally appropriate for volunteer monitoring programs.
In some instances, orthophosphate may be a parameter of interest since it is the form of
phosphorus available for uptake by algae. Like total phosphorus, orthophosphate is best
measured in a laboratory.
3.B Where to Sample
Analyzed together, the three parameters Secchi disc, chlorophyll a, and total phosphorus can
provide information on the quantity of free-floating algae, the critical nutrient that feeds the
population, and how the algae affect water transparency. Where the parameters are sampled on
the water surface and in the water column is an important consideration when planning a program
to monitor algal conditions.
A lake and its water quality are not uniform from shore to shore or from surface to bottom. Lake
morphometry, exposure to winds, incoming streams, watershed development, and human activity
can greatly influence the algal conditions found at any one location in the lake.
Thus, the planning committee or supervising staff is challenged to select sample locations that
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will best characterize the algal condition in accordance with the goals and objectives of the
monitoring program. Increasing the number of sampling sites will reduce uncertainty, but it will
come at increased cost.
Where to Sample on the Water Surface
The majority of citizen monitoring programs are designed to measure average algal conditions in
the lake's pelagic (deep, open water) zone. For these programs, the number and location of
sampling sites are most influenced by the size and shape of the lake basin.
In most cases, a site over the deepest section of the lake best represents average conditions. In
natural lakes that are circular in shape, the deepest section is usually near the middle. In
reservoirs, the deepest section is usually near the dam.
Many lakes, however, possess significant arms or bays. In this instance, it is often useful to
sample the deepest section in each individual arm or bay. In many cases, monitors will find a
significant difference between sites, especially if one arm of the lake is more populated.
Some monitoring programs, on the other hand, are designed to characterize the algal condition at
its worst location. For these types of programs, certain known problem areas may be targeted for
sampling. For example, a particular bay may be monitored because it "collects" algae and other
materials because of prevailing winds.
More often, however, "worst area" sampling is designed to monitor how point or nonpoint sources
of nutrient pollution affect water quality and algal growth. Examples of potential sources of
nutrient pollution include farms, residential developments, and sewage outfalls. This monitoring
can provide evidence that specific watershed management efforts are needed to manage the algal
population.
The number and location of sampling sites can also be influenced by the basic goal of the
program. A program managed primarily for public education, for example, may wish to include
stations for various non -scientific reasons such as their proximity to residential neighborhoods or
convenience of access. Such a program may even include additional stations in a lake so more
volunteers can participate in monitoring.
Sample site selection should be consistent within a program in order to get results worthy of
lake-to-lake comparison. For example, if the deepest part of the lake is chosen as the location for
sampling, all the lakes in the program should then be sampled at the deepest site.
To select the location of a sampling site, the manager must possess some preliminary information
about the lake including:
• a bathymetric (depth contour) map (or general knowledge of the location of maximum depth
so that soundings can be taken in the field and a suitable sampling location identified);
• a watershed map with the lake's major inflows and outflows;
• a historical summary of water quality including the location of previous sampling sites and
documentation of any lake problems (algal blooms, weed growth, fish kills);
• updates of any current activities in the watershed that may affect sampling results (point
sources such as sewage plant or storm drain outfalls and nonpoint sources such as
agricultural, urban, logging, and construction areas); and
• updates of any current lake activities that may affect sampling results, including dredging,
water level drawdowns, and chemical applications.
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All this information will influence the selection of the sampling site. It is also important for
interpreting the results of data collection efforts.
In the field, the program manager and the volunteer should work together to identify and locate
the proper sampling site location. Once identified, the site should be clearly marked on a lake
map. The task of locating the site can be practiced by the volunteer under the supervision of the
program manager.
For shoreline or near-shore stations, finding the site will probably not be a problem. Many
programs, however, will require volunteers to sample over the deepest portion of the lake. This
usually means the monitoring site will be somewhere in the middle of the waterbody. For
volunteers to return consistently to the same sampling site location, they must use a method.
Two simple ways to find the site are by:
• locating the site by using landmarks visible on the shore; or
• setting a permanent marker buoy at the sampling location.
Shoreline Landmark Method
On land, volunteers know where they are located by finding familiar landmarks. The same
process can be used on water, except that the landmarks are located on the shoreline. On an
initial training trip, the volunteer and the program manager must designate an "official" site
location.
Once securely anchored at the site, the volunteer should pick out two permanent landmarks on
shore (a dwelling, tall tree, large rocks) that align one behind the other. This alignment forms an
imaginary bearing line through the objects to the site.
Then, at about a 90 degree angle, two more aligning landmarks should be identified. These
landmarks then form a second bearing line to the sampling site. Volunteers should mark these
landmarks and bearing lines on their lake map for future reference. They should also practice
finding the site location with the program manager.
To further verify that volunteers have found the proper sampling site, the program manager may
also require that they perform a depth check using the anchor rope, a weighted calibrated
sounding line, or an electric "fish-finder" apparatus that indicates bottom depth.
Marker Buoy Method
If the lake is small and protected from strong winds and waves, a marker buoy may be the
simplest way to designate a sample site location. In many public lakes, however, it is illegal to set
out buoys without proper permits. The rules and regulations regarding buoys should be checked
before any placement.
There is a risk that a marker buoy will be moved by winds, waves, and /or lake users. Thus,
volunteers should also be trained to verify that the buoy is in the proper location using the
shoreline landmark method before starting the sampling procedure. This training will be useful if
the buoy is lost or needs to be repositioned.
3.C Where to Sample in the Water Column
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Free-floating algae grow and reproduce in the photic zone. This zone constitutes the upper
portion of the water column where sunlight penetrates and stimulates photosynthesis in the algal
cells. In programs designed to measure the algal condition of a lake, water samples are taken
from the photic zone and analyzed in a laboratory for their chlorophyll a and total phosphorus
content.
Where these samples are taken in the photic zone is another important decision that must be
made by the planning committee. There are two basic choices for water sampling in the photic
zone. Volunteers can collect:
• a point sample taken at a specific depth; or
• an integrated sample from a range of depths.
Point Sampling
Point sampling refers to the collection of a water sample from a specific depth in the water
column. Also known as grab sampling, it is the method most often used in monitoring programs.
When measuring the algal condition parameters, a sample is usually taken at a selected depth
between one-half and two meters. (Water samples are generally not collected directly at the
surface because floating substances such as pollen and gasoline residue will contaminate them.)
If a depth of one-half meter is selected, volunteers can collect the sample by simply submerging
the sample bottle to about elbow depth. For deeper point sampling, some type of water sampler
instrument must be used.
A Kemmerer or Van Dorn water sampler is commonly used to collect water at a specific depth.
These devices are cylindrical tubes with stoppers at each end. After the sampler has been
lowered to the desired depth (marked on the lowering line), the volunteer slides a weight (called a
messenger) down the line.
When the messenger reaches the sampler, it hits a trigger mechanism and the two stoppers snap
shut, trapping the sample of water from that depth. The sampler is then hauled back into the boat
and the sample water poured into a container.
The goals of the monitoring program and how the water quality data will be used will help the
planning committee determine where a point sample should be collected. A depth of one meter is
selected many times as a representative depth of photic zone conditions for chlorophyll a and
total phosphorus analyses.
If a water sampler is used, other depths in the water column also can be easily sampled by the
volunteer. Total phosphorus is an especially interesting parameter to monitor at different points in
the water column, in addition to the upper layer photic zone.
As discussed in Chapter 2, phosphorus is released from bottom sediments under anaerobic
conditions. If the lake is strongly stratified in the summer, and wind energy does not mix the water
column, the bottom-released phosphorus cannot reach the photic zone and stimulate increased
algal growth. In some lakes, however, summer stratification occasionally breaks down and the
bottom phosphorus does reach the surface waters, causing sudden algal blooms.
This internal loading of phosphorus is often important when analyzing the algal condition of
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productive lakes. For this reason, the planning commit tee should consider having volunteers
collect point samples from the bottom and middle of the water column for total phosphorus
analysis, as well as in the photic zone.
Integrated Sampling
An integrated sample combines water from a range of depths in the water column. It is essentially
a mixture of point samples designed to represent more of the photic zone than a single sample.
The simplest way for volunteers to collect an integrated sample is to use a hose and bucket.
Basically, a measured length of hose is weighted on one end and then lowered into the lake.
While the hose descends, it collects a vertical column of water. By plugging the surface end and
then bringing the lowered end to the surface with a line, an intact column of water can then be
emptied into a bucket and a sample drawn for laboratory analysis.
A basic drawback is that this method can not be easily standardized. Each volunteer will develop
his/her own variation of this sample collection technique. Losing a portion of the sample while
bringing up the hose may also be a problem for some volunteers. For these reasons, many
monitoring programs rely on point sampling for measuring the algal conditions of lakes.
3.D Frequency of Sampling
There is usually a change in the quantity and species of algae occur ring in a lake throughout the
year. Often algal density increases in the spring and early summer as water temperatures
increase and nutrients become available in the well-lit upper layer as a result of spring overturn.
When summer arrives and the lake stratifies, the algae population may change as the supply of
orthophosphate in the upper layer becomes depleted and/or microscopic animals (zooplankton)
graze on the population. After the summer, fall overturn can once again bring fresh nutrients to
the well-lit upper zone and stimulate increased algal growth.
A variety of other factors can also affect algal habitat and growth response, especially during the
summer growing season. Storms can churn the lake and cause a temporary upwelling of
nutrients from the lake bottom. Phosphorus-rich runoff can escape from residential or agricultural
areas after rainstorms, drain into the lake, and stimulate growth. On the other hand, chemicals or
herbicides that are toxic to algae may be released to the water and cause a (planned or
unplanned) population crash.
The planning committee should base its decision on how often to sample on data quality criteria,
costs, and other practical considerations.
Many citizen monitoring programs have found it appropriate to sample algal conditions on a
two-week or bi-monthly cycle. In most cases, this time period has proven adequate to monitor
changes in the algal parameters and, at the same time, fit into volunteers' participation schedules.
However, if conditions are known to change at more frequent intervals (if lake water flushes
quickly through an inlet and outlet), the committee may determine that weekly sampling is more
appropriate.
More frequent sampling also improves the odds of measuring a short-term event such as an algal
bloom or a sudden pulse of phospho rus input because of storm runoff or a sewage plant bypass.
Expense becomes a key factor when determining sampling frequency because each sampling
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round will increase program costs.
3.E Length of the Sampling Season
An ideal monitoring program runs year-round to collect the full amount of seasonal data on the
lake. This regime would test the dedication of citizen volunteers to an extreme, however. A more
practical sampling period for citizen monitoring is from spring overturn to the end of the summer
growing season.
Spring overturn is important because it is when wind action circulates the entire volume of water.
Importantly, citizens can sample the spring algal blooms that are sometimes observed as a result
of increased nutrient availability and warming water temperatures.
The summer growing season corresponds with the main recreational season. It is during this time
that increased algal growth is most objectionable because it can interfere with swimming,
water-skiing, fishing, and other activities.
Fall overturn is another time when the water circulates and algal blooms typically occur. This
season is not as important to the general public, however, because it comes at the end of the
recreational season. Thus, fall algal blooms are not usually perceived as a problem. Volunteer
interest also wanes as the weather turns cooler and more unpredictable. For these rea sons, it is
often prudent to stop monitoring at the end of summer.
Section 3.F How to Sample
Presented in this section are suggested procedures for sampling Secchi disk depth, chlorophyll a,
and total phosphorus concentration for a citizen monitoring program. Basically, these sampling
activities are divided into four main segments.
• Confirming the sampling date and weather conditions and going through boating safety and
sampling equipment checklists prior to launching the sampling boat (Tasks 1 through 3).
• Finding the sampling site and documenting observations about the water and weather
conditions (Tasks 4 and 5).
• Taking a Secchi disk measurement and collecting water samples for chlorophyll a and total
phosphorus analysis (Tasks 6 and 7).
• Returning to shore and preparing the chlorophyll a and total phosphorus samples for
shipment to a laboratory (Tasks 8 and 9).
The program manager should provide volunteers with a sampling schedule and a sampling
protocol sheet. In general, monitors should be instructed to conduct sampling between 10 a.m.
and 3 p.m. Volunteers must understand, however, that there is flexibility in both the day and time,
especially in consideration of weather conditions.
Volunteers' common sense and good judgment dictate when it is appropriate to sample. Both
good and unacceptable weather conditions should be defined for volunteers during training
sessions. Under no circumstances should volunteers be on the water during rain or electrical
storms, high winds (white caps), or other unsafe conditions.
TASK1
Confirm sampling day and weather conditions. Elements of Task 1
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• Check the sampling date on the program sampling schedule.
• Check the current and forecasted weather and decide if the conditions allow for safe
sampling. The volunteer should also be instructed to confirm this decision after personally
inspecting lake conditions prior to launching the boat and beginning the sampling trip.
TASK 2
Go through the boating safety equipment checklist.
Before leaving shore, volunteers must confirm that all needed safety equipment is on board.
Boating safety is a subject that volunteers need to take seriously because they will be moving
around the boat, leaning over the edge, and working with equipment.
Volunteers should wear a life preserver (Type 1, 2 or 3 personal flotation device) at all times.
Volunteers should educate themselves about safe boating laws and the rules of the road.
Elements of Task 2
• Confirm that the following boating safety equipment is on board the sampling boat.
• Personal flotation device for each person. Devices must be Coast Guard-approved, readily
available, and the proper size
• First aid kit
• Other equipment that may be required by State and local boating laws. For example, boats
may be required to carry fire extinguishers and sound-producing devices. Also, the boat
must be registered according to State and local laws.
TASKS
Go through sampling equipment and supply checklist.
Before leaving shore, volunteers must make sure that they have all the needed sampling
equipment and supplies on board the boat. They must also confirm that other items are left on
shore.
Elements of Task 3
• Confirm that the following sampling equipment and supplies are on board the sampling
boat.
• Anchor (with a measured line if a depth check is required). Two anchors are helpful on
windy days, one off the bow and the other off the stern.
• Secchi disk with a measured line and a clothespin
• Water sampler instrument (for integrated or point sampling)
• Water sample collection container
• Ice cooler (with a closable lid) with frozen ice packs
• Clipboard and pencils
• Map of lake with sampling site and landmarks marked
• Sampling protocol sheet
• Sampling form
Confirm that the following supplies are on shore.
• Phosphorus sample shipping bottle (with a small amount of acid to preserve the sample)
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• New pair of vinyl gloves
• Chlorophyll a sample shipping bottle
• Shipping box with frozen ice packs
TASK 4
Position boat at the designated sample site.
Volunteers must locate the sample site on the water. Whether or not a marking buoy is used, the
position should be verified using the shoreline landmark method.
Once the site is located, volunteers can anchor the boat. Repositioning the anchor once it is
dropped should be discouraged, especially in shallow lakes, because it can stir up sediments
from the lake bottom. Increasing sediment turbidity may alter data results. After anchoring,
volunteers should allow the boat to stabilize. Then a depth check can be done.
TASKS
Complete the observations portion of the sampling form.
Volunteers should record their observations about the lake and weather conditions on the
sampling form. In addition, they should write down any unusual conditions that may affect the
sampling results. A suggested format for a data form is presented on page 45.
Reporting visual conditions such as water color and appearance will aid in interpreting data
results. For example, if the sampling trip was conducted after a storm, the water may temporarily
be more be more brownish and turbed than usual.
This turbidity probably will lower the Secchi disk reading and elevate the total phosphorus
concentration. Without the information concerning the rainstorm, an analyst might conclude that
other factors could have caused a decrease in water quality.
Elements of Task 5
• Record the name of the lake and site, the date, the time of sampling, and the names of
volunteers doing the sampling.
• Record water condition observations at the site including water color, suspended sediment
and algae, aquatic plants, waterfowl activity, and odor.
• Record weather conditions on the form including the amount of cloud cover (when taking
the Secchi disk reading), the approxi mate air temperature, the wind speed and direction,
and water surface conditions. Indicate any unusual weather conditions that may have
occurred in the past week including storms, high winds, and temperature extremes.
• Record any other factors or conditions that make the sam pling trip unusual or that may
potentially influence sample results. For example, report any chemical, mechanical, or
biologi cal control of algae or aquatic weeds that may have been done recently on the lake.
TASK 6
Measure the Secchi disk depth.
The Secchi disk is used to measure the depth that a person can see into the water
(transparency). A Secchi disk reading is a personal measure ment; it involves only two pieces of
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equipment, the disc and the person's eyesight.
Because it so individualistic, the Secchi disc measurement may have low comparability between
lakes and even between volunteers on the same lake. The key for consistent results is to train
volunteers to follow standard sampling procedures for every measurement. It is preferable to have
the same individual take the reading at a site throughout the entire sampling season.
The line attached to the Secchi disk must be marked according to the units and increments
designated by the planning committee. Many programs use meters as the measurement unit and
require volunteers to measure to the nearest one-tenth meter.
The line markings must be made using waterproof ink. Meter intervals on the line can be tagged
with a piece of duct tape with the interval measurement indicated on the tag.
Elements of Task 6
• Check to make sure that the Secchi disk is securely attached to the measured line.
• Lean over the side of the boat and lower the Secchi disk into the water, keeping your back
toward the sun to block glare.
• Continue to lower the disk until it just disappears from view. Lower the disk another one
third of a meter and then slowly raise the disc until it just reappears. Continue to move the
disk up and down until the exact vanishing/reappearing point is found.
• Attach a clothespin to the line at the point where the line enters the water. This is the point
the measurement will be read.
• Slowly pull the disk out of the water and record the measure ment based on the location of
the clothespin on the line.
This procedure can be repeated as a quality control check; an average of the two readings should
be recorded on the sampling form.
TASK 7
Collect a point sample for chlorophyll a and total phosphorus.
Described below are two point sampling procedures. Procedure A describes how to hand-collect a
sample approximately one-half meter below the surface. Procedure B describes how to collect a
sample at a select depth using a sampler such as a Kemmerer Bottle.
Procedure A. Elements of hand sampling just below the surface
• Remove the cap from the sampling container, taking care not to touch the container mouth.
• Rinse the container with lake water by holding it by the bottom and plunging it mouth-first
into the lake to about elbow depth. Your hand should always move in a forward motion so
that water will not slide over it into the bottle. Fill the container, turn the mouth upwards,
bring it above the surface, and empty the container.
• Rinse the cap at the same depth, holding the outside of the cap when plunging.
• Using the same motion, collect the sample of water in the con tainer. Tip out some of the
water to leave some air space and cap the container.
• Store the container in the cooler.
Procedure B. Elements of point sampling using a water sampler
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• Check to make sure that the water sampler is securely attached to the measured line
(marked in meters like the Secchi disk line).
• Lower the sampler gently into the water to the desired depth marked on the line (rough
treatment can trigger the closing mechanism prematurely).
• Slide the messenger down the line to close the stoppers.
• Gently haul the sampler to the surface, then release some of sample water into the
container. Swirl it in the container to rinse and then pour it out. Rinse the cap in the same
manner.
• Release sample water into the container until it is almost full, leaving some air space at the
top. Cap the container.
• Store the container in the ice cooler away from the light.
TASKS
Transferring sample water into shipping bottles.
Volunteers must bring the boat back to shore and unload the sampling equipment and supplies.
Next, they must move indoors or find an outdoor location that is dry and shielded from the wind.
Volunteers then transfer the water from the sample container into the two bottles that will be
shipped to the laboratory for analysis of chlorophyll a and total phosphorus concentrations.
During the training session, volunteers should be made aware how easy it is to contaminate the
phosphorus sample unless precautions are taken. Volunteers should be instructed to leave the
cap on the phosphorus shipping bottle until they are ready to pour the sample water into it.
Volunteers should wear clean vinyl gloves and should not smoke. They must always be aware
that the phosphorus sample bottle contains an acid that preserves the sample during transport to
the laboratory. This acid must be treated cautiously because it can burn skin or clothing if spilled
or mishandled. Volunteers should also not breathe the vapors from the opened bottle.
Because of the potential for spills or mishaps, the planning committee should prepare an
information sheet about the preservative acid. The sheet should include warnings and emergency
care instructions should the acid accidentally come in contact with volunteers' skin or clothes.
Volunteers should be told to keep the sheet nearby when working with this bottle.
Elements of Task 8
A. Phosphorus Sample Bottle
• Make sure the phosphorus sample bottle is labeled with:
• the parameter to be analyzed (total phosphorus).
• the date and the sample lake, location, and depth.
• any additional information such as an accession number for laboratory identification and the
acid content.
• Put on a new pair of vinyl gloves.
• Confirm that there is acid present in the bottom of the bottle by visual inspection.
• Move the total phosphorus sample bottle into position and remove the cap, being careful not
to spill the acid contents or breathe in the vapors.
• Gently shake the container with the sample water to re-suspend any settled material.
• Gently pour the sample water into the phosphorus bottle until the liquid reaches the fill line.
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• Cap the sample bottle and place it into the shipment container with the frozen ice packs and
close the lid so sunlight cannot reach it.
B. Chlorophyll a Sample Bottle
• Move the chlorophyll a sample bottle into position and remove cap.
• Gently shake the container with the sample water to re-suspend any settled material.
• Gently pour the sample water into the chlorophyll a bottle until the liquid reaches the fill
line.
• Cap the chlorophyll a sample bottle and place it into the shipment container with the frizen
ice packs and close the lid so sunlight cannot reach it.
TASKS
Cleanup and shipment of samples and forms.
Volunteers must clean the sampling and laboratory equipment for the next sampling trip. The
Secchi disk and water sampler should be rinsed off with fresh tap water and the sampling
container rinsed with distilled water.
Volunteers must pack and forward the shipping container with the samples to the laboratory as
soon as possible. In addition, the sampling form with the Secchi disk measurement and sampling
observations must be sent to the coordinating agency.
3.G Notes on Equipment
A partial listing of companies that provide equipment and supplies for volunteer monitoring
programs are listed in the appendix. Alternatively, some programs have volunteers construct some
of their own equipment.
Secchi Disks
Some programs have volunteers make their own Secchi disks. A construction plan prepared by
the Michigan Department of Natural Resource's Self-Help Water Quality Monitoring Program is
illustrated here.
Water Samplers
Instead of purchasing commercial water samplers, some programs have volunteers construct their
own.
References
New York State Dept. of Environmental Conservation and Federation of Lake Associations, Inc.
1990.
Diet for a Small Lake: A New Yorker's Guide to Lake Management. Albany.
Olem, H. and G. Flock, eds. August, 1990. The Lake and Reservoir Restoration Guidance Manual.
2nd ed. EPA 440/4-90-006. Prep. N. Am. Lake Manage. Soc. for U.S. Environ. Prot. Agency, Off.
Water, Washington, DC.
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Standard Methods for the Examination of Water and Wastewater. 16th ed. 1985. Am. Pub. Health
Ass., Am. Waterworks Ass., and Water Pollu. Control Fed. 1985. American Public Health
Association. Washington, DC.
U.S. Environmental Protection Agency. August 1990. Volunteer Water Monitoring: A Guide for
State Managers . EPA 440/4-90-010. Off. Water, Washington, DC.
Additional program material on volunteer monitoring of algae can be obtained from the following
State programs:
Florida
Florida LAKEWATCH
79922 NW 71st Street
Gainsville, FL 32606
Illinois
Volunteer Lake Monitoring Program
Division of Water Pollution Control
Illinois Environmental Protection Agency
2200 Churchill Road
P.O. Box 19276
Springfield, IL 62794-9276
Maine
Volunteer Lake Monitoring Program
Division of Environmental Evaluation and Lake Studies
Maine Department of Environmental Protection
State House, Station 17
Augusta, ME 04333
Michigan
Self-Help Water Quality Monitoring Program
Department of Natural Resources
Land and Water Management Division
P.O. Box 30028
Lansing, Ml 48909
Minnesota
Citizen Lake Monitoring Program
Division of Water Quality-Program Development Section
Minnesota Pollution Control Agency
520 Lafayette Road North
St. Paul, MN 55155
New Hampshire
New Hampshire Lakes Lay Monitoring Program
University of New Hampshire
Petee Hall
Cooperative Extension
Durham, NH 03824
New Hampshire Volunteer Lake Assessment Program
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Department of Environmental Services
6 Hazen Drive
Concord, NH 03301
New York
New York Citizens Statewide Lake Assessment Program
New YorkState Department of Environmental Conservation
Division of Water-Lake Services Section
50 Wolf Road, Room 301
Albany, NY 12233-3502
Rhode Island
Watershed Watch Program
Department of Natural Resource Science
21 OB Woodward Hall
University of Rhode Island
Kingston, Rl 02881-0804
Tennessee
TVA Citizen Water Quality Monitoring Program
Tennessee Valley Authority
Water Quality Department
2S-270C Haney Building
311 Broad Street
Chattanooga, TN 37402-2801
Vermont
Vermont Lay Monitoring Program
Department of Environmental Conservation
Water Quality Division
103S. Main Street
Waterbury, VT 05676
Washington
Washington's Citizen Lake Monitoring Project
Department of Ecology
7171 Clean Water Lane, Building 8 MS LH-14
Olympia, WA 98504
Wisconsin
Self-Help Lake Monitoring Program
Wsconsin Department of Natural Resources
Bureau of Water Resources Management
P.O. Box 7921
Madison, Wl 53707-7921
Return to the Table of Contents
Office of Water
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Volunteer Lake Monitoring: A Methods Manual
Chapter 4: Monitoring Aquatic Plants
4.A Aquatic Plant Condition Parameters
In many lakes across the country, an abundance of rooted aquatic plants impairs the use and
enjoyment of recreational waters. A program that focuses on rooted aquatic plants as the lake
condition to be monitored should train citizen volunteers to:
• map the distribution of rooted plants;
• determine the relative density of rooted plant types along a transect line running
perpendicular from shore in select areas; and
• collect specimens for professional identification.
Mapping the Distribution of Rooted Plants
In healthy lakes, several different species of rooted aquatic plants usually occupy the littoral
(shallow) zone. Submergent, rooted floating- leaved, free-floating, and emergent plants are all
important for the overall ecology of a lake. Traveling around the shoreline with a lake map,
volunteers can draw in the location of significant aquatic plant beds and note where growth has
reached the surface. This effort will serve as an historical record for studying changes in
vegetative location. In addition, these maps can be useful for planning the application of aquatic
plant control methods, such as harvesting.
Determining the Relative Density of Rooted Plant Types
It is often useful to take a closer look at the types of rooted aquatic plants in the littoral zone. A
healthy lake usually has many different kinds aquatic plants. Many lakes, however, have littoral
zones that have been disturbed, fertilized, and/or invaded by more aggressive plant species. In
these instances, the least tolerant species are often eliminated and one or two more-tolerant
species begin to take over the zone. In fact, in the majority of lakes where aquatic plant
overgrowths occur, it is the result of a population explosion of only one or two species.
Several exotic plant species (originally from other continents) are notorious for displacing native
plants and dominating the littoral zone. They can become major nuisance problems primarily
because no natural check and balance system controls their growth. A lack of predators and
pathogenic organisms allows exotics to out-compete native species for growing space, light, and
nutrients.
The relative density of different plants growing in the littoral zone can be examined by volunteers.
The method described in this chapter has volunteers collect plants at specific intervals along a
transect line. Addi tionally, the volunteers are directed to measure the length and depth of the
littoral zone along the line.
Identification of Rooted Aquatic Plants
Eurasian watermilfoil (Myriophyllum spicatum ) and water hyacinth (Eichhornia crassipes) are
examples of exotic (non-native) species that can flourish and cause problems in waters of the
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United States. One purpose of a citizen program focused on monitoring rooted aquatic plant
conditions on lakes should be to inventory locations where there are significant amounts of plants.
The identification of plant species is important because the effectiveness of lake management
techniques differ according to plant type. In many instances, the early detection (and elimination)
of aggressive exotic species can save a lake from severe infestation problems later.
The Vermont Department of Environmental Conservation, for example, has established a Milfoil
Watchers Program to train volunteers to identify Eurasian watermilfoil. Then, at least once or twice
a summer, citizens survey lakes where the plant has not been seen. If watermilfoil is spotted,
volunteers contact the department.
4.B Sampling Considerations
The location of sample collection and transect sites in a lake are defined on a lake-by-lake basis
from an initial site visit by the program manager. Some lakes have extensive weed growth
throughout the lake, others have small, well-defined problem areas.
In general, it is best to assign a team of two volunteers no more than four hours of sampling work.
What can be accomplished in this period depends on the size of the lake, the length of the littoral
zone, and the extent of the rooted plants.
In some lakes, the aquatic plant population is relatively stable through out the growing season. In
other lakes, there is a definite pattern of succession. If the lake is small, volunteers may need to
examine plant growth only once or twice a year (in spring and late summer). The program
manager may wish to break a large lake with a significant weed problem into segments and send
volunteers out every two weeks to sample different areas.
The density, diversity, and growth patterns of aquatic plants are unique to each lake. Therefore,
many of the details concerning sample site loca tions and other program aspects must be worked
out by the program man ager on a lake-by-lake basis.
4.C How to Sample
Presented in this section are procedures for mapping the distribu tion of rooted aquatic plants,
collecting, and determining the relative density of plant types along a transect.
Basically, these sampling activities are divided into four main segments.
• Confirming the sampling date and weather conditions and going through boating safety and
sampling equipment checklists prior to launching the sampling boat (Tasks 1 through 3).
• Touring the shoreline and mapping the location of aquatic plants at or near the surface
(Task 4).
• Finding the sampling site, setting up a transect line, collecting plants along that line, and
estimating plant densities (Task 5).
• Returning to shore and shipping the data forms and plant samples (Task 6).
The program manager should provide volunteers with a sampling schedule and a sampling
protocol sheet. Volunteers' common sense and good judgment dictate when it is appropriate to
sample. Both good and unacceptable weather conditions should be defined for volunteers during
training sessions. Under no circumstances should volunteers be on the water during rain or
electrical storms or high winds (white caps), or other unsafe conditions.
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TASK1
Confirm sampling day and weather conditions.
Elements of Task 1
• Check the sampling date on the program sampling schedule.
• Check the current and forecasted weather and decide if the conditions allow for safe
sampling. The volunteer should also be instructed to confirm this decision after personally
inspecting lake conditions prior to launching the boat and beginning the sampling trip.
TASK 2
Go through the boating safety equipment checklist.
Before leaving shore, volunteers must confirm that all the safety equipment is on board. Boating
safety is a subject that volunteers need to take seriously because they will be moving around the
boat, leaning over the edge, and working with equipment.
Volunteers should wear a life preserver (Type 1, 2 or 3 personal flotation) at all times. Volunteers
should educate themselves about safe boating laws and the rules of the road.
Elements of Task 2
• Confirm that the following boating safety equipment are on board the sampling boat:
• A personal flotation device for each person that is Coast Guard-approved, readily available,
and the proper size
• First aid kit
• Other equipment that may be required by State and local boating laws other unsafe
conditions.
TASK 3
Go through equipment and supply checklist for sampling tasks.
Before leaving shore, volunteers must make sure that they have all the needed sampling
equipment.
Elements of Task 3
• Confirm that the following sampling equipment is on board.
• Anchor
• Calibrated transect line (floating line marked off in meters) with anchor and buoy.
• Weighted calibrated sounding line for measuring water depth
• Weighted rake with throwing line
• Plastic bags for plant specimens labeled with the lake name, the date, and the site location
(Transect #1, Site#1).
• Clipboard, pencils and waterproof marker
• Map of lake with sampling site(s) marked
• Protocol sheet
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• Data recording sheets
• Confirm that the shipping box with frozen ice packs is on shore.
TASK 4
Map the location of aquatic plants at or near the surface.
For this task, volunteers must take a tour of the shoreline and observe areas of the lake where
aquatic vegetation is on or near the surface. Using a clean copy of a lake map, volunteers draw a
sketch showing the extent of rooted aquatic plant beds (see m ap on page 63).
TASKS
Estimate plant type density and collect a sample for professional identification.
From shore, the volunteer will locate the sampling site designated by the program manager and
establish a transect line perpendicu larfrom shore. Following along this line at specified intervals,
the volunteer will cast a weighted rake to the lake bottomand pull up aquatic vegetation.
This vegetation will be sorted, and the volunteer will make a qualitative estimate of the percentage
and density of plant types. Specimens of each type will be bagged for shipment to a botanist for
identification.
Elements of Task 5
• Find the designated sampling site and tie the end of the transect line securely to a tree or
stake at the water's edge.
• Move the boat away from shore and stretch the transect line to the desired length.
• Attach the buoy and anchor so that the line remains floating, thus forming the transect.
• Measure and record the lake depth at the end of the transect using the weighted calibrated
sounding line.
• Confirm that the throwing line is securely attached to the weighted rake (can be an ordinary
garden rake).
• Facing the shore, pitch the weighted rake straight ahead (the 12 o'clock position) about six
feet from the boat.
• Allow the rake to settle to the lake bottom and then pull the line so that the teeth of the rake
drag along the floor of the lake.
• Bring the rake back into the boat and remove all the vegeta tion trapped on the teeth. Sort
different plant types into separate piles.
• Examine the piles and estimate the percentage of each plant type found. Record on the
sampling form. The total must add up to 100 percent.
• Repeat the procedure at the 3, 6 and 9 o'clock positions.
• After all four samplings are completed, examine the sorted piles and give each plant type a
density rating. (See the density rating chart on the figure, Example of an Aquatic Plant
Sampling Form on page 67.)
If a plant type was found in all four casts and for each cast the teeth of the rake were full,
mark 5. If the plant was found moderately on all four casts, mark 4. If the plant type was
found in only three of the four casts, mark 3, and so on.
• Remove a few healthy specimens from each of the sorted piles of plant types, shake off
excess water, and place them in a properly labeled collection bag.
• Move the boat along the transect line to the next sampling point and repeat these activities.
(The number of sampling points should be determined by the program manager.)
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• If practical, keep all collected plant fragments in the boat for proper disposal on land since
many nuisance species reproduce from fragments.
TASK 6
Shipment of samples and forms
Volunteers pack and forward the shipping container with the plant type samples to the program
botanist for identification. In addition, the data sheet with the density rating for each plant type
and sampling observations must be sent to the coordinating agency for analysis. Volunteers
should also request additional supplies or equipment as needed.
Elements of Task 6
• Confirm that the bags containing the plant type specimens are securely sealed and properly
labeled.
• Place the bags and ice packs in the mailing box and seal the container.
• Ship the box as soon as possible.
• Confirm that all the sections of the sampling forms have been completed. Write down any
additional observations of activities that may affect sampling results, such as harvesting,
herbicide application, or increased recreation.
• Send the sampling information to the program coordinator.
References
Jessen, R. and R. Lound. 1962. An Evaluation of a Survey Technique for Submerged Aquatic
Macrophytes. Game Investigational Rep. No. 6. MN Dept. Conserv, Div. of Game Fish.
Olem, H. and G. Flock, eds. August, 1990. The Lake and Reservoir Restoration Guidance Manual.
2nd ed. EPA 440/4-90-006. Prep. N. Am. Lake Manage. Soc. for U.S. Environ. Prot. Agency, Off.
Water, Washington, DC.
State of Michigan Dept. of Natural Resources. December, 1987. Common Aquatic Plants of
Michigan. Land Water Mgt. Div., Lansing, Ml.
U.S. Environmental Protection Agency. August 1990. Volunteer Water Monitoring: A Guide for
State Managers . EPA 440/4-90-010. Off. Water, Washington, DC.
Additional program material relating to volunteer monitoring of aquatic plants is available from
these States:
New York
New York Citizens Statewide Lake Assessment Program
New York State Department of Environmental Conservation
Division of Water - Lake Services Section
50 Wolf Road, Room 301
Albany, NY 12233-3502
Vermont
Vermont Lay Monitoring Program
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Department of Environmental Conservation
Water Quality Division
103S. Main Street
Waterbury, VT 05676
Office of Water
Volunteer Lake Monitoring: A Methods Manual
Chapter 5: Monitoring Dissolved Oxygen
5.A Dissolved Oxygen Parameters
The amount of dissolved oxygen in the water is an important indicator of overall lake health. When
oxygen is reduced, organisms are stressed. When oxygen is absent, all oxygen-breathing life
forms must either move to an oxygenated zone or die.
There are also many chemical reactions that occur depending on whether or not oxygen is in the
water. For example, an essential plant nutri ent, phosphorus, can be released from bottom
sediments when oxygen is reduced in the lower layer of a lake.
Dissolved oxygen conditions are best characterized by measuring the:
• dissolved oxygen profile (measurements from the surface to the bottom at set intervals); and
• temperature profile (at the same intervals).
Dissolved Oxygen Profile
When characterizing the oxygen condition in a lake, it is important to know how oxygen
concentrations differ from the surface to the bottom. In lakes that have a problem with low
dissolved oxygen, it is not unusual to measure high dissolved oxygen levels at the surface during
the day because algae in the photic zone are photosynthesizing and producing oxygen. At night,
these same algae respire and consume oxygen.
Near the bottom, however, there may be low or no oxygen because decomposers are absorbing it
while breaking down the "rain" of organic matter (dead algae cells, zooplankton, fish) falling from
above.
A profile of oxygen measurements taken from top to bottom may provide insight on the relative
populations of oxygen-producing plants and bottom -dwelling decomposers.
Temperature Profile
Water temperature plays an important role in determining the amount of oxygen found in the lake.
Oxygen is more soluble in cold than warm water. Most lakes over 20 feet deep stratify during the
summer into a warm, lighted upper layer (epilimnion) and a cold, dark lower layer (hypolimnion).
Thus, the cold lower layer can potentially hold more oxygen than the warmer upper layer.
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Usually these layers do not mix; thus, the bottom layer is cut off from atmospheric oxygen and
oxygen-producing plants. Consequently, bottom oxygen can become depleted if there is an active
population of decomposers in the bottom sediments. For these reasons, it is important to define
the thermal layers in a lake when characterizing dissolved oxygen conditions.
5.B Sampling Considerations
Temperature and oxygen profiles should be taken at a site directly over the deepest portion of the
lake basin. If the lake has several distinct basins, the program manager may require volunteers to
sample each at the deepest location.
Temperature and oxygen profile measurements should begin with spring overturn. At that time,
both temperature and oxygen concentration are uniform from top to bottom in most lakes.
Sampling should continue throughout the summer season. It may be even useful to extend the
program to fall overturn.
To track the progress of oxygen depletion in the lower layer, sampling should be conducted every
two weeks. In some cases, it may be useful to build some flexibility into the program and
encourage volunteers to gather profile data after large, windy storms. This effort will document
whether lake stratification breaks down under storm or high wind conditions.
Additionally, if there is a large crop of aquatic weeds or algae, the plan ning committee may wish
to have volunteers sample the oxygen concen tration in the photic zone in the early morning to
evaluate the impact of nighttime respiration.
There are two methods of measuring dissolved oxygen in a lake. Volunteers can use a dissolved
oxygen field kit, or a submersible oxygen meter.
Field kits are available from many manufacturers. All kits basically require that volunteers take a
water sample and analyze dissolved oxygen using a titrimetric procedure. The sample must be
analyzed immediately after collection.
To get meaningful results, volunteers must observe strict sample handling protocol. Contact with
the air, agitation, exposure to strong sunlight, and temperature and pressure changes will affect
the oxygen content of a sample.
These factors, plus the fact that several dissolved oxygen measure ments are needed to make up
a profile, makes the use of field kits generally unsuitable for volunteer programs that are
monitoring the dissolved oxygen profile in lakes. If the goal of the program, however, is to simply
sample oxygen in the photic zone and not create a full water column profile, a dissolved oxygen
kit may be an attractive and less expensive alterna tive.
The most convenient method for taking both oxygen and temperature profiles, however, is to use
a portable oxygen meter that incorporates a thermistor. The meter displays a dissolved oxygen
readout based on the rate of diffusion of molecular oxygen across a membrane. The thermistor
component of the instrument provides a temperature readout.
Each meter manufacturer provides detailed instructions on sampling protocol and how and when
to calibrate the meter to obtain guaranteed precision and accuracy. Calibration should be done by
experienced program personnel at the manufacturer-recommended intervals. This means the
instrument will have to be transported between the volunteer and program officials between those
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intervals.
For convenience, citizen monitoring programs can purchase a meter with a permanent membrane
to avoid having to calibrate it before each trip.
5.C How to Sample
Suggested procedures for measuring temperature and oxygen profiles of a lake are described in
this section. Sampling activities can be divided into three sections:
• Confirming the sampling date and weather conditions and going through boating safety and
sampling equipment checklists prior to launching the sampling boat (Tasks 1 through 3).
• Finding the sampling site and documenting observations about water and weather
conditions (Tasks 4 and 5).
• Taking a temperature and oxygen profile, entering the readings on the sampling form, and
then mailing the form to program officials (Tasks 6 - 8). To take a profile measurement,
lower a thermistor and oxygen probe on a calibrated cable through the water column. At
specified intervals, read and record the temperature and dissolved oxygen concentration.
• The program manager should provide a sampling schedule and a sampling protocol sheet
to volunteers. In general, monitors should be in structed to conduct sampling between 10
a.m. and 3 p.m. Volunteers must understand, however, that there is flexibility in both the
day and time, especially in consideration of weather conditions.
• Volunteers' common sense and good judgment should dictate when it is appropriate to
sample. Both good and unacceptable weather conditions should be defined during training
sessions. Under no circumstances should volunteers be on the water during rain or
electrical storms, high winds (white caps), or other unsafe conditions.
TASK1
Confirm sampling day and weather conditions.
Elements of Task 1
• Check the sampling date on the program sampling schedule.
• Check the current and forecasted weather and decide if the conditions allow for safe
sampling. The volunteer should also be instructed to confirm this decision after personally
inspecting lake conditions prior to launching the boat and beginning the sampling trip.
TASK 2
Go through the boating safety equipment checklist.
Before leaving shore, the volunteer must confirm that all the safety equipment is on board.
Boating safety is a subject that volunteers need to take seriously because they will be moving
around the boat, leaning over the edge, and working with equipment.
Volunteers should wear a life preserver (Type 1, 2, or 3 personal flotation device) at all times.
Volunteers should
Elements of Task 2
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• Confirm that the following boating safety equipment are on board the sampling boat
• A personal flotation device for each person that is Coast Guard-approved, readily available,
and the proper size.
• First aid kit
• Other equipment that may be required by State and local boating laws
TASK 3
Go through equipment and supply checklist for sampling tasks.
Before leaving shore, volunteers must confirm that they have all the needed sampling equipment.
Elements of Task 3
• Confirm that the following sampling equipment and supplies are on board the boat.
• Anchor (with a measured line if a depth check is required). Two anchors are helpful on
windy days.
• Weighted calibrated sounding line for measuring depth
• Clipboard and pencils
• Map of lake with sampling site and landmarks marked
• Sampling protocol sheet
• Sampling form
• Dissolved oxygen meter with thermistor
TASK 4
Position boat at the designated sample site.
The volunteer must locate the sample site on the water. Whether or not a marking buoy is used,
the position should be verified using a shoreline landmark method (described in Chapter 3).
Once the site is located, the volunteer can anchor the boat. Reposition ing the anchor once it is
dropped should be discouraged, especially in shallow lakes, because it can stir up sediments
from the lake bottom. Increasing sediment turbidity may alter the data collected at the site.
After anchoring, volunteers should allow the boat to become stable.
Reporting visual conditions such as water color and appearance will aid in the interpretation of
data results. For example, if the sampling trip was conducted after a storm, thermal stratification
may have broken down and caused mixing of the layers.
TASKS
Complete the observations portion of the sampling form.
Volunteers should record their observations about the lake and weather conditions on the
sampling form. Elements of Task 5
• Record the lake and site name, the date, the time of sampling, and the names of volunteers
doing the sampling.
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• Record weather and water condition observations.
• Record any other factors or conditions that make the sam pling trip unusual or may
potentially influence results. For example, report any chemical, mechanical, or biological
control of algae or rooted aquatic plants.
TASK 6
Measure the depth of the site.
Using the weighted calibrated sounding line, volunteers should measure the depth of the site and
record it on the sampling form. It is important to know the depth because the oxygen probe must
not be allowed to come in contact with the lake bottom.
TASK 7
Measure the temperature and dissolved oxygen profile.
The thermistor and oxygen probe is lowered into the water at the specific intervals designated by
the program manager. Volunteers will record readings on the data form.
Elements of Task 7
• Check to make sure that the oxygen probe is securely attached to the measured line.
• Lower the probe into the water just below the surface, let the probe acclimate according the
manufacturer's instructions, take a temperature and oxygen reading, and record it on the
data sheet.
• Lower the thermistor tvo the next deeper interval and repeat these steps.
• Continue to collect readings at each interval until the probe is approximately one to two
meters above the bottom.
TASKS
Ship forms.
This task requires volunteers to forward the data sheet with the temperature and oxygen profile
data and the observation information to the coordinating agency.
References
Olem, H. and G. Flock, eds. August, 1990. The Lake and Reservoir Restoration Guidance Manual.
2nd ed. EPA 440/4-90-006. Prep. N. Am. Lake Manage. Soc. for U.S. Environ. Prot. Agency, Off.
Water, Washington, DC.
Standard Methods for the Examination of Water and Wastewater. 16th ed. 1985. Am. Pub. Health
Ass., Am. Waterworks Ass., and Water Pollu. Control Fed. 1985. American Public Health
Association. Washington, DC.
U.S. Environmental Protection Agency. August 1990. Volunteer Water Monitoring: A Guide for
State Managers . EPA 440/4-90-010. Off. Water, Washington, DC.
Additional program material relating to the monitoring of dissolved oxygen and temperature is
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available from the following States:
New York
New York Citizens Statewide Lake Assessment Program
New York State Department of Environmental Conservation
Division of Water-Lake Services Section
50 Wolf Road, Room 301
Albany, NY 12233-3502
Tennessee
TVA Citizen Water Quality Monitoring Program
Tennessee Valley Authority
Water Quality Department
2S-270C Haney Building
311 Broad Street
Chattanooga, TN 37402-2801 79
Office of Water
Volunteer Lake Monitoring: A Methods Manual
Chapter 6: Monitoring Other Lake Conditions
6.A Monitoring Sedimentation
Sedimentation problems occur when erosion is taking place in the watershed. Surface runoff
washes sand and silt into the lake where it settles to the bottom and creates shallow areas that
interfere with lake use and enjoyment. In addition, sediments often carry significant amounts of
nutrients that can fertilize rooted aquatic plants and algae.
Citizens can characterize the build-up of sediments by measuring water depth and the depth of
unconsolidated (soft bottom) sediments in key areas (mouths of tributary streams or near an
eroding shoreline). In this manner, a historical record of sedimentation can be developed.
To measure sediment, set up a transect line and sample at specified intervals along it. A basic
procedure involves the use of two dowels (probes) about one inch in diameter and long enough to
stick above the surface at the deepest point of measurement. Securely attached to the bottom of
one probe is a nine-inch plate (a pie pan works well). Both probes are calibrated in meters and
tenths of meters.
Working along a transect line, volunteers can:
• locate the sample site along a transect;
• measure and record the depth of the water from the surface to the
top of the sediments using the probe with the plate on the end;
• push the other probe into the sediments until first refusal (it becomes hard to push) and
measure and record the depth. The difference between the two depths is the thickness of
the unconsolidated sediments. The number of transects and the location of sites along
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those transects will be decided by the planning committee. By participating in a sediment
recording program, the volunteers will gain appreciation that erosion and sedimentation is
an important lake management problem.
6.B Monitoring Suspended Sediment
Some of the silt and organic matter that enters a lake does not settle to the lake bottom. Instead it
remains suspended in the water. These sus -pended solids decrease water transparency and can
affect the suitability of the lake habitat for some species. In addition, solids often carry in
significant amounts of nutrients that fertilize rooted aquatic plants and algae.
Total solids is a term used to describe all the matter suspended or dissolved in water.
Total suspended solids is that portion of the total solids that are retained on filter paper after a
sample of water is passed through.
Citizens can monitor the suspended sediment condition by measuring two parameters:
• water transparency using a Secchi disk; and
• total suspended solids.
The Secchi disk is a instrument that measures water clarity. The reader is referred to Chapter 3 of
this manual for a thorough explanation of its use in lake monitoring.
The concentration of total suspended solids in a water sample is analyzed in a laboratory.
Procedures involve the use of a filtering appara tus, a special drying oven that can maintain a
constant temperature between 103° and 105° F and a sensitive analytical balance capable of
weighing material to 0.1 milligrams. In most cases, volunteers will take a grab sample just below
the surface in an area designated by the planning committee. The sample must be kept cold and
shipped to the laboratory as soon as possible after collection to minimize microbiological
decomposition of solids. This monitoring is particularly useful for analyzing trends in suspended
material after storm events. For this reason, the planning commit tee may wish to instruct
volunteers to sample on a two-week schedule for baseline purposes and then to conduct
additional sampling after storms.
6.C Monitoring Acidification
A citizen monitoring program that focuses on lake acidification usually examines:
• pH, a measure of lake acidity status; and
• alkalinity, a measure of the acid neutralizing capacity of a substance.
The pH is measured on a scale of 0 to 14. The lower the pH, the higher the concentration of
hydrogen ions and the more acidic the solution. Acid rain typically has a pH of 4.0 to 4.5. In
contrast, most lakes have a natural pH of about 6.0 to 9.0.
Alkalinity, or acid-neutralizing capacity, refers to the ability of a solution to resist changes in pH by
neutralizing acid input. In most lakes, buffering is accomplished through a complex interaction of
bicarbonates, carbonates, and hydroxides in the water. The higher the alkalinity, the greater the
ability of the water to neutralize acids.
Lakes with low alkalinity are not well buffered. These lakes are often adversely affected by acid
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inputs. After a short time, their pH levels will drop to a point that eliminates acid-intolerant forms of
aquatic life. Fish are particularly affected by low pH waters.
The planning committee can designate pH and alkalinity sampling to occur at the lake's center or
at special areas of interest. The depth where samples are taken can vary with program objectives,
but one meter is usually sufficient for a general characterization of a lake.
Sampling should occur from spring overturn until the end of the summer season. Both pH and
alkalinity are affected by biological activity; there fore, the planning committee may direct
volunteers to sample every two weeks. The time of the day that the sample is taken should be
noted on the sampling form. The pH normally rises during active photosynthetic periods.
The pH of a lake sample can be easily determined by using a portable, battery-powered pH
meter. In general, pH meters are accurate and easy to use. However, they do need to be
calibrated at regular intervals accord ing to the manufacturer's instructions. Training on both
meter use and calibration is important. A pH meter can also be used in the analysis of alkalinity.
As an alternative to a pH meter, volunteers can use a pH test kit. To conduct the test, volunteers
add an indicator dye to a measured amount of water sample. The dye produces a color based
upon the pH. Volunteers can then compare the color with a standard color of a known pH.
The pH test kits come in several varieties. Some can test for a wide pH range, others are designed
to test narrow ranges. It is best to know the approximate pH of the lake to be sampled and choose
the kit best suited to the planning committee's purpose. The program manager should plan to
conduct regular quality control checks because when the dyes age, they sometimes give
erroneous results.
The objectives of the volunteer monitoring program, economic considerations, and the data quality
requirements of the users will guide the decision on whether to use a colorimetric test kit or a pH
meter.
The other parameter used to characterize a lake's acidification condition is alkalinity. Volunteers
can measure alkalinity in the field by using a test kit. The procedure involves monitoring the
changes in pH of a water sample as an acid is dripped into it. Volunteers calculate alkalinity
based on the amount of acid it took to reach an end point pH.
The end point pH for determining alkalinity varies according to the approximate actual alkalinity of
the sample.
When titrating, the end point pH can be determined in two basic ways:
• by using a pH meter; or
• by mixing a standard indicator solution into the sample and watching for a color change that
will occur when the desired end point pH is reached.
There are several kits on the market that can be used to measure alkalinity. Each kit has its own
procedures that should be followed carefully.
As with pH, the objectives of the volunteer monitoring program and the data quality requirements
of the program customers will guide the decision on which test kit to purchase.
The Gran analysis method is an alternative technique for charac terizing a lake's acidification
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condition. Commonly used in scien tific studies of acidic deposition, the method provides
information, referred to as acid neutralizing capacity because it includes carbonate, bicarbonate,
and hydroxide alkalinity plus the additional buff ering capacity of organic acids and other
compounds.
6.D Monitoring Bacteria at Bathing Beaches
A wide variety of disease-causing organisms can be transmitted to humans at bathing beaches.
Sources of pathogens include sewage, runoff from animal or wildfowl areas, and even swimmers
themselves.
Because of the risk of waterborne disease, it is good public health practice to test beaches
periodically during the swimming season. Public health officials usually monitor for the presence
of one or more indicator organisms as part of a regular sampling program. The relative abundance
of an indicator organism found in a water sample serves as a warning for the likely presence of
other, more dangerous pathogens in the water.
The indicator organisms most often used to indicate sanitary conditions at bathing beaches are:
• fecal coliform bacteria; and
• enterococcus bacteria.
Coliforms belong to the enteric bacteria group, Enterobacteriaceae, which consists of various
species found in the environment and in the intestinal tract of warm-blooded animals. Fecal
conforms are the part of the coliform group that are derived from the feces of warm-blooded
animals. The fecal test differentiates between conforms of fecal origin and those from other
sources.
Enterococcus are a subset of the fecal coliform group. Like fecal conforms, they, too, indicate
fecal contamination by warm-blooded animals. They are useful because they are found only in
certain animals. Examination of the ratio of fecal coliform to enterococcus can, there fore, indicate
whether the bacterial pollution is from humans or animals.
Most public health officials recommend weekly testing of swimming beach areas. Sampling
should occur at one or more sampling sites in water three to four feet deep. A sterilized sampling
bottle should be prepared by the laboratory.
The number of sites needed will vary with the length and configuration of the beach. One site is
generally adequate if the beach shoreline is 300 linear feet or less. If the shoreline is between 300
and 700 linear feet, a minimum of two sites is recommended. A beach shoreline greater than 700
feet requires three or more sample sites.
There are six steps in most basic procedures:
• Remove the cap from a sterile collection bottle without touching the inside of the cap or the
inside of the bottle.
• Grip the bottle at the base and plunge it in a downward motion into the water to a depth of
12 to 18 inches.
• Using a forward sweeping motion (so water is not washed over the hand into the bottle),
invert the bottle and bring it to the surface.
• Empty it slightly to leave approximately one inch of air at the top.
• Re-cap the container, then label and store it at a temperature between 39° and 45° F.
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• Transport the bottle to the laboratory as soon as possible after sampling.
Sampling for bacteria at beaches should be conducted under the auspices of the local health
department. Analysis should be done at a certified laboratory. If a problem is found, program
officials should notify health authorities for follow-up testing and mitigation activities.
The sampling protocol for monitoring bacteria concentrations at natural bathing beaches will also
vary according to program objectives and the requirements of data users who, in many instances,
are officials of the local health department. Most health dep artments have strict criteria and
procedures that must be followed when sampling for indicator organ isms like fecal coliform or
enterococcus bacteria. The volunteer sampling protocol, therefore, must follow the protocol used
by the health depart ment. References
Connecticut Dept. of Health Services. 1989. Guidelines for Monitoring Bathing Waters and Closure
Protocol. CT Dept. Environ. Prot., Hartford.
Olem, H. and G. Flock, eds. August, 1990. The Lake and Reservoir Restoration Guidance Manual.
2nd ed. EPA 440/4-90-006. Prep. N. Am. Lake Manage. Soc. for U.S. Environ. Prot. Agency, Off.
Water, Washington, DC.
Standard Methods for the Examination of Water and Wastewater. 16th ed. 1985. Am. Pub. Health
Ass., Am. Waterworks Ass., and Water Pollu. Control Fed. 1985. American Public Health
Association. Washington, DC.
U.S. Environmental Protection Agency. August 1990. Volunteer Water Monitoring: A Guide for
State Managers . EPA 440/4-90-010. Off. Water, Washington, DC.
87
Office of Water
Volunteer Lake Monitoring: A Methods Manual
Chapter 7: Training Citizen Volunteers
7.A The Training Process
Training the volunteers to do their jobs properly is an essential component of a successful
monitoring program. Significant amounts of time and resources should be budgeted specifically to
plan, present, and evaluate volunteer training.
The payoff from effective volunteer training rises well above the initial costs. From the program
manager's perspective, good training means less time and energy spent answering and
re-answering basic procedural questions.
From the volunteers' perspective, effective training stimulates confi dence and increases the
desire to do the job right. In addition, the data collected by well-trained volunteers tend to be of
higher quality and thus more valuable to users.
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Training is a dynamic process. It does not simply begin and end with a kickoff classroom session
for new volunteers. For example, follow-up training must occur to resolve specific operating
problems discovered in an on-going program.
Even experienced volunteers benefit from occasional continuing education sessions, which help
everyone stay in touch with the program and foster the ideal of team effort.
The planning committee should plan volunteer training from three basic perspectives:
• training new volunteers;
• training experienced volunteers (about new equipment, improved methods, or simply to
provide a refresher course on sampling protocol); and
• solving specific operating problems.
Each of the three training perspectives requires the presentation of unique material. The training
processes involved in presenting this material, however, are similar.
Basically, the volunteer training process can be broken down into five phases.
Phase 1: Creating a Job Analysis
Phase 2: Planning the Training
Phase 3: Presenting the Training
Phase 4: Evaluating the Training
Phase 5: Conducting Ongoing Coaching, Motivation, and Feedback
Each of these phases are discussed in the following sections.
7.B Creating a Job Analysis
The job analysis phase is the hardest yet the most important part of training development. The job
analysis is a list of all the tasks volunteers must accomplish when sampling a parameter. Its
purpose is to ensure that sampling procedures are performed by volunteers consistently
throughout all the program lakes.
When job tasks are performed with consistency:
• quality standards can be developed;
• time and cost requirements can be evaluated;
• performance evaluation criteria can be developed; and
• the data user can have greater confidence in the data results (especially when comparing
the data from one lake with another).
There are four steps in creating a job analysis:
• developing a list of sampling tasks;
• determining the required quality level for each task;
• defining the job elements that comprise each task; and
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• creating a sample protocol or job description handout for the volunteers.
The sampling protocols presented in the previous chapters can be used as a basic outline for
creating job analyses. The planning committee can take the job tasks, quality levels, and
elements described in the chapters and add the detail unique to the operation of their individual
program.
The job description handout is an important product of this phase. An overall objective of this job
description is to provide each program volunteer with clear instructions of what to do when
performing each monitoring task.
A well-written handout can have several other uses, as well. For example, the job description:
• can be used as a volunteer recruitment tool. (Potential volunteers can preview the tasks
involved before committing to the program);
• can serve as the basic outline for planning a training session; and
• can be used as a management tool for supervising and evaluating volunteer performance.
Once a job description is proposed, members of the planning committee (and a few volunteers)
should test it in the field. The feedback will be useful in fine-tuning the job description document.
7.C Planning the Training
Once the job analysis is completed and a job description prepared, the planning committee can
start designing the actual training session. The committee must decide if the training is to occur in
a group setting or on a one-on-one basis.
Group training saves money and time, especially when there are many volunteers who must be
trained simultaneously. This approach has its drawbacks because every lake has unique
characteristics. Thus, there may be circumstances or problems that can be addressed only on an
individual basis.
For example, training the volunteer to locate a sampling site is best done on that lake.
One-on-one training is more time consuming and expensive but allows program managers to
instruct and demonstrate procedures under actual conditions experienced by the volunteer. For
those programs operating under strict quality assurance/quality control guidelines, individual
one-on-one training is essential.
In practice, it is often best to structure the training program so that there are group sessions as
well as individual follow-up sessions for each lake. Given this scenario, the group presentation
can be used to introduce program personnel and educate the volunteers about the following
topics:
• purpose, goals, and objectives;
• basic lake ecology, preservation, and management;
• how the collected data will be used and by whom;
• the role of volunteers;
• lake condition being monitored;
• parameters to monitor the condition;
• procedures to measure the parameters;
• distribution and preparation of the sampling equipment; and
• how the results are reported to the data users and to the volunteers.
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On-lake follow-up sessions will reinforce what was taught in the classroom and allow program
officials to adapt any special variations of training protocol. Topics such as how to find a sampling
site and how to prepare samples for shipment can be discussed and practiced at the actual
locations.
In most instances, the job description document will serve as the foundation of the training
session. Thus, the training session can be broken down into a series of mini lessons designed to
teach the skills needed to perform each of the tasks in the job description. An example of how to
plan a mini lesson is presented on the following pages.
Sample Mini Lesson:
Secchi Disk
The content and activities of the mini lesson need to be planned so that the task is covered
thoroughly within the time allotted. The lessons should include volunteer participation wherever
possible. Active participation usually stimulates questions and enhances the learning experience.
Training Topic: Measuring Algae
Mini Lesson: Taking a Secchi disk measurement
Objective: To train volunteers how to use a Secchi disk and record the reading on the data sheet.
Time Allotted: 30 minutes
Equipment: Secchi disks (to be distributed to volunteers)
Rope lines (to be attached by the volunteers)
Clothes pins
Data sheet Pencils
Topic A: Introduce the Secchi disk
• Distribute the equipment to the volunteers.
• Explain that the basic purpose of the Secchi disk is to measure water transparency.
• Discuss the historical significance of the Secchi disk mea surement.
• Explain standard characteristics of the disk.
Topic B: Note factors influencing water transparency readings
• Have the volunteers name factors that may influence Secchi disk readings (eyesight/glare or
water reflection/cloud cover/algae in the water/sediment/waves).
• Discuss the factors that influence readings.
Topic C: Purpose of the Secchi disk measurement
• Discuss how the Secchi disk data collected by the volunteers will be used and by whom.
• Discuss the importance of data quality.
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Topic D: How to take a Secchi disk measurement
• Demonstrate how a reading is taken.
• Discuss the range of Secchi disk depths likely to be encountered in the field.
Topic E: Attaching, marking, and flagging the line
• Demonstrate how the line is tied to the Secchi disk.
• Demonstrate how a Secchi disk line is measured and marked (in inches).
• Demonstrate how to attach and label duct tape flags to the line at six-inch intervals.
• Instruct the class to attach, measure, mark, and flag their Secchi disk lines.
Topic F: Learning the motions
• Demonstrate the task of making Secchi disk measurements (including placing the clothes
pins on the line at the point the Secchi disk disappears and reappears).
• Instruct the class to practice attaching the clothes pins to the line and making a reading.
Topic G: Filling out the data sheet
• Demonstrate how to record the Secchi disk measurement on the data sheet.
Topic H: Quality control
• Discuss standard operating procedures (including the impor tance of taking the
measurement on the shady and calm side of the boat, not wearing sunglasses, and so
forth).
Topic I: Closing the lesson
• Review the Secchi disk measurement procedure and ask for questions.
7.D Presenting the Training
The time and effort spent on the first two phases of volunteer training pay off during the third
phase, the presentation. Volunteers appreciate a well-organized and well-paced training session.
There are four steps that go into presenting an effective training session:
• preparation,
• presentation,
• demonstration, and
• review.
Preparation
There is nothing more important than good preparation. The lesson planning phase discussed in
the previous section will provide the trainer with the basic agenda for the session. The trainer,
however, will have the responsibility to adapt the lesson to the expectations, knowledge, and
experience of the audience. An effective trainer, for example, will prepare separate sessions for
new volunteers and experienced volun teers.
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The person presenting the training must know the material and be organized. Lectures, activities,
and discussions should be planned and kept to a timetable.
Similarly, demonstration materials, audio/visual equipment, and handouts must be accessible and
easily incorporated into the presentation. The trainer must be able to anticipate and respond to
problems and questions that may occur during an actual training session.
The trainer must always rehearse the session to work out any presentation bugs. Additionally,
members of the planning committee should be given an opportunity to critique the performances
of the trainers.
Presentation
Given all the planning and preparation work that goes into it, the actual presentation may be the
easiest part of the whole training process. A relaxed presentation that fulfills the education
objectives is the basic goal. While trainers will bring their own styles to the training session, there
are basic public speaking techniques that should be used, which include:
• establishing rapport with the audience;
• enunciating clearly and distinctly;
• using effective body language;
• using eye contact; and
• encouraging questions and comments.
Demonstration
Whether in the classroom or in the field, volunteers must be allowed to demonstrate what they
have learned. The trainer should observe volunteers closely and offer immediate feedback in
terms of positive reinforcement or corrective assistance. This portion of the session is usually
when the real learning takes place.
Review
During the review portion of the training session, the trainer summa rizes what was learned and
the audience is given an opportunity to ask questions. The session should close with the
reassurance that volunteers will continue to receive training through out their tenure with the
monitoring program.
7.E Evaluating the Training
Has the training been successful? Have the learning objectives been met? The trainer and
planning committee will never know unless the training is evaluated.
Training evaluation encompasses the entire training process and in eludes the volunteer's
perspective as well as that of the planning committee.
Basically, training evaluation focuses on:
• training methods,
• training content, and
• training environment.
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To gain immediate feedback about training, have volunteers fill out evaluation forms at the end of
the session. Perhaps more effective, however, is to observe volunteers in action during the
sampling season. If there are problems or if techniques are not performed according to desired
sampling protocol, trainers may need to apply new methods in subsequent training sessions.
7.F Follow-up Coaching, Motivation, and Feedback
As stated previously, training is conducted throughout the life of the monitoring program.
Follow-up coaching is an integral part of the training process.
Coaching usually occurs on a one-on-one basis and serves many pur poses. Specifically, it:
• maintains communication between the volunteer and program officials;
• allows the volunteer to ask questions and resolve problems;
• motivates the volunteer and conveys a sense of teamwork; and
• provides a format for implementing new or improved sampling techniques.
The key to follow-up coaching is personal contact. In many cases, however, it is enough to call
volunteers periodically to find out how they feel the program is going and ask if they have
questions. This personal touch, which increases volunteer satisfaction, should be maintained
throughout the life of the program.
The companion manual to this document, Volunteer Water Monitoring: A Guide for State
Managers, discusses several other ways to maintain volun teer interest. These techniques include:
• sending volunteers regular data reports;
• keeping volunteers informed about all uses of their data;
• preparing a regular newsletter;
• having program officials be easily accessible for questions and requests;
• providing volunteers with educational opportunities;
• keeping the local media informed of the goals and findings of the monitoring effort;
• recognizing the efforts of the volunteers through certificates, awards, or other means; and
• providing volunteers with opportunities to grow with the program through additional training,
learning opportunities, and changing responsibilities.
References
Zaccarelli, H.E. 1988. Training Managers to Train: A Practical Guide to Improve Employee
Performance. Crisp Publ., Inc., Los Altos, CA.
U.S. Environmental Protection Agency. August 1990. Volunteer Water Monitoring: A Guide for
State Managers . EPA 440/4-90-010. Off. Water, Washington, DC.
Office of Water
Volunteer Lake Monitoring: A Methods Manual
Chapter 8: Presenting Monitoring Results
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8.A Overview of Data Presentations
One of the basic tenets of successful volunteer monitoring programs is that sampling data must
be properly analyzed and presented. Volunteers need to see their sampling data interpreted and
presented as findings if they are to maintain their interest in the program. Organizing agencies
and other data users also need to see that the program is generating useful information.
Techniques for presenting volunteer data may vary depending on the technical background of the
target audience. This chapter will focus on reporting monitoring results to those citizen volunteers
who participate in the program; however, the methods that a re-outlined here should prove useful
to other data users as well.
The Importance of Credible Data
Volunteer monitoring programs must ensure that data released to the public are absolutely
accurate. Misinformation can occur when data are too hastily or sloppily collected, stored,
analyzed, or presented. When this happens, the credibility and hence, the utility of the volunteer
program is thrown into question.
To ensure that volunteer-collected data are credible and defensible, program managers must
carefully plan and maintain a quality assurance program. Approved data collection methods must
be established and followed; data must be stored and documented according to specific quality
assurance protocols; incoming data must be constantly reviewed; and staff time should be
committed in advance to conduct concise, clear, accurate analyses and presentations of
volunteer-collected data. Further information on these quality assurance considerations is
available in the EPA document, Volunteer Water Monitoring: A Guide for State Managers .
Presenting the Data
Some citizen monitoring programs issue annual reports at the end of the sampling season.
Others rely on regularly-issued newsletters or bulletins. Whatever the format, it is always
important to keep in mind the interest, background, and level of technical understanding of the
target audience.
Three rules apply when presenting data to volunteers.
• The data presentation should not be overly technical or insultingly simple. Graphics are
extremely helpful.
• The data presentation should convey information with a specific purpose in mind (e.g., to
show a trend, to illustrate seasonal variations or variations with depth, or to identify problem
sites).
• The data presentation must be timely and relevant to the lake condition. Volunteers and
other data users will lose interest in the program if significant delays occur between the
sampling season and the presentation of data results.
It is not enough to simply list the data when preparing a summary report for volunteers. Instead,
the author of the report should use an appropriate combination of graphs, summary statistics,
maps, and narra tive interpretation. Some common options for presenting the data are discussed
below.
Graphs
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Choosing a graphic format that will best transfer information about the monitoring data requires
careful thought. Three basic types of graphs are often used to present volunteer monitoring
information:
• bar graph,
• pie graph, and
• line graph.
The bar graph uses column bars of varying lengths to compare data. This graph places special
emphasis on individual values in the data set rather than overall trends.
The pie graph compares parts to the whole. In a pie graph, each value in the data set is
represented by a wedge in a circular pie. The pie as a whole equals 100 percent of the total
values in the data set. The size of any individual wedge, therefore, corresponds to the percentage
that the value represents to the total.
The line graph effectively shows changes (or trends) over a period of time or space. Unlike bar
graphs, it does not place emphasis on the individual values in the data set.
Listed below are some basic rules when creating graphs.
• Prepare the graph with an informational purpose in mind.
• Limit the number of elements used in the graph. The number of wedges in a pie graph
should be five or less. The bars in a bar graph should fit easily. Limit the number of
overlaying lines in a line graph to three or fewer.
• Expand elements to fill the dimensions of the graph. Unless there is a specific reason to
emphasize magnitude or scale, trends and patterns can be distorted if the graph is off
-balance. Strive to balance the height and width so that information is represented
accurately.
• Choose scales that quickly and easily illustrate values.
• Title the graph to describe clearly what it presents.
• Label the axes clearly and do not overcrowd points along axis lines.
• Use a legend (or key) when appropriate.
• Present information concerning sampling time or conditions when appropriate.
Summary Statistics
Summary statistics are useful for conveying information about a data set. These statistics should
succinctly, yet efficiently, transfer facts about the measured variable.
Textbook statistics assume that if a parameter is measured a large number of times under a
common universe of circumstances, the measurement values will be distributed at random around
an average value. If the relative frequency of these values are plotted against value magnitude,
the result will be the familiar Gaussian (normal or bell-shaped) curve. The specific shape of this
curve is defined by two statistics, the mean (or average) of the data set values and the standard
deviation.
The mean is a statistic that describes the central tendency of the data set. Standard deviation
describes the variability or spread of the data around the mean. Traditionally, the mean and
standard deviation are the statistics used to summarize a set of lake data.
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In practical application, however, the mean and standard deviation are not always the appropriate
summary statistics to use because lake data do not usually follow textbook patterns of normal
distribution around an average value. Instead, the data are frequently skewed in one direction or
the other.
This skewness occurs because there are many important factors that influence lake conditions,
including the changing seasons, weather condi tions, and activity in the lake and watershed. As a
result, the parameters used to describe lake conditions are constantly in a state of flux.
Thus, skewness can usually be expected, especially when measuring the parameters that
characterize an algal condition (Secchi disk transpar ency, chlorophyll a, and total phosphorus
concentration). Chlorophyll a concentration, for example, may go through several cycles each
year. It may be low in the spring, high during a mid-summer algae bloom, and low again in the
fall.
Robust Statistics
Whenever there is an irregular or uncertain pattern of data values for a lake parameter, robust
summary statistics should be used. A robust statistic conveys information under a variety of
conditions. It is not overly influenced by data values at the extremes of the data distribution.
Median and interquartile range are robust statistics that describe central tendency and spread
around the median, respectively. Both these summary statistics are unaffected by extreme points.
Consequently, they are usually more appropriate for summarizing lake data than the traditional
mean and standard deviations.
Both the median and interquartile ranges are based on order statistics. They are derived by
ordering data values from high to low. The median is simply the middle value of the data set. The
interquartile range is the difference between the value at the 75 percent level and the value at the
25 percent level.
The Box Plot
The box plot is a convenient method of presenting lake data based on the robust order statistics.
In one simple graphic, the box plot can provide information on:
• the median,
• data variability around the median,
• data skew,
• data range, and
• the size of the data set.
A box plot is constructed using the following steps:
1. Order the data from lowest to highest.
2. Plot the lowest and highest values on the graph as short horizontal lines. These are the
extreme values of the data set and repre sent the data range.
3. Determine the 75 percent value and 25 percent value of the data set. These values define
the interquartile range and are represented by the location of the top and bottom lines of
the box.
4. The horizontal length of the lines that define the top and bottom lines of the box (the box
width) can be used as a relative indica tion of the size of the data set. For example, the box
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width that describes a lake data set of 20 values can be displayed twice as wide as a lake
with a data set of 10 values. Alternatively, the width may be set as proportional to the
square root of the sample size. Any proportional scheme can be used as long as it is
consistently applied.
5. Close the box by drawing vertical lines that connect to the ends of the horizontal lines.
6. Plot the median as a dashed line in the box.
8.B Algae Results
The information in this section will be presented by using a data set from a fictitious lake
appropriately named Volunteer Lake.
Volunteer Lake was sampled on the 1st and 15th of the month from May 15 to October 15. The
lake depth at the sampling station was 30 feet. At one sampling site over the deepest part of the
lake, volunteers:
• measured Secchi disk transparency,
• took a chlorophyll a sample at a depth of 3 feet, and
• took total phosphorus samples at depths of 3 feet and 26 feet.
Secchi Disk Transparency
Secchi disk transparency is a parameter that interests volunteers. Data are easily understandable
and can be presented by a modified bar graph. The horizontal axis presents the sampling dates
and the vertical axis represents the lake's water column.
Miniature Secchi disks extend down from the surface to the actual Secchi disk reading.
General trends in Secchi disk measurements can be noted in this data presentation, but the
graphic emphasis is on the individual reading on each sampling date.
Chlorophyll a
Chlorophyll a is usually best presented in a traditional bar graph. By examining this data
presentation, volunteers can observe when chloro phyll a concentrations were high and low
during the sampling season.
The horizontal axis presents the sampling dates. The vertical axis is a scale of chlorophyll a
values. Like the Secchi disk graph, general trends can be noted, but the graphic emphasis is on
the chlorophyll a concentration on each sampling date.
Total Phosphorus
The total phosphorus graph displays the surface and bottom data together. By examining this
double bar graph, volunteers can observe when phosphorus concentrations were high and low in
each zone. In addition, they can compare surface and bottom concentrations on each sampling
date.
The horizontal axis presents the sampling dates. The vertical axis is a scale of total phosphorus
values. As with the other bar graphs, general trends in measurements can be noted, but the
graphic emphasis is on phos phorus concentrations measured on each sampling date.
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Data Interpretation
In addition to displaying graphs, box plots, and summary statistics, the report author must provide
interpretation of what the data presentations mean. The interpretation process begins with a data
analysis by an experienced limnologist. The report author then has the critical job of putting
technical analysis into terms that can be understood by volunteers. Toward this end, data
interpretation is often best presented in the context of an explanation of how the lake functions
during a seasonal cycle.
Although time-consuming, a thoughtful explanation by the report author rewards volunteers with
greater insight and understanding of their lake.
Examples of observations and reasonable conclusions based on the data from Volunteer Lake
may include the following:
• Secchi disk readings were highest in May and October, and lowest in September.
• Chlorophyll a concentrations were relatively low from May through July. After July 15,
concentrations increased, reach ing a maximum concentration on September 15.
• Phosphorus concentrations at a depth of 3 feet were generally moderate in May and
October and relatively low in the summer. Phosphorus concentrations near the lake bottom
were generally moderate in May, June, and October. Concentrations increased during the
summer, reaching a maximum on September 1.
• The algal population can affect water clarity during the summer and early fall. This is
evidenced by the fact that Secchi disk readings and chlorophyll a concentration followed
opposite paths. When one was high, the other was low. Notably, the lowest Secchi disk
reading occurred on the same date as the highest chlorophyll a concentration (September
15).
The reduction of water transparency on June 15 may be due to algae, but it may also be due
to increased water turbidity from a spring rain. A check of the field data sheet can often
explain sudden variations in data magnitude.
• Algae take up and then remove phosphorus from the surface waters as they die and sink to
the lake bottom. This is evidenced by lowered phosphorus concentrations during the
summer.
• The lake probably stratifies into a warmer upper layer (epilimnion) and a colder lower layer
(hypolimnion). Also, the lower layer probably is also anoxic in the summer. This theory is
supported by the large concentration of phosphorus found in the lower layer during those
months. The likely source of this phosphorus is lake bottom sediments that leach
phosphorus to the overlying waters under anoxic conditions.
• In all likelihood, Volunteer Lake experiences a spring and fall overturn. This is evidenced by
nearly equal shallow and deep total phosphorus concentrations on May 15 (spring
overturn), October 1, and again on October 15 (fall overturn). The nearly equal
concentrations indicate that the lake is mixing vertically and distributing phosphorus evenly
throughout the water column.
• There may be a problem with fall algal blooms, which will reduce water clarity. Fall overturn
may be stimulating increased growth when it brings phosphorus (released from the
sediments during anoxic conditions) to the surface waters. Algae often reproduce rapidly
when given this new pulse of nutrients.
Trophic State
Secchi disk transparency, chlorophyll a, and total phosphorus are often used to define the degree
of eutrophication, or trophic status of a lake. The concept of trophic status is based on the fact
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that changes in nutrient levels (measured by total phosphorus) causes changes in algal biomass
(measured by chlorophyll a) which in turn causes changes in lake clarity (measured by Secchi
disk transparency).
A trophic state index is a convenient way to quantify this relationship. One popular index was
developed by Dr. Robert Carlson of Kent State University. His index uses a log transformation of
Secchi disk values as a measure of algal biomass on a scale from 0-110.
Each increase often units on the scale represents a doubling of algal biomass. Because
chlorophyll a and total phosphorus are usually closely correlated to Secchi disk measurements,
these parameters can also be assigned trophic state index values.
The Carlson trophic state index is useful for comparing lakes within a region and for assessing
changes in trophic status over time. Thus it is often valuable to include an analysis of trophic state
index values in summary reports of a volunteer monitoring program.
The program manager must be aware, however, that the Carlson trophic state index was
developed for use with lakes that have few rooted aquatic plants and little non-algal turbidity. Use
of the index with lakes that do not have these characteristics is not appropriate.
TSI = 60 -14.41 In Secchi disk (meters) TSI = 9.81 In Chlorophyll a (ug/L) + 30.6
TSI = 14.42 In Total phosphorus (ug/L) + 4.15
where:
TSI = Carlson trophic state index
In = natural logarithm
The formulas for calculating the Carlson trophic state index values for Secchi disk, chlorophyll a,
and total phosphorus are presented below. Also presented is a table that lists the trophic state
values and the corre spending measurements of the three parameters.
Ranges of trophic state index values are often grouped into trophic state classifications. The
range between 40 and 50 is usually associated with mesotrophy (moderate productivity). Index
values greater than 50 are associated with eutrophy (high productivity). Values less than 40 are
associated with oligotrophy (low productivity).
Presented below are Carlson trophic state index values for Volun teer Lake. Summer averages
(June 15 - September 1) are used in the calcula tions. As seen from the TSI values, Volunteer
Lake can be classified somewhere near the border of mesotrophy and eutrophy.
Secchi Disk
Average Summer Secchi disk = 5.9 feet = 1.8 meters
TSI = 60 -14.41 (In Secchi disk (meters))
TSI =60-(14.41) (0.59)
TSI = 51.5
Total Phosphorus
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Average Summer Surface Total Phosphorus = 19.6 ug/L
TSI = 14.42 (In Total phosphorus (ug/L)) + 4.15
TSI = (14.42) (2.98) = 4.15
TSI = 47.1
Chlorophyll aAverage Summer Chlorophyll a = 17.2 ug/L
TSI = (9.81) (In Chlorophyll a (ug/L)) + 30.6
TSI = (9.81) (2.84)+ 30.6
TSI = 58.5
8.C Aquatic Plant Results
Chapter 4 describes three activities that volunteers can use to monitor the rooted aquatic plant
condition:
• mapping the distribution of plants at or near the surface;
• estimating percent composition and relative density of plant types at stations located along
a transect line that runs perpendicular from shore; and
• collecting plant types for professional identification.
Reporting the results of these activities can be relatively straightforward. The rough aquatic
plant map drawn by volunteers can be cleaned -up and reproduced (see below).
Estimates of the percent composition of the different plant types at each transect station are
best displayed by using a pie graph. Relative density information can also be incorporated
into the graph. Identified plants can be listed along with a sketch and a short description.
8.D Dissolved Oxygen Results
As in Section 8.B, this information will be presented using fictitous data set from Volunteer Lake.
Temperature and oxygen profiles were measured at one sampling site located over the deepest
part of the lake on April 15 and July 15. Using a temperature/oxygen meter, volunteers recorded
readings at five-foot intervals from the surface to the lake bottom. A data table of the results is
presented below.
Results of the temperature and dissolved oxygen measurements (profiles) can be presented
together on the same line graph (page 117). The horizontal axis displays a range of values that
can be read both as dis solved oxygen units (mg/L) and temperature units (°C). The vertical axis
represents the water column of the lake with the surface at the graph's top and the lake bottom at
the graph's bottom.
References
Carlson, R.E. 1977. A Trophic State Index for Lakes. Limnol. Oceanogr. 22:363-369.
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Cooke, G.D., Welch, E.B., Peterson, S.A. and Newroth, P.R. 1986. Lake and Reservoir
Restoration. Butterworth Publ. Stoneham, MA.
State of Michigan Dept. of Natural Resources. December, 1987. Common Aquatic Plants of
Michigan. Land Water Mgt. Div., Lansing, Ml.
New York State Dept. of Environmental Conservation and Federation of Lake Associations, Inc.
1990. Diet fora Small Lake: A New Yorker's Guide to Lake Management. Albany.
Reckhow, K.H. and S.C. Chapra. 1983. Engineering Approaches for Lake Management. Vol 1 Data
Analysis of Empirical Methods . Butterworth Publ. Woburn, MA.
U.S. Environmental Protection Agency. August 1990. Volunteer Water Monitoring: A Guide for
State Managers . EPA 440/4-90-010. Off. Water, Washington, DC.
Appendix: Scientific Supply Houses
A partial list of chemical and scientific equipment companies that supply volun teer lake
monitoring programs
Chestertown, MD21620
Millipore Corporation
Technical Services
800-225-1380
Thomas Scientific
Main Office
609-467-2000
VWR Scientific
P.O. Box 2643
Irving, TX 75061
800-527-1576
Wildlife Supply Company
301 Cass Street
Saginaw, Ml 48602
517-799-8100
YSI Incorporated
1725 Brannum Lane
Yellow Springs, Ohio 45387
Cost ranges for some typical monitoring equipment: Secchi disc $20-$40
Water Samplers $100 - $400
Dissolved Oxygen Meter $500-$1,000
Dissolved Oxygen Sampling Kit $40 - $60
pH Meter $300 - $500
pH Test Kit $40 - $60
Alkalinity Test Kit $20 - $50
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Phosphate Test Kit $100 - $400
Fisher Scientific
711 Forbes Ave.
Pittsburgh, PA 152
9800-225-4040
HACH Company
P.O. Box 389
Loveland, CO 80539
800-525-5940
Hydrolab Corporation
P.O. Box 50116
Austin, TX 78763
512-255-804
LaMotte Chemical Products Inc.
P.O. Box 329
Office of Wetlands. Oceans & Watersheds Home
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