Developing a Lake
Management Plan
Prepared by the Interagency
Lakes Coordinating Committee
Contributing agencies:
Minnesota Board of Water and Soil Resources
Minnesota Department of Natural Resources
Minnesota Pollution Control Agency
Minnesota Department of Agriculture
With participation by
Minnesota Lakes Association
Metropolitan Council
Hennepin Parks
August 1996
2
Foreward
Thank you for wanting to know how to better
manage your lake. Lake management must
be a collaborative process involving all
interested parties —along with quite a few
technical specialists— to be successful. This
publication is designed to help you be
successful in your lake management efforts.
“Developing a Lake Management Plan” is a
companion document to the Minnesota Lake
and Watershed Data Collection Manual,
published by Minnesota’s Environmental
Quality Board Lakes Task Force. The goal of
“Developing a Lake Management Plan” is to
help you develop a lake management plan
that has specified goals for local, county and
state governmental units and organizations. It
is likely that the lake management plan will
become a critical tool in focusing limited
public attention and resources for your lake.
Since every lake management plan demands
good data on which to base sound decisions,
the Data Collection Manual should be read
first. Data collection should be well under
way before attempting to prepare a lake
management plan.
We also would appreciate your comments
and suggestions on how to improve this
manual, or any lake-related management
services. Your input is very important to us.
Please address your comments to: Chair,
Minnesota Interagency Lakes Coordinating
Committee, and send to any of the following:
Commissioner, Minnesota Department of
Natural Resources
500 Lafayette Road
St. Paul MN 55155
Commissioner, Minnesota Pollution Control
Agency
520 Lafayette Road.
St. Paul MN 55155
Executive Director, Minnesota Board of
Water and Soil Resources
One West Water Street, Suite 200
St. Paul MN 55107
Commissioner, Minnesota Department of
Agriculture
90 West Plato Boulevard
St. Paul MN 55107
Chair, Metropolitan Council
230 East 5th Street
St. Paul MN 55101
For additional copies, contact the Minnesota Board of Water and Soil Resources, One West Water
Street, Suite 200, Saint Paul, MN 55107 (612) 296-3767.
The Interagency Lakes Coordinating Committee
(ILCC) has guided the work on this manual. The
ILCC was formed by a memorandum of agreement
between the Minnesota Department of
Natural Resources (MDNR), the Minnesota
Pollution Control Agency (MPCA), the Minnesota
Board of Water and Soil Resources (BWSR), the
Minnesota Department of Agriculture (MDA) and
the Metropolitan Council (Met Council) in 1993
to improve the coordination of lake management
and planning activities of these agencies. The
Minnesota Lakes Association (MLA) has also
been an active ad hoc participant in the ILCC.
The ILCC formed committees to work on both the
Lake and Watershed Data Collection Manual and
this planning manual. In October 1994, the EQB
Lakes Task Force merged with the ILCC and is
continuing to implement the recommendations of
the Lake Management Forum (started in 1991).
This document represents a collaborative effort
among the aforementioned parties and does not
necessarily reflect the policies of the individual
agencies or divisions within an agency.
The committee is grateful to all the agency staff,
local units of government staff and lake association
members whose encouragements, hard work
and support contributed to this project. The BWSR
deserves special acknowledgment for their work
editing and printing the document. We are hopeful
that such teamwork will continue as lake management
planning moves forward to protect and
enhance the qualities of Minnesota lakes.
The Minnesota Interagency Lakes
Coordinating Committee
August 1996
3
Table of contents
I. Introduction …………………………………………………………………………………… 4
II. Planning: A model framework for lake management plans………………. 5
A. Getting Started ……………………………………………………………………………………………..5
1. Form an advisory group.
2. Appoint a citizen steering committee
3. Assemble a technical committee
4. Educate the steering committee
B. Gather Information……………………………………………………………………………………… 7
1. Physical and biological characteristics
2. Land use characteristics
3. Social/demographic trends
C. Identify and set priorities …………………………………………………………………………….. 7
D. Develop goals, objectives and actions …………………………………………………………… 8
E. Implementing and monitoring progress …………………………………………………………. 8
III. Overview: Factors influencing lake management ……………………………. 9
A. Regional patterns………………………………………………………………………………………… 9
B. The lake-watershed connection……………………………………………………………………..10
1. Watershed size
2. Watershed hydrology
3. Precipitation
4. Soils
5. Land use
C. Lake water quality monitoring and assessment ……………………………………………….12
1. Common sampling procedures
2. Common stream sampling procedures
3. Fish community structure as an indicator of water quality
IV. Lake Management Focus Areas …………………………………………………….. 14
A. Water Quality ……………………………………………………………………………………………..14
B. Fisheries management plans …………………………………………………………………………15
C. Aquatic vegetation ………………………………………………………………………………………16
D. Wildlife ……………………………………………………………………………………………………..18
E. Exotic species ……………………………………………………………………………………………..19
F. Land use and zoning ……………………………………………………………………………………21
G. Managing water surface use conflicts …………………………………………………………….22
H. Public water access ……………………………………………………………………………………..24
V. Conclusion…………………………………………………………………………………. 25
VI. References …………………………………………………………………………………. 25
Appendixes – (not avaible with PDF – out of date)
Appendix A – Water quality indices
Carlson Trophic Index
Fish Community Structure Graphs
Appendix B – Lake water quality benchmarks based on ecoregion
4
I. Introduction
Water… Lakes… Fishing… Swimming…
Canoeing… Cabins…. these words bring to
mind the fundamental Minnesota experience.
We take the abundance and diversity of our
lakes, rivers and wetlands for granted.—and
with good reason: Minnesota has more than
15,000 lakes that are 10 acres or larger. More
than 5,000, covering more than three million
acres, are actively managed for their fisheries.
Many others are used for boating,
waterskiing, hunting and swimming, and just
plain appreciated for their beauty.
The excitement of the walleye opener, a
week-long vacation at the cabin, the solitude
in the Boundary Waters Canoe Area, or the
relaxation from a walk around a lake in a city
park all speak to the special relationship
Minnesotans have with lakes. Thanks to
them, travel and tourism is our second largest
industry. With 208,000 miles of shoreline,
Minnesota offers more waterfronts than the
states of California, Florida and Hawaii
combined!
In 1986, the 28 million visitors who traveled
to and through the state generated nearly $7
billion in revenues. About 73 percent were
vacationers, with outdoor activities rated
high on their lists of preferred activities.
Keeping our lakes clean directly relates to
Minnesotans’ ability to compete with regional
lake centers such as northern Wisconsin,
Ontario and Michigan for these related
industries and income sources, which in turn
contribute to local schools, roads, health
programs, social services and law enforcement
services and infrastructures.
Lakes cannot manage themselves.
In order to maintain these beneficial uses,
lakes need help. With ever increasing recreational
use and growing populations residing
near and along waterways, lakes can suffer
from small and large cumulative impacts and
cannot manage themselves. We affect our
lake by our actions within the lake, along its
shorelines and well up into the lake’s watershed
or drainage basin. Even distant areas can
be connected to the lake by the downstream
flow of waters which, in turn, carry pollutants,
sediments and nutrients into the lake
over time. We all are part of the problem, but
we all can do something, no matter how
apparently insignificant (e.g., recycling of
household materials), to help our lakes. Lakes
need to be systematically and purposefully
managed over time if we are to sustain their
long-term health and viability.
5
A. Getting Started
Appoint a citizen steering
committee.
The job of the steering committee is to define
the citizen advisory group’s concerns, to
educate themselves and the larger community
on the sources and dimensions
of the concerns, and to
identify, study and recommend
possible solutions. The
work of the steering committee
must be fair, objective
and impartial for it to be
accepted and put into action
by the larger community.
The size of the steering committee may vary,
but it needs to be workable. Include representatives
appointed from local and county
governments. Designate a chairperson who is
well respected by diverse groups and able to
forge partnerships. The committee should
choose when and where it will meet. It is a
good idea to set target completion dates for
committee work so that there is a defined
time commitment for members. In addition, a
separate technical committee may be established
to advise the steering committee.
Form an advisory group.
Identify the parties interested in the management
of the lake and the lake’s watershed.
Invite all legitimate groups
with an interest in the lake
resource to participate in a
citizen advisory group. It is
particularly important to
include people or organizations
that may not believe
there is a need to develop a
lake management plan.
While it may make initial contacts or meetings
more difficult, considering all sides will
lead to better solutions and implementation.
Excluding some interests and viewpoints may
lead to a future sabotage of the plan and can
keep good resources or ideas away.
II. Planning: a model framework for lake
management plans
tion of a citizen steering committee that
organizes a lake management planning
advisory group, with membership from all
legitimate lake and watershed groups.
Lake management planning must include
members representing diverse interests and
perspectives to reduce the risk of failing. The
activities of the citizen steering committee
require that its members have the time to
dedicate to make the effort successful; many
groups have formal rules of attendance for
voting and participation.
The typical lake management steering committee
member may need to dedicate one to
three years (or more) toward the effort.
Attending meetings once or twice a month is
an important aspect of being a steering
committee member.
Lake management plans help protect natural
resource systems, including the water quality
of the lake and the associated fish, vegetative
and wildlife communities. A lake management
plan:
Encourages partnerships between concerned
citizens, including lakeshore
owners, watershed residents, resource
management agencies and special interest
groups.
Identifies the concerns that the people feel
are important to address.
Sets realistic goals, objectives and actions.
Identifies needed funds and personnel.
The planning process starts with the forma-
Citizen
steering
committee
Advisory
group
Developing a Lake Management Plan
6
Assemble a technical committee.
Formally request assistance from local,
regional, state and federal governmental
groups to appoint staff to a technical committee.
The technical committee will advise and
assist the steering committee on all technical
issues.
Suggested contacts for
technical assistance
State Agencies such as
MPCA and MDNR regularly
collect information on water
quality, fish populations and
other natural resources.
Contact your area or regional
office.
Local Units of Government (LGUs) including
counties, soil and water conservation
districts and watershed districts, may also
collect land and watershed information and
have land use, ownership and tax information.
Local lake associations and volunteers.
Federal Agencies such as the Natural Resources
Conservation Service (NRCS).
Private consulting services and commercial
enterprises.
Educate the steering committee.
Effective planning starts with an understanding
of the technical, social, economic and
demographic factors influencing a lake.
Understanding the historical and current
conditions, along with
projected future conditions,
will also help establish
effective goals and objectives
and identify the
appropriate actions to
address the interest group’s
concerns.
Review all pertinent resource
plans before beginning to develop a
lake management plan. These plans will
provide some of the data needed, andy may
identify goals, objectives and actions appropriate
for the lake. Resource plans include,
but are not limited to,
local land use plans (zoning controls);
comprehensive local water management
plan;
lake assessment studies;
MDNR fisheries management plans;
watershed district plans; and
soil and water conservation district
comprehensive plans.
(Please refer to appendix A for information
on how to contact local County Water
Planners, DNR Area Fisheries and Area
Wildlife Offices, and MPCA state and regional
offices.)
Plan on the education phase extending over a
six- to 12-month period. Mandatory attendance
at the educational meetings is necessary
in order to effectively identify the
challenges and opportunities to be addressed
by a lake management plan.
Technical
committee
Successful Steering Committees
Focus on the concerns identified,
rather than assigning blame.
Resolve from the beginning to work
toward common goals and understanding.
Are willing to set aside differences
while working on areas where
solutions seem possible.
Treat all members of the committee
with respect.
Recognize that resource damage of
the past and present are often
unintentional, and often result from
lack of knowledge or information.
Work for consensus, so that everyone
will be committed to the actions
proposed.
Make field trips and site visits to
clarify problems and solutions and
increase team cohesion.
Focus on specific, constructive actions
that work, not on global environmental
problems.
Know that nothing inspires people
like success— they get a few decisions
made as soon as possible.
Have some fun—and appreciate the
contributions of all involved in a
tangible way.
Education
7
B. Gather Information
Lake management planning entails gathering
data about the lake and the watershed,
including the physical features, land use and
social trends. Please refer to The Minnesota
Lake and Watershed Data Collection Manual
for specific instructions on gathering information.
Important data typically includes:
1. Physical, chemical and biological
characteristics
a. Delineate the watershed boundary.
Calculate the watershed to lake surface area.
b. Identify the watercourses within the
watershed. Include streams, drainage ditches,
tile lines and city storm water or sewer lines
that drain into and out of the lake.
c. Identify the soil types and slopes within
the watershed.
d. Identify the lake size, depth, bottom
contours, structures and surrounding groundwater
levels.
e. Identify fish populations.
f. Identify the aquatic vegetation.
g. Identify exotic plant species within the
watershed.
h. Identify endangered, threatened or rare
plants, animals or natural communities (see
Reference Section–Other for information on
requesting data from the Minnesota Department
of Natural Resources).
2. Land use characteristics
a. Historical: Determine the presettlement
drainage patterns, wetlands and vegetation.
b. Current: Identify areas where presettlement
conditions still exist. Identify
agricultural lands, urban and residential lands
and recreation lands, and any other pertinent
uses.
c. Future: It is important to plan for activities
that are likely to develop in the future.
3. Social and demographic trends
Look at the economic activities taking place
within the watershed and consider how they
can be sustained, or even improved, with
successful lake and watershed management.
Also learn about the attitudes of people living
in (or using the resources of) the lake’s
watershed. Do the majority perceive a
resource problem? What is the present and
projected population of the watershed, and
where is it concentrated?
C. Identify concerns, set
priorities.
Most efforts to improve the quality of a lake
begin with an identified concern or problem.
These concerns must be articulated as clearly
as possible to motivate citizens to take the
actions needed.
Have the advisory group members identify
and list all concerns regarding the watershed’s
natural resources and economic trends that
have an impact on quality or use.
Following are examples of concerns that can
be identified through a survey. The number in
the parenthesis indicates how often the
concern was identified by the 108 stakeholders
surveyed:
Fish harvest has been declining over the last
decade (42).
The lake is frequently covered with scum (32).
The watershed is contributing large amounts
of nutrients and sediment to the lake (24).
Private septic systems are a problem (20).
Jet skis are ruining the lake (17).
Farmers in the watershed must be able to
make a living (12).
Have the advisory group members assess and
prioritize the concerns. Use criteria such as:
Is the group able to change the situation?
Is the group motivated enough to address the
concerns?
Will the costs outweigh the benefits?
Use the inventory information
to determine the critical
areas in need of management.
Target the management
efforts to the areas
that will benefit the most
and where the group’s input
will make the biggest
difference.
After the concerns have
been identified and prioritized,
develop a vision
statement.
Sample vision statement:
The natural watershed process
and functions are being
restored to reduce nutrient
and sediment loads delivered
to Great Lake by at least 60
percent. The health and
quantity of aquatic plant
community in the lake are
good and getting better and
covers 75 percent of the lake
shoreline. The lake is attracting
anglers and other water
recreational activities.
Developing a Lake Management Plan
8
D. Develop goals,
objectives and actions
Once the problems are identified and prioritized,
set goals and objectives to address the
high priority problems. Finally, identify
actions to achieve the goals and objectives.
Staff and budget constraints may affect the
number of goals established for the lake
management plan.
1. Establish goals, objectives and
actions.
a. Goals are general statements relating to
what the group hopes to accomplish over the
long term. They are achievable.
Examples: Protect and improve the water
quality of Great Lake by reducing the
nonpoint pollution entering the lake from the
watershed.
Reduce in-lake phosphorous concentrations.
b. Objectives convey what the group
hopes to accomplish in the near term to make
progress toward the goal. They are specific
and measurable.
Examples: By the year 2000, nutrient and
sedimentation delivery rates to Great Lake
will be reduced by 40 to 60 percent from
current levels.
By the year 2004, the in-lake phosphorous
level will be reduced to 30μg/ (+/- 10μg/l.)
c. Actions are the specific steps that will
be taken to accomplish the objective. They are
realistic and results-oriented.
Examples:
1. Identify land parcels in the watershed
where the estimated erosion rate annually
exceeds twice the tolerable soil loss limit (T).
2. Identify land parcels adjacent to streams
and tributaries where erosion exceeds the
tolerable soil 2. loss limit.
3. Identify the owners of the parcels identified
in actions 1 and 2.
4. Develop farm management plans on 80
percent of the acres identified in action 1.
5. Implement best management practices (for
water quality) to control erosion within T on
75 percent of the acres planned.
6. Retire 75 percent of the acres identified in
actions 1 and 2 from row-crop production.
7. Develop grazing management plans for all
acres identified in actions 1 and 2 that are
being pastured or will be converted to pasture
land.
8. Identify steep slopes and bluffs and any
known erosion problems.
9. Identify areas unsuitable for development
and work with the county planning and zoning
office to restrict development of these areas.
10. Inventory existing septic systems on
shoreland property.
11. Identify existing shoreland development by
types (e.g., permanent residence, seasonal
residence, business, etc . . . ).
E. Implementing and
monitoring progress
Prioritize actions based on the likelihood that
they can be accomplished within the specified
timeframe, and their importance in
achieving identified objectives.
Identify who is responsible for coordinating
and completing each action. Include the
timeframe for completion and the estimated
cost for the action.
Seek and secure required funds.
Determine appropriate measurements to use
to monitor progress.
Report progress that has been made to the
interested parties identified in section I of this
outline.
Frequently review and update the lake
management plan.
9
III. Overview: factors influencing lake
management
Western Corn Belt Plains
A. Regional patterns
Minnesota brings to mind pristine lakes
inhabited by loons, bountiful populations of
walleyes and canoe-traveling visitors, but
this picture does not reflect the natural
variability of lakes found across the state.
They range from the cold, deep waters of the
northern boreal forest to the warm, shallow
lakes of the southwest prairies. The northeast
region’s rocky landscape, nutrient-poor soils,
forest cover and frequent rainfall have
resulted in lakes with clear water, while the
lakes of southern Minnesota have evolved in
nutrient-rich soils. These southern lakes
receive considerably less rainfall than their
northern counterparts and are often murky.
Recognition of regional patterns and limitations
helps put the characteristics and conditions
in a particular lake and watershed into
perspective. More than 30 years of monitoring
by state agencies and citizen volunteers
gives us a good understanding of the regional
patterns in Minnesota’s lake water quality.
Seven ecoregions have been identified in the
state based upon land use, soils, geology and
natural vegetation patterns. Four of the seven
ecoregions include 98 percent of the state’s
lakes (see below: Northern Lakes and Forests
(NLF); North Central Hardwood Forests
(NCHF); Northern Glaciated Plains (NGP)
and the Western Corn Belt Plains (WCBP).
Minnesota’s ecoregions
Northern
Glaciated
Plains
10
Developing a Lake Management Plan
Table 1: Land use patterns by ecoregion. Percent of 40 acre parcels with land use characteristics.
Based on 1968-1969 land use data from the State Planning Information Center.
Land Use %NLF %NCHF %WCBP %NGP
Cultivated 4.6 49.3 82.9 83.7
Forested 75.2 15.9 3.5 0.7
Water and Marsh 10.6 8.1 1.7 2.9
Pasture and Open 7.3 21.4 10.0 11.4
Developed 1.9 5.2 1.8 1.2
Developed by Heiskary and Wilson (1989; 1990)
Soils, geology, land cover, the intensity of
land use and other factors determine the
amount of sediments and nutrients lost in
runoff waters per acre of land. Forested and
wetland areas generally retain sediments and
nutrients quite well. In contrast, urban and
agricultural areas can have the greatest loss
rates unless reasonable corrective measures
are established. Looking at broad ecoregion
areas, the loss rate of phosphorous varies
from about 0.1 kilogram phosphorus per
hectare per year (or about 0.1 pounds per
acre per year) in the NLF to about 0.8
kilogram per hectare per year (or about 0.7
per acre per year) in the WCBP. The impact
of these loss rates on a lake can be considerable,
as one pound of phosphorous can
generate up to 300 or more pounds of aquatic
plants within the lake basin. Excessive plant
and algae growths (the small microscopic
plants that can color water green) are generally
a primary focus of lake user complaints
and concerns.
B. The lake-watershed
connection
Lakes are simply depressions in the landscape
that are continually filled with water
from melting snow or rainfall and groundwater.
These depressions were created through
glaciation from the last ice-age.
The water quality of a lake depends largely
on the conditions and dynamics of the
watershed. Every watershed is unique and
several factors interact to define a lake
basin’s characteristics.
Watershed Size
In the simplest terms a watershed can be
defined as the area of land that drains into a
lake or river. One of the very first steps in
lake management planning is to understand
the relative size and characteristics of the
watershed. The Minnesota Lake and Watershed
Data Collection Manual provides
information on watershed delineation.
The following terminology is often used
when describing various watershed management
units:
Watershed size range
Mgmt Unit (approx.)
Catchment 0.5 – 1 sq. mi.
Sub-watershed 1 – 10 sq. mi.
Watershed 10 – 100 sq. mi.
Sub-basin 100 – 1,000 sq.mi.
Basin 1,000 – 10,000 sq. mi.
Most local watershed planning is done at the
sub-watershed and watershed level.
Watershed hydrology
The hydrology of a watershed is defined as
the route the precipitation takes on its way to
the lake. Some precipitation will fall directly
on the lake surface, some will runoff the
adjacent land surface into the lake and some
infiltrates into the land surface recharging the
groundwater. As water flows over the surface
of the land or beneath the ground it can pick
up nutrients, minerals and organic matter and
deliver them to the lake where they will
influence the lake’s characteristics. A basic
understanding of the watershed’s hydrology
is important to lake management because
modifications in the watershed, such as
farming, development, draining of wetlands
and the loss of forests can increase how much
and how fast water reaches the lake. Increases
in either the rate or quantity of
surface water runoff can escalate the transport
and delivery of sediment and attached
nutrients to the lake, and can increase flooding
and erosion of streambanks along watercourses
flowing to the lake.
11
capacity. The tannic acid produced by some
organic soils can make the water appear
brown or stained.
A basic understanding of soils helps target
watershed protection programs to sites that
will maximize available resources. For
example, if there are two subwatersheds of
similar size, it may be wise to target soil
erosion control practices to the one with a
high percentage of silt and clay, because
these soils will have a higher potential to
negatively impact the lake.
Landscape Features
Features on the landscape, both natural and
resulting from human activity, greatly influence
the characteristics of a lake. Converting
land from its natural vegetation state (prairie,
wetlands or forest) to cropland or urban uses
almost always increases surface water runoff.
Surface runoff from cropland and urban land
often has nutrients (such as phosphorous) and
toxins (such as pesticides) attached to the
sediment. If natural filters such as wetlands
are not present on the landscape, the sediment
and pollutants can be transported to the lake.
The concentration of the nutrients from
fertilizer on cropland or urban land depends
on many factors, including the application
method, the time of application in relation to
rainfall and the solubility of the nutrients.
Animal feedlots, pastures and home septic
systems can also add nutrients to the lake.
The sediment itself can degrade fish habitat
and threaten plantlife.
Lakes that are hydrologically connected to
other lakes and large open-water wetlands
often have unique characteristics that must be
acknowledged when developing a lake
management plan. For instance, if water
entering a lake has flowed through other
water bodies, the land use practices and inlake
water chemistry in the upstream lake(s)
or wetland(s) will affect the target lake.
Modifications to the natural hydrology, such
as the construction of ditches and storm
sewers, can significantly alter the rate and
quantity of surface water runoff. If either the
rate, quantity or quality of surface water
runoff from a lake’s contributing watershed is
determined to be a problem, understanding
the watershed hydrology will be the first step
in identifying appropriate goals and objectives
in the lake management plan.
Many factors influence watershed hydrology,
including the physical characteristics described
below—precipitation, soils and the
use of the land. Layers of sand, gravel and
clay deposited by glaciers created the groundwater
flow patterns that affect lakes. Depending
on the patterns and the climate, a lake
may either receive water from or discharge
water into the groundwater system.
Precipitation
The frequency, intensity and time of year that
rainfall or snowmelt events normally occur
within a watershed will influence the lake.
Precipitation has the ability to detach soil
particles (sediment) and transport them to a
receiving water body.
The potential for precipitation to cause soil
erosion and to transport pollutants to a lake
depends on the land use, and on rainfall—
when, how much and how intense it is.
Precipitation is very different, depending on
where you are in Minnesota. Total precipitation
varies from a low of 20 inches/year in
northwestern Minnesota to a high of 32
inches/year in southeastern Minnesota. The
average annual surface runoff is greatest in
southern and southeastern Minnesota and the
lowest in northwest and west-central Minnesota
along the border with the Dakotas.
Generally, the potential for raindrops to
erode soil and transport the sediment and
attached pollutants to a lake is greater in
southern and eastern Minnesota than in
northern and western Minnesota.
Soils
Understanding soil types found in the watershed
is important, because they influence
surface water runoff, both how much gets to
the lake, and its quality. Soils in Minnesota
fall into two broad groups: mineral and
organic. Mineral soils are made up of varying
ratios of sand, silt and clay particles. Soils
made primarily of sand absorb precipitation
quickly and are naturally low in available
phosphorus and nitrogen. In contrast, soils
made of primarily silt and clay generally have
lower absorption rates and are generally high
in available phosphorus and nitrogen.
Organic soils are made up of more than 50
percent organic materials, such as peat.
Generally, they are not subject to erosion by
water because of their position in the landscape
(swales) and their high water holding
12
Developing a Lake Management Plan
C. Lake water quality
monitoring and
assessment
Measuring the lake’s chemical, biological and
physical composition is essential to understanding
how the lake works and to identifying
appropriate lake management options.
Initial measurements will establish parameters
that can characterize the trophic* status and
overall ecology of the lake.
The Minnesota Lake and Watershed Data
Collection Manual provides detailed information
on what needs to be collected, along with
how to collect it.
1. Common lake sampling
procedures
A good way to gather lake water quality data
is to sample surface water parameters on five
to 10 occasions from May to September.
Collect samples at one or more preselected
mid-lake locations. Lakes with distinct bays
need more sampling sites than round ones.
Given the considerable differences in summer
weather dry to wet patterns, it will take a
minimum of three to five years of data
collection to be able to statistically define
“average” conditions.
The parameters most often used to describe
the trophic status of a lake are total phosphorus,
Secchi transparency and chlorophyll-a.
Since concentrations of total phosphorus and
chlorophyll-a are usually expressed in partsper-
billion ranges (μg/L), analytical labs must
be equipped to accurately measure these
extremely small concentrations.
As land uses vary by ecoregion, so do lake
water quality patterns (table 2). There are
distinct differences in water quality between
ecoregions. Average regional concentrations
of total lake phosphorus vary from 24 μg/L in
the Northern Lakes and Forests ecoregion to
more than 100 μg/L in the Western Corn Belt
Plains and the Northern Glaciated Plains
ecoregions. Ranges in algae (chlorophyll-a)
and transparency followed the same pattern.
2. Common stream sampling
procedures
Since lake water quality depends on the
volume and quality of the waters it receives
from its watershed, inflowing streams must
also be sampled. Usual time periods are
sometime in March through November. The
point is to gauge stream flows with either a
staff gauge, a metal yard stick or a continuous
recording device such as a small computer
(these cost about $1,500 to $2,500 per
installation). Streams are then sampled by
hand, called “grab samples,” or by sophisticated
automated samplers that require professional
installation and cost $3,000 or more.
Generally, smaller watersheds need to rely
more on automated sampling, because
surface water runoff tends to peak quickly
and is of very short duration. Typically, at
least 15 total phosphorus measurements per
station per year are needed to reasonably
define phosphorus concentrations along with
a continuous record of daily average flows.
Other core parameters needed include total
suspended solids and total nitrogen. Analytical
laboratories must be able to accurately
detected low concentrations of these parameters.
Similar to lakes, distinct differences in
average concentrations have been noted by
ecoregion for streams. Average regional
concentrations of total phosphorus varied
* “Trophic status” refers to the nutrients in the
lake—what kind and how much.
Table 2: Summer mean lake water quality measures by ecoregion with interquartile in the parenthesis
(i.e., 25th and 75th percentile)
Factor Considered NLF NCHF WCBP NGP
Total Phosphorus (μg/L) 24 (16-33) 60 (35-118) 135 (97-220) 179 (140-404)
Secchi Transparency (feet) 8.9 (5.9-12.8) 4.6 (2.6-7.2) 1.6 (1-3) 2.0 (1-4)
Transparency noted for
swimming impaired (feet) < 6.7 < 5.0 < 3.3 < 3.3
Developed by Heiskary and Wilson (1989; 1990)
13
from 40 μg/L in the Northern Lakes and
Forests to more than 240 μg/L in the Western
Corn Belt Plains. There were similar increases
over the ecoregions for total suspended
solids and nitrate+nitrite nitrogen as
well as depicted in table 3.
3. Fish community structure as an
indicator of water quality
The fish community can also be a reliable
indicator of water quality (Schupp and
Wilson, 1993). Trout have the most critical
requirements for good water quality. They
need well-oxygenated water and prefer
temperatures of 50 to 65 degrees Fahrenheit.
Oxygen must be present below the thermocline
in midsummer—a condition usually
found only in oligotrophic lakes and occasionally
in some mesotrophic lakes.
The closely related whitefish and cisco
(tullibee) are more widespread than trout and
more tolerant of higher temperatures. These
two species are often found in high numbers
in mesotrophic waters (see Carlson Tropic
Status Index, Appendix B).
Most members of the sunfish family also
reach their highest abundance in clear, clean
waters. Where small- or largemouth bass,
rock bass, bluegill and pumpkinseed sunfish
are common, the lake is likely to be in good
condition. Of these, sunfish, smallmouth and
rock bass are usually associated with the
highest quality.
Two other members of the sunfish family, the
black and white crappie, are more tolerant of
a wide range of conditions. Both reach higher
abundances in turbid water than in clear
water. However, the presence of black crappies
should not be taken as a sign of poor
water quality.
Walleye reach their highest abundance in
large, mesotrophic lakes. These lakes frequently
have relatively moderate to low water
clarity, have few rooted aquatic plants and
phosphorus that can lead to
algal blooms. Walleye
usually do not do well in
small lakes with clear water,
the kind favored by bluegill
and largemouth bass.
Northern pike and yellow
perch are the most widespread
species in Minnesota. Northern pike
are generally more abundant in clear water
because vision is an important factor for
feeding pike. The highest perch populations
are usually found in mesotrophic waters and
are associated with
walleye. Perch are more
tolerant of extremes in
trophic state than the
walleye.
Perhaps the best fish
indicators of water
quality are two of the
three bullhead species found in Minnesota:
yellow and black bullheads. Yellow bullheads
are found in the highest numbers in lakes
with clear water. In contrast, black bullheads
reach their greatest abundance in very turbid,
eutrophic waters. Where both species are
present, the ratio of black to yellow bullheads
can serve as an additional indicator of water
quality. In moderately eutrophic lakes, black
bullheads outnumber yellow five to one. A
ratio of two black bullheads to one yellow is
about normal for a mesotrophic lake and in
very clear water yellow bullheads usually
outnumber black bullheads. (Appendix B
contains several graphs that ilustrate the
above information.)
…perhaps the best fish
indicators of water
quality are yellow and
black bullheads.
Table 3: Average annual stream quality measures in parts per billion (μg/L) by ecoregion with
general middle ranges in the parenthesis (i.e., 25th and 75th percentile)
Factor Considered NLF NCHF WCBP NGP
Total Phosphorus (μg/L) 40 (20-50) 90 (60-150) 240 (160-330) 160 (90-250)
Total Suspended Solids 3,300 8,800 27,000 34,000
(1,800-6,000) (4,800-16,000) (10,000-61,000) (11,000-63,000)
Nitrate+Nitrite Nitrogen 30 100 3,900 140
(10-90) (40-260) (1,400-7,400) (10-510)
Developed by McCollor and Heisary (1993)
Trout have the most
critical requirements
for good water
quality…
14
A. Water quality
The water quality of a lake is often the focus
of citizen concerns because it is directly
related to recreation, fisheries, aquatic
vegetation and surface water uses. It is often a
good place to begin when setting lake management
goals and objectives.
The primary agency responsible for managing
the water quality of Minnesota Lakes is the
Minnesota Pollution Control Agency. The
MPCA provides:
(1) statewide monitoring and characterization
of quality – diagnostic and problem assessments.
For example, the statewide lake
monitoring effort works cooperatively with
numerous agencies and hundreds of volunteers
(the Citizens Lake Monitoring and the
Lake Assessment Programs) to characterize
the water quality of about 2,000 of the state’s
lakes.
(2) regulatory controls for point and nonpoint
sources of pollution. Regulation involves
continual refinement of performance standards
for industries, municipalities,
individiual sewage treatment systems, feedlots
and other areas to prevent, control or
abate water pollution as defined by state and
federal laws.
(3) agreements, grants and loans for prevention
and control of water pollution sources.
Grants and loan programs play in an important
role in improving our water resources.
Since 1988, the Clean Water Partnership grant
and loan program has awarded $7.34 million
in investigation and remediation grants and
$12 million in loan projects (septic tanks,
alum treatments etc.) to about 47 different
lake, stream and ground water projects.
(4) technical assistance, education and
technology transfer for the control of point
and nonpoint sources of pollution. The
MPCA also offers extensive technical assistance
to local units of government, citizen
groups, local steering committees, and other
resource management groups and agencies
ranging from the Lake Assessment Program
to acid rain and heavy metal pollution
remediation to watershed corrective actions in
the Clean Water Partnership with local units
and citizen groups. Assistance with the
preparation of lake management plans is
provided from the MPCA’s five regional and
St. Paul offices (see Appendix A for locations
and phone numbers.)
Include water quality goals in the
lake management plan.
Lake management plans should establish
specific short- and long-term numeric indicators
of desired water quality. These will be
performance goals against which actual water
quality can be assessed. It is essential to
collect water quality data as directed in the
Minnesota Lake Data Collection Manual. The
measured average summer total phosphorus
and Secchi transparency can then be compared
against “benchmark” in-lake ecoregion
values, with due consideration by the Technical
Committee to factors such as mean depth
and water flow-through volumes.
Lake water quality goals are usually aimed at
either protecting the current desired uses or
improving the lake through a combination of
watershed best management practices and lake
conditions rehabilitation techniques. Protecting
current uses has often been addressed
through goals such as “maintain
the lake’s existing water quality,
allowing for reasonable year-toyear
variabilities caused by
climate.” Such a goal can be
reinforced with numeric objectives
such as an average summer
Secchi transparency and
the measured variability. It is normal to see
fluctuation of the long-term average transparency
of plus or minus 20 percent (for an
example average summer transparency goal of
5.5 feet +/- 1.1 feet).
Goals for improving water quality are often
identified where there is measured or perceived
deterioration of water quality. Steering
committees may wish to adopt short- and
long-term objectives of for water quality tied
to specific watershed corrective actions. The
approach is to fix what can be reasonably
fixed and then to monitor in-lake water
quality progress against the benchmarks. (See
appendix C for water quality benchmarks and
phosphorus criteria based on ecoregion.) In
general, reservoirs (lakes with very large
IV. Lake management focus areas
Lake water quality
goals are usually
aimed at either
protecting the current
desired uses or
improving the lake.
15
Developing a Lake Management Plan
rus loading to the lake costing about $3 to
$11 per kilogram of reduced phosphorus. All
actions had been implemented by late 1995.
In-lake response to these steps was immediate.
Significant as stream nutrient and sediment
losses to the lake were reduced by about
90 percent. Concurrently measured average
summer total phosphorus concentrations were
noted to drop from 270 to 89 μg/L by 1994.
There was an increase in 1995 to 160 μg/L
due to internal recycling of P within the lake,
which is believed to have been a short-term
event resulting from large changes that have
occurred in this system. Concurrently, there
has been measured a reduction in the intensity
and duration of seasonal algal blooms
with all values less than 20 μg/L. These
trends are expected to continue as the Yellow
Medicine River Watershed District and the
local management groups continue to implement
additional watershed actions.
B. Fisheries
Sportfishing is a vital part of the economy
and the overall quality of life enjoyed in
Minnesota. Each year, two million anglers
take to the water in pursuit of their favorite
species. The 1991 National Survey of Fishing,
Hunting and Wildlife-Associated Recreation
estimated that sportfishing contributes
$846 million to the state’s economy annually
(United States Fish and Wildlife Service,
1991). Wise management of our aquatic
resources is essential to sustaining our rich
sportfishing heritage and the quality of life in
Minnesota.
The best way to protect and improve fish
populations is to protect and improve fish
habitats.
The primary agency responsible for managing
Minnesota’s fish resources is the Minnesota
Department of Natural Resources,
Fisheries Section. There are 28 area fisheries
offices and six regional offices located in
outstate Minnesota (see appendix A for
locations and phone numbers). Area fisheries
managers can provide a wealth of information
pertaining to relative fish populations
and historical lake information. Each year the
MDNR Fisheries Section conducts 500 – 600
fisheries lake surveys. The survey data is
used, along with angler input, to prepare
formalized fisheries management plans for
individual waters.
watersheds) or shallower lakes (less than
about 35 feet maximum depth), may be
expected to have greater nutrient concentrations
and lower transparencies.
Case Study: Lake Shaokatan Restoration
Project
Lake Shaokatan is a shallow prairie lake in
west central Lincoln County, Minnesota. Its
water quality deteriorated severely in the
1980s due to excessive nutrient loading
associated with watershed land use practices.
Nuisance algal blooms dominated the open
water season and had occasionally produced
algal toxins resulting in the death of dogs and
cattle. An extensive data gathering effort
began in 1991to understand watershed
nutrient loading and lake response dynamics.
Through the use of seven state-of-the-art
stream measurement sites, water and mass
loading estimates were obtained and lake
system balances determined. The basic
approach was to manage the lake water
quality by determining and managing the lake
nutrient budget to achieve an average in a
lake total phosphorus goal of 90 μg/L (as
suggested by the ecoregion information
summary in Appendix C).
Lake Shaokatan has a surface area of 1,018
acres and a mean depth of 7.3 feet and
receives water from an 8,054-acre watershed.
A Clean Water Partnership project begun in
1990 found extremely elevated total phosphorus
(average summer value of 270 μg/L).
Chlorophyll-a concentrations were episodic
with concentrations noted to exceed 100 μg/L
with summer means of 20-30 μg/L.
After completion of the monitoring effort, a
detailed watershed restoration program was
initiated in late 1991, consisting of:
a) Diversion of a stream away from a swine
operation;
b) Rehabilitation of the feedlot impacted
wetland;
c) Buy out of a swine operation and elimination
of this as a nutrient source to the
lake;
d) Upgrading of another dairy feedlot
operation;
e) Upgrading of shoreline septic systems;
and
f) Rehabilitating four wetland complexes in
the watershed.
These implementation actions resulted in
excess of a 58 percent reduction in phospho16
Groups that fully implement strategies to
improve water quality will aid fish
habitat protection. Critical shorelines can
be protected or restored through good
landowner management or public ownership.
Other activities include aquatic
plant restoration, aeration of winterkillprone
lakes, and removal of dams that
limit fish access to important habitats.
Stocking. When the fisheries manager
determines that stocking is necessary,
groups can help with cost-sharing rearing
pond expenses, forage costs or equipment
needs.
Regulations. Support of regulations to
improve fishing quality is critical to the
success of maintaining good fishing.
This includes limiting the introduction of
exotic species that may harm fish habitats
(see Exotic Species).
Contact the DNR Area Fisheries Manager for
an example of a fish management plan.
C. Aquatic Vegetation
Rooted aquatic plants are a natural part of
most lake communities and provide many
benefits to fish, wildlife and people. They are
one of the primary producers in the aquatic
food chain, converting the basic chemical
nutrients in the water and soil into plant
matter that becomes food for other aquatic
and terrestrial life.
Aquatic plants have many other important
functions, including:
improving water quality by trapping nutrients;
protecting shorelines and lake bottoms by
decreasing wave action; and
improving aesthetics by adding to the
biodiversity of the lakeshore.
While aquatic plants perform these important
functions, they can also interfere with various
uses of the lake if their growth is profuse.
Control of aquatic plants is appropriate when
reasonable access to, and the use of the water
is impeded.
Aquatic plant management is defined as those
activities intended to alter an aquatic plant
community, either to reduce or increase the
abundance of plants in a specified area (e.g.,
through harvesting or planting).
Consider fisheries in a lake
management plan.
The goal of fisheries management is to
protect and restore of fish habitats. The DNR
guidelines for preparing a fisheries management
plan include Fisheries Management
Planning Guide for Streams and Rivers and
the Lake Management Planning Guide (see
reference section). Area fish managers work
closely with individual lake associations
when developing fish management plans.
First an inventory of the fishery resources
and aquatic habitats is conducted. Then the
fisheries manager, in consultation with
established groups interested in the management
of the lake (e.g., lake association),
develops realistic management goals. These
goals are based on the inventory data,
historical information and the ecological
potential of the lake or stream. Then an
operational plan is developed that identifies
the actions that will be taken to achieve the
management goals identified. Actions may
include such things as habitat protection and
improvement, stocking, experimental regulations
or public access development. Finally,
the management goals and operations plan
are evaluated to determine if
they need to be adjusted to
build upon what has been
learned. For example, evaluation
of fish stocking in Minnesota
has provided insight about
its success in different types of
lakes. Fisheries management is a dynamic
process that must be continually evaluated
and refined.
Associations, clubs and local units of government
have many avenues to participate in
fisheries management. Sharing your interests
and concerns with the fisheries manager is
important in the development of the fisheries
management plan. Consulting with the area
fisheries manager will help target the most
important fish-related activates to undertake.
Some examples of fish management related
activities include:
Inventory. Angler information on fish
populations can be important in understanding
the status of a population. For
example, angler diaries can provide
valuable information on muskellunge and
largemouth bass populations.
Habitat protection/restoration. This is the
primary area where the long-term health
of fish communities can be ensured.
Fish management plan:
Inventory resources
Set goals
Identify actions
Evaluate plan
17
Developing a Lake Management Plan
Generally, the aquatic vegetation section of a
lake management plan becomes more important
as the lake’s shoreline becomes heavily
developed.
A strategy for lake-wide management of
aquatic plants has been particularly helpful
where:
1. Lakes have a large littoral zone with
extensive beds of submerged aquatic
plants. These lakes usually have a long
history of extensive aquatic plant control
projects and lakeshore owners complain that
not enough control is allowed for
them to fully utilize the lake’s
water surface.
2. Lakes have stands of bulrush, wild rice,
cattail and other emergent vegetation that are
in jeopardy of being lost due to shoreline
development. Lakeshore owners, as well as
fish and wildlife managers, are concerned
with the loss of these important habitat types
and wish to do something to preserve them.
3. Lakes have floating bog problems.
When pieces of bog break loose due to
fluctuating water levels or illegal removal
activities, they can destroy property and can
be a hazard to navigation.
The primary agency responsible for managing
aquatic plants in Minnesota is the Minnesota
Department of Natural Resources,
Division of Fish and Wildlife, Section of
Fisheries. Aquatic plants growing in public
waters below the ordinary high water level
belong to the state and there are limits placed
on the type and amount of control lakeshore
owners can do. Many aquatic plant management
activities require a permit. For example,
permits are required for activities that control
emergent vegetation, such as cattails, wild
rice or bulrush, or any time aquatic pesticides
are used in public waters. The Section of
Fisheries also surveys aquatic plants when
they prepare fisheries management plans.
Contact the Area Fisheries Manager for
information about a lake’s vegetation or other
characteristics.
Consider aquatic plant management in a
lake management plan.
When developing a lake management plan
there are several types of aquatic vegetation
to consider. Management of each type is
different. There are four categories:
Algae have no true roots, stems or leaves,
and range in size from tiny, one-celled
organisms to stringy filamentous types.
Plankton algae, which consist of free
floating microscopic plants, grow
throughout both the littoral zone and the
well-lit surface water of an entire lake.
Submerged plants have stems and leaves
that grow entirely underwater, although
some may also have floating leaves.
Flowers and seeds on short stems that
extend above the water may also be
present. Submerged plants grow near
shores to the deepest part of the littoral
zone and display a wide range of plant
shapes. Depending on the species, they
may form a low-growing “meadow” near
the lake bottom, grow with lots of open
space between plant stems, or form dense
stands or surface mats.
Floating-leaf plants are often rooted in the
lake bottom, but their leaves and flowers
float on the water surface. Water lilies are
a well-known example. Floating leaf
plants typically grow in protected areas
where there is little wave action.
Emergent plants are rooted in the lake
bottom, but their leaves and stems extend
out of the water. Cattails, bulrushes and
other emergent plants typically grow in
wetlands and along the shore where the
water is less than 4 feet deep.
In many cases a small amount of control to
allow access by individual landowners is all
that is required to deal with aquatic vegetation
issues. However, when issues become
more complex and involve many, if not all,
property owners, then it is time to develop an
aquatic vegetation section for the lake
management plan.
To develop an aquatic plant management
section for a lake management plan, contact
the MDNR area fisheries office. The fisheries
manager or aquatic plant specialist will work
cooperatively with representatives of other
agencies (e.g., MPCA, SWCD), lakeshore
owners and other concerned groups from the
community to develop this section. Many of
these representatives will have valuable
information about the lake, including the
18
amount and types of vegetation present,
fisheries, bottom types, shoreline development,
water clarity and other information that
may help to identify trends or changes in the
lake environment. The fisheries manager will
also be able to identify important habitat and
other sensitive areas in the lake. Including an
aquatic vegetation section in the lake management
plan provides an opportunity to
protect the future health of the lake as well as
allow for multiple recreational uses.
Case study; Big Birch Lake
Big Birch Lake in Todd County is a good
example of how a Lake Vegetation Management
Plan (LVMP) can be used to address
lake management issues. Big Birch is highly
developed. The northwest shoreline and an
area called Hunter’s Bay have a band of
cattails 100 to 300 feet wide and bulrushes
extending into the deeper water. Members of
the lake association were concerned that the
cattails and bulrush were being illegally
destroyed as these areas were being developed.
The lake association met with the
aquatic plant specialist and cooperatively
developed an LVMP that will help protect
aquatic vegetation and the lake environment.
The lake association is using the plan and
information from the DNR to educate other
shoreline property owners about the value of
aquatic vegetation and the appropriate ways
to obtain access to the lake.
D. Wildlife
Minnesota’s lakes are home to many species
of wildlife. From our famous loons and bald
eagles to muskrats, otters and frogs, wildlife
is an important part of our relationship with
lakes. In fact, Minnesota’s abundant wildlife
can be attributed largely to our wealth of
surface water. From small marshes to large
lakes, these waters are essential to the survival
of wildlife.
The most important wildlife habitat begins at
the shoreline. The more natural the shoreline,
with trees, shrubs and herbaceous vegetation,
the more likely that wildlife will be there.
Just as important is the shallow water zone
close to shore. Cattail, bulrush and wild rice
along the shoreline provide both feeding and
nesting areas for wildlife. Loons, black terns
and red-necked grebes are important Minnesota
birds that are particularly affected by
destruction of this vegetation. Underwater
vegetation is also important to wildlife for
many portions of their life cycle, including
breeding and rearing of their young.
The primary agency charged with the management
of Minnesota’s wildlife is the
Department of Natural Resources, Division
of Fish and Wildlife, Wildlife Section.
DNR Area Wildlife Managers and Regional
Nongame Wildlife Specialists are located
across the state. (Please refer to Appendix A
for the location and telephone number of
regional and area offices.)
Incorporate wildlife in a lake
management plan.
Lake management plans are a valuable tool
for considering the future of the wildlife
resources in and around your lake and its
watershed. The DNR can provide advice on
how to identify and inventory the existing
wildlife. This inventory of wildlife, and the
habitat areas they use, will help set lake
management goals that protect and enhance
this important resource. Wildlife population
goals are best achieved by creating and
protecting critical habitat areas on your lake.
Wildlife will also benefit from efforts to
improve the lake’s watershed. Like the lake
itself, wildlife considerations extend beyond
the water’s edge. Aquatic wildlife often spend
part of their time in streams, wetlands and
upland areas some distance from the lake. In
many cases, the availability of this habitat is
critical to their survival. The buffer areas
along the edges of inlet streams and upstream
lakes and wetlands provide travel corridors
for wildlife. These corridors are particularly
important for song birds, frogs and turtles.
Protection and restoration of wetlands is
critical to both fish and wildlife as well as to
improving the quality of water flowing into
the lake.
Shallow lakes occurring in the watershed are
important wildlife areas and are often spawning
areas for fish. These lakes suffer from the
same factors as the downstream lakes they
contribute to. The restoration and protection
of aquatic vegetation in these areas is key to
improving their quality and the quality of the
runoff that ends up downstream. The DNR
Wildlife Section will help to evaluate these
shallow lakes and recommend management
ideas. These lakes can even be designated as
wildlife management lakes through a public
hearing process if conditions warrant.
Some examples of actions to accomplish
wildlife goals and objectives in the lake
management plan include:
19
Developing a Lake Management Plan
this area by working through the Reinvest in
Minnesota Critical Habitat program with
matching funds. As a state-owned Aquatic
Management area, the shoreline will be
managed by DNR- Fisheries. The lake association
has continued its efforts by working
with the DNR Nongame Wildlife Specialist to
erect nesting platforms for ospreys and loons,
as well as nesting boxes for wood ducks,
goldeneyes, and hooded mergansers.
E. Exotic Species
For the purposes of this manual, the term
“exotic species” means a plant or animal not
native to Minnesota, or one that was introduced
to Minnesota after 1800.
Many aquatic exotic species present in Minnesota
are the result of intentional introductions.
The brown trout, rainbow trout and chinook
salmon were introduced to provide a unique
fishing experience to Minnesota anglers.
Although there is some debate, the introduction
of these species is generally perceived as
beneficial. The common carp, another introduced
species, was originally thought to be a
boon for anglers because it could tolerate
degraded habitat conditions, grew rapidly and
was easy to catch. The carp, established in
most of the major watersheds of North
America, is now often considered a pest, and
is blamed for degradation of habitat in
marshes, lakes and streams.
Harmful exotic species may also be introduced
unintentionally into Minnesota’s lakes and
rivers. For example, the spiny water flea,
zebra mussel, ruffe and white perch were all
probably introduced into the Great Lakes from
ballast water discharged from ships travelling
from European ports. Eurasian watermilfoil,
an exotic water plant, has spread from coast to
coast on boats, trailers, bait buckets and
perhaps even by waterfowl. How this aquatic
plant arrived in the U.S. is uncertain.
Establishing no wake zones or seasonal
sanctuaries will help to control disturbances
to nesting wildlife in critical
areas.
Adding artificial nesting structures for
loons, and houses for other species will
help to preserve the lake’s wildlife
resource.
Work to preserve areas by entering into
landowner agreements or conservation
easements with landowners in the watershed.
Explore the possibility of helping the state
acquire land for Aquatic Management
Areas or Wildlife Management Areas.
Contact the DNR Area Wildlife Manager for
actions tailored to the local resources.
Case study: Big Sugar Bush Lake,
Kabekona Lake
The peninsula on Big Sugar Bush Lake in
Becker County was popular with lakeshore
owners who enjoyed the wildlife using the
area. Its 18 acres of maple, basswood and
aspen were interspersed with a number of
century-old white pines. The Big Sugar Bush
Lake Association purchased the area and
donated it to the DNR as a wildlife management
area. The donation not only protects this
undeveloped lakeshore for osprey, wood
ducks, loons and other wildlife, but was
matched with the Reinvest in Minnesota
Critical Habitat program to provide funds to
help protect other areas. The lake association
is currently working with the DNR Nongame
Wildlife Specialist to establish a wildlife
interpretive project on the peninsula.
On the north shore of Kabekona Lake in
Hubbard County are 3 acres of natural
shoreline near a bald eagle nest. Bulrushes in
the shallow water provide both fish and
wildlife habitat, while behind an ice ridge,
the tamarack, spruce, ash and dogwood
provide warblers and other songbirds with
nesting and feeding areas. The Kabekona
Lake Association has ensured protection of
purple
loosestrife
ruffe
flowering rush
spiny water flea
curly-leaf pondweed
zebra mussel
round goby
Eurasian
watermilfoil
20
Introducing species accidentally or intentionally
from one habit to another is risky business.
Freed from the predators, parasites,
pathogens and competitors that keep their
numbers in check, species introduced into
new habitats often overrun their new home
and crowd out native species. In the presence
of enough food and a favorable environment,
their numbers will increase rapidly. Once
established, exotics are rarely eliminated.
Exotic species have the potential to cause
several problems. They can reduce the
abundance of native species by out-competing
them for food or space. Wildlife that depends
on native species for food, cover and nesting
sites may be faced with habitat of lower, if not
unacceptable, quality. Initially, the impact of
exotic species on native plant and animal
communities are unclear; it may take years for
it to become fully apparent. Exotic species
also affect recreation and economic activities.
The primary agency responsible for managing
exotic aquatic species in Minnesota is the
Minnesota Department of Natural Resources,
Division of Fish and Wildlife,
which manages the Harmful Exotic Species
Management Program. They can provide
information on exotic species, and their
ecology, biology, and on the location of
existing populations in Minnesota. They also
have information on current exotic species
laws and rules and on control of species such
as purple loosestrife and Eurasian
watermilfoil. Much of this information is
summarized in the Exotic Species Handbook
listed in the reference section of this manual.
Consider exotic species in a lake
management plan.
The first step in designing exotic species
control for a lake management plan is to
complete an assessment of the current level of
infestation. Depending on the phase of
infestation in a particular lake, there are
several actions that can be identified in the
lake management plan:
Phase I – No known infestations of exotic
species. When no harmful exotic species have
been observed, the focus of the exotics
component of a lake management plan should
be education aimed at prevention. This
includes training on the identification of
exotic species, the risks involved in their
introduction and how to prevent their spread.
Regular monitoring to identify an exotic
introduction is also recommended
Phase II – Intensive Management. Consider
these management strategies where a new
exotic species has been recently identified
and the possibility of containing or eliminating
the population still exists. In this situation,
the lake management plan would likely
identify three actions:
1. Implement control measures in coordination
with the DNR;
2. Keep lake residents and users informed
of the changing situation and special
regulations that may apply; and
3. Monitor the effectiveness of control
efforts in coordination with the DNR.
Phase III – Maintenance management. If
harmful exotic species are already well
established, outline strategies to reduce the
recreational, economic or ecological magnitude
of their impacts in the lake management
plan. These efforts will often be concentrated
where exotics cause the most problems,
interfere with the lake use, or can be easily
spread. The DNR’s Harmful Exotic Species
Management Program can provide assistance
with these management activities.
Case study: Bay Lake
Bay Lake in Crow Wing county is a good
example of how exotic species management
can be implemented cooperatively by local
and state interests. In the fall of 1992, a
lakeshore resident spotted a suspected
Eurasian watermilfoil plant and contacted the
DNR Regional office in Brainerd. A DNR
aquatic plant management specialist inspected
the site, and within one week the
plant was positively identified as Eurasian
watermilfoil. It was confined to a small
portion of the lake, which was treated with
herbicide. In 1993, the lake was inspected
several times by the aquatic plant management
specialist and the lake association; only
one Eurasian watermilfoil was found, and it
was removed. In 1994, milfoil was found on
several sites, and during 1995 spread to about
10 sites occupying nearly 100 acres, most of
which were treated with hericide. The DNR
trained the lake association in aquatic plant
identification and survey techniques, and the
association organized their own lake monitoring
program. Association members were also
trained on how to conduct public awareness
events at the public access to prevent further
introductions of exotic species.
21
Developing a Lake Management Plan
F. Land Use and Zoning
The amenities associated with living on a
lake, including many recreational opportunities
and aesthetic rewards, place lakeshore
property in high demand for home sites and
certain commercial businesses such as resorts
and marinas. However, not all lands surrounding
a lake may be suited for such
development. Proper planning is essential to
ensure that development will occur in a safe
and orderly fashion, and with minimal impact
on the lake.
The state Shoreland Management Act establishes
a set of minimum development standards
specifically for shoreland areas.
Shorelands are defined as lands located
within 1,000 feet of a lake, pond or flowage,
and within 300 feet of a river. Shoreland
standards are adopted and administered by
local governments and are commonly incorporated
into their overall zoning controls.
Like zoning controls, shoreland standards set
permissible uses and specify minimum
requirements for newly created lots.
Shoreland standards may also limit physical
alterations to shoreland property, and may
control the placement of structures, roads and
other improvements to minimize impacts on
the adjoining lake.
The primary agency responsible for land use
controls and zoning in Minnesota is local
units of government such as counties,
municipalities or townships. They have the
authority to administer land use zoning
controls for areas within their boundaries.
Local zoning controls generally apply to all
lands in the government unit’s jurisdiction,
including lakeshore. These controls may
identify a list of uses that are permissible or
non-permissible for given areas or “zones.”
They also may specify minimum design
standards for newly created lots, onsite sewer
systems and wells, subdivision plats, planned
unit developments and for construction in
general.
Most local governments also administer
regulations pertaining to the use of floodplain
areas. Floodplain regulations specify minimum
elevation requirements for structures
and access roads and limit certain types of
uses in floodplain areas. Such controls are
particularly important on lakes with large
watersheds, or lakes which exhibit extreme
water level fluctuations. Generally, if a local
government is administering floodplain
regulations, then floodplain areas along some
lakes and rivers have been mapped. Copies of
Flood Insurance Rate Maps are available
from the county or municipal zoning offices
or the DNR Area Hydrologist.
Consider land use controls and zoning
regulations in a lake management plan.
Since local governments have the legal
authority to adopt land use regulations, the
planning process begins with a contact to the
local planning and zoning administrator. The
lake management planning group, with the
help of the administrator,
should use the list of planning
considerations to determine the
best suited uses for a particular
zone or district (e.g., planned
development vs. open space for
wildlife).
Before designing a set of land
use controls for a lake it is important to
inventory the landscape features that influence
the lake’s water quality and its ability to
sustain fish and wildlife. While shoreland
standards generally apply only to lands
within 1,000 feet of a lake, planners might
want to consider the entire watershed of the
lake in their planning efforts since activities
anywhere within the watershed have the
potential to impact the lake. Some of the
resources that should be inventoried include:
Wetlands. Wetlands serve as filters to
remove nutrients and sediments from surface
runoff before they reach the lake. They also
provide important habitat for many species of
wildlife. Wetland vegetation along a
lakeshore provides habitat for fish and
wildlife and protects the shore from erosion
caused by wave action. Wetlands are also
protected by various federal, state or local
laws. Wetlands have been mapped on a series
of National Wetland Inventory Maps. These
maps may be viewed at the local Natural
Resources Conservation Service office or at
the soil and water conservation district office.
Bluffs and steep slopes. Lands characterized
by bluffs and steep slopes can become a
serious erosion threat if they are disturbed by
grading, filling or vegetation removal. Bluffs
are already protected from intensive removal
of vegetation and grading or filling involving
more than 10 cubic yards of material by local
shoreland management ordinances. Bluffs
rise at least 25 feet above the lake at an
average slope of 30 percent or greater and
can generally be identified from topographic
maps the U.S. Geological Survey (USGS)
Quadrangle Maps. Such maps can be ob-
Shoreland standards
are adopted and
administered by local
governments and are
commonly incorporated
into their overall
zoning controls.
22
public accesses, parks, marinas, highways
adjacent to lakes, private septic systems and
municipal sewage discharges and float-plane
airports.
The inventory can be used to determine the
best uses for individual tracts of shoreland or
other critical areas identified. A set of written
standards can be developed to guide future
use of these lands. Generally, this entails the
designation of land use districts or zones
around the lake and the preparation of a list
of permissible, conditional and prohibited
uses for each district. The districts must be
shown on the zoning maps of the local
government and district boundaries must be
definable to a specific feature (e.g., property
line, highways, government lot line, etc.).
For each district or zone, it is necessary to
develop a specific list of performance standards.
These will establish minimum guidelines
for development and may include such
things as minimum lot sizes and building and
sewage system setbacks from the lake. When
the intended uses for the land have been
determined and the performance standards
defined, these documents are presented in
draft at a public hearing conducted by the
local planning commission or board to
determine if there is any need to add, amend
or eliminate portions of the plan. After the
plan has cleared the hearing process, it
becomes part of the zoning ordinance and has
the force and effect of law.
Possible sources of funding for land use
planning activities may include the local
government or the soil and water conservation
district. Active lake associations may
also have an operating budget to fund certain
aspects of the process
The shoreland management program’s goal is
for each newly created lot in shorelands to be
suited in its natural state for the intended use.
If that use is for development of a homesite,
then each lot should have enough land that is
free of limiting factors such as wetlands and
bluffs to accommodate the placement of all
proposed structures, an onsite water supply
well and sewage disposal system and a site
for future replacement of the sewage system.
In addition, the property should be accessible
by road. The presence of bluffs, wetlands or
other surface water features may restrict the
ability to extend roadways into certain areas.
G. Managing water
tained from the USGS or may be viewed at
County or Municipal offices (Zoning or Land
Department) or at local offices of the DNR.
Shallow groundwater or bedrock. The
presence of the groundwater table or bedrock
at or near the soil surface limits certain
construction activities, particularly onsite
sewage disposal systems.
Soils. Some soils have poor drainage or
stability characteristics that affect their ability
to support development of roads, buildings or
onsite sewage disposal systems. In most
Minnesota counties, soils have been mapped
as part of the County Soil Survey. These
surveys classify the soil types and explain the
limitations of each type for development
purposes. They also provide information on
seasonal high groundwater levels and shallow
bedrock. They surveys are available from the
county soil and water conservation district
office or the USDA Natural Resources
Conservation Service.
Important habitat areas. Areas that support
high quality fish or wildlife habitat or rare
plants and animals generally need buffer
areas surrounding them where disturbances
will be minimized. Therefore, the locations of
such areas should be determined and their
protection should be reflected in land use
plans. Information on these resources can be
obtained from the MDNR Area Fisheries and
Wildlife Manager.
Cultural and historic sites. These include
sites of known archeological significance,
unplatted cemeteries and historic structures.
Shoreland areas are generally more likely to
have sites of historic cultural significance
than non-shoreland areas. Information on
known sites or the potential for such sites to
exist in an area can be obtained from the
Minnesota Historical Society or the office of
the State Archeologist.
Additional areas that should be considered
when examining land use in a watershed are:
23
Developing a Lake Management Plan
surface use conflicts
The goal of lake management is to ensure
that the lake can continue to provide the
benefits that attract homeowners and users.
However, conflicts among uses arise almost
invariably. Successful resolution of conflicts
lies in the ability of the users to work
collaboratively to arrive at acceptable compromises.
The primary agency responsible for managing
surface water use conflicts is the Minnesota
Department of Natural Resources,
Bureau of Information and Education.
The Boat & Water Safety Section within
the Bureau oversees surface water use and is
in charge of administering the Water Surface
Use Management (WSUM) program. The
goal of this program is to enhance the
recreation use, safety and enjoyment of the
water surfaces in Minnesota and to preserve
these water resources in a way that reflects
the state’s concern for the protection of its
natural resources.
Consider surface use management in a
lake management plan.
Any governmental unit may formulate,
amend or delete controls for water surface
use by adopting an ordinance. Submit the
ordinance for approval by the MDNR Boat
and Water Safety Coordinator 1-800-766-
6000, or in the metro area 296-3336.
The ordinance must:
where practical and feasible, accommodate
all compatible recreational uses;
minimize adverse impacts on natural
resources;
minimize conflicts between users in a way
that provides for maximum use, safety and
enjoyment; and
conform to the standards set in WSUM
Rules.
The WSUM rules establish standards to
promote uniformity of ordinances or rules on
the use of watercraft throughout the state. In
addition, they encourage compliance and
ease of enforcement. It is not required that all
the WSUM standards be included in the
ordinance, only those necessary to reduce the
conflict. The governmental unit may select
from the following standards:
Watercraft type and size. Controls may be
formulated for the type and/or size of watercraft
permissible for use on the surface of the
water body or portion of the water body.
Motor type and size. Controls on the maximum
total horsepower of motor(s) powering
watercraft will utilize one or more of the
following options: 25 hp; 10hp; electric
motors; no motors.
Direction of travel. Directional controls, if
used, will mandate watercraft to follow a
counterclockwise direction of travel.
Speed Limits. Controls concerning the
maximum watercraft will utilize one or more
of the following miles-per-hour cutoffs: slow
no wake, 15 mph or 40 mph.
Effective time. Controls must use one or
more of the four time periods specified in the
rules.
Area zoning. Controls will clearly specify
which portion of the water body is affected
by the control.
The formal review process begins when the
local unit of government submits the following
information to the DNR Bureau of
Information and Education for review and
approval, prior to adopting an ordinance as
required by the rules:
water surface worksheet with a map of the
lake highlighting the areas to be regulated;
a statement evaluating whether the information
reveals significant conflicts and
explains why the particular proposed
controls were selected (i.e., provide
adequate justification for the adoption of
the controls);
the proposed ordinance; and
description of the public hearing held
concerning the proposed controls, including
an account of the statement of each
person who testified.
If more than one governmental unit is involved
in adopting the ordinance, all the
governmental units with jurisdiction over the
particular water body must agree with the
ordinance and develop a joint powers agreement.
If for some reason the DNR denies the
proposed ordinance, the denial will be in the
form of a letter which will explain the
reasons for denial. The governmental unit
may amend the proposed ordinance and
resubmit the proposed ordinance for a second
review by the MDNR.
24
The DNR will notify the governmental unit
in writing of approval or denial within 120
days after receiving all of the above information.
Failure of the DNR to notify the governmental
unit will be considered approval. The
governmental unit adopting an ordinance
must provide for notification of the ordinance
to the public, which involves placing signs at
public watercraft launch sites outlining
essential elements of the ordinance.
H. Public water access
Research has shown that Minnesotans rely
heavily upon public access sites to access
lakes and rivers. A 1988 boater survey
conducted by the University of Minnesota
showed that three-fourths of the state’s boat
owners launch a boat at a public water access
site at least once a year. In addition, over 80
percent of boat owners report using public
water access sites for recreation activities
other than boating.
The primary agency responsible for public
water accesses in Minnesota is the Minnesota
Department of Natural Resources
Trails and Waterways Unit. They are
responsible for the acquisition, development
and management of public water access sites.
The DNR either manages them as individual
units or enters into cooperative agreements
with county, state and federal agencies, as
well as local units of government such as
townships and municipalities.
The DNR’s efforts to establish and manage
public water access sites are guided by
Minnesota Statutes and established written
DNR policy. The goal of the public water
access program is free and adequate public
access to all of Minnesota’s lake and river
resources consistent with recreational demand
and resource capabilities to provide
recreation opportunities.
Consider public access sites in a lake
management plan.
The DNR is also on the alert for properties
that are being sold that may be used as a boat
access. Site usability is based upon a set of
criteria designed by the DNR. The pricing is
based upon fair market value. When developing
a lake management plan, it would be wise
to identify sites that may be suitable for a
public access.
If a desirable site is identified, construction is
usually performed by a local contractor
according to DNR specifications. There are
several criteria that the public access must
meet to be approved by the DNR. Contact the
local DNR Trails and Waterways office in St.
Paul for more information on the construction
and design of public accesses.
The DNR routinely works with interested
parties in the design of access sites from the
initial concept stage through final design.
This cooperative process does not end with
the construction of the access site. After the
access is developed, the Trails and Waterways
Unit will continue to work with the
community and neighbors on issues regarding
maintenance and operation procedures.
Lakes are a very important part of Minnesotans’
well being and economic diversity. One
25
of the state’s most important products is the
“water experience” and it directly influences
property values, recreation, tourism and
related activities. As in any product, quality is
important and Minnesota competes for
limited discretionary dollars with Wisconsin,
Michigan and Canada. People will go elsewhere
if our product is not competitive.
The quality of our lake resources is the
cumulative result of the people and their
activities within the lake’s drainage basin.
And, with ever increasing pressures upon our
lakes, they cannot be expected to assimilate
all impacts forever. The need to manage lakes
as a limited resource requiring purposeful
planning and action is real and immediate.
Lake management requires the collective
resources of citizens, local, county and state
governments and commercial enterprise.
Neglect often results in negative impacts,
water quality declines, lost fisheries and
ultimately lost revenues and a degraded
quality of life. Lake rehabilitation is a very
costly venture with an uncertain outcome.
Citizen-initiated steering committees
havebeen an effective method for developing
specific lake and watershed management
plans. These efforts may be expected to
require a year or more to prepare and up to
several subsequent years to enact changes in
the daily lives of watershed residents. Cooperation,
collaboration and a willingness to
change are the prime ingredients of the
successful ventures. Finger pointing and
recrimination will quickly ruin the best of
intentions.
Formalized lake plans should be acknowledged
by and incorporated into county,
township, watershed district or other units of
government operations—particularly those of
the planning and zoning departments. Chipping
away at the problems does work and
everyone can do something, no matter how
small the efforts may seem. It all adds up and
makes a difference over time!
VI. References
V. Conclusion
26
Lake Management – General
Data Information Committee, Lakes Task Force and the Environmental Quality Board. 1994
Minnesota Lake and Watershed Data Collection Manual. Available through the Minnesota
Lakes Association, 1-800-515-5253 begin_of_the_skype_highlighting 1-800-515-5253 end_of_the_skype_highlighting begin_of_the_skype_highlighting 1-800-515-5253 end_of_the_skype_highlighting. $10 + 3 shipping.
Dresen, M. D. and Korth, R.M. 1994. Life on the Edge… Owning Waterfront Property.
University of Wisconsin College of Natural Resources. (715) 346-2116. $3.
Freshwater Foundation and Minnesota Pollution Control Agency. 1985. A Citizens Guide to
Lake Protection. Available through the MPCA (612) 296-6300 or Freshwater Foundation
(612) 471-8407. Free.
Heiskary, S. A. and C. B. Wilson. 1989. The regional nature of lake water quality across
Minnesota: an analysis for improving resource management. MN Jour. Acad. Sci.:55(1)
71-77. Available through the MPCA Water Quality Division. (612) 296-7202.
McComas, Steve. 1993. Lakesmarts: The first lake maintenance handbook. Terrene
Institute. Available through Blue Water Science, 550 S. Snelling Ave., Saint Paul, MN
55116, (612) 690-9602. Price $18.95, major credit cards accepted.
New York State Department of Environmental Conservation. 1990. Diet for a Small Lake: A
New Yorker’s Guide to Lake Management. Federation of Lake Associations, Inc. Rochester,
New York.
U.S. EPA. 1988. Lake and Reservoir Restoration Guidance Manual. First ed. EPA 440/5-
88-002. (202) 382-2090. Free.
U.S. EPA. 1990. Monitoring Lake and Reservoir Restoration. Technical Supplement to
the Lake and Reservoir Restoration Guidance Manual. EPA 440/4-90-007. (202) 382-
2090. Free.
Watershed Management – Land Treatment
Arrowhead Water Quality Team. 1996. Video: “Keeping Our Shores” and “Protecting
Minnesota Waters” fact sheets (18). Lake County SWCD, Box 14, Two Harbors, MN
55616 (218) 834-6638. $20 + tax.
Arrowhead Water Quality Team. 1996. Protecting Minnesota Waters: Shoreland Best
Management Practices. Minnesota Extension Service, Duluth (218) 726-7512.
Conservation Technology Information Center (CTIC). Six-pamphlet series compiled as part
of the Know Your Watershed Campaign:
Getting to Know Your Watershed; Managing Conflict; Building Local Partnerships; Putting
Together a Watershed Management Plan; Leading and Communicating; Reflecting on
Lakes. Available through the CTIC at 1220 Potter Drive, Room 170, West Lafayette, IN
47906 (317) 494-9555. $2 per pamphlet.
Conservation Technology Information Center. 1994-5. Nonpoint Source Water Quality Contacts.
(317) 494-9555.
Minnesota Pollution Control Agency. 1991. Agriculture and Water Quality: Best Management
Practices for Minnesota. Available through the MPCA Water Quality Division (612)
27
Developing a Lake Management Plan
296-7202. Free.
Minnesota Pollution Control Agency. 1988. Protecting Minnesota’s Waters . . . The Land-
Use Connection. Available through the MPCA (612) 296-6300. Free.
Tip of the Mitt Watershed Council. 1995. Understanding, Living with and Controlling
Shoreline Erosion: a Guidebook for Shoreline Property Owners. Conway, Michigan
(616) 347-1181. Shipping/handling fee approx. $3.
Fisheries
Minnesota Department of Natural Resources. 1982. Lake Management Planning Guide.
MDNR Division of Fish and Wildlife, Section of Fisheries, Special Publication 131, Saint
Paul, MN (612) 296-3325. Free.
Minnesota Department of Natural Resources. 1993. Manual of Instructions for Lake Survey.
MDNR Division of Fish and Wildlife, Section of Fisheries, Special Publication 147, Saint
Paul, MN (612) 296-3325. Free.
Minnesota Department of Natural Resources. 1993. Fisheries Management Planning Guide
for Streams and Rivers. MDNR Division of Fish and Wildlife, Section of Fisheries,
Special Publication 148, Saint Paul, MN (612) 296-3325. Free.
Schupp, D. H. 1992. An Ecological Classification of Minnesota Lakes with Associated Fish
Communities. MDNR Division of Fish and Wildlife, Section of Fisheries, Investigational
Report 417, Saint Paul, MN (612) 296-3325. Free.
U.S. EPA. 1993. Fish and Fisheries Management in Lakes and Reservoirs. Technical
Supplement to the Lake and Reservoir Restoration Guidance Manual. EPA 841-R-93-
002. (202) 382-2090. Free.
U.S. Department of the Interior and U.S. Department of Commerce. 1993. 1991 National
Survey of Fishing, Hunting and Wildlife-Associated Recreation (Minnesota). U.S.
Government Printing Office, Washington D.C. Free.
Aquatic Vegetation
Minnesota Department of Natural Resources. 1994. A Guide to Aquatic Plants. MDNR
Division of Fish and Wildlife. Ecological Services Section, 500 Lafayette Road, Saint Paul,
MN 55155-4025 (612)296-2835 Metro Area; 1-800-766-6000 Toll-Free in Minnesota. Free.
Exotic Species
Minnesota Department of Natural Resources. Exotic Species Handbook. MDNR Division of
Fish and Wildlife, Ecological Services Section, 500 Lafayette Road, Saint Paul, MN 55155-
4025 (612) 296-2835 Metro Area; 1-800-766-6000 Toll-Free in Minnesota.
Other
Minnesota Department of Natural Resources, 1995. A User’s Guide to the Minnesota Natural
Heritage Information System. Minnesota Natural Heritage and Nongame Wildlife Programs,
500 Lafayette Road, Saint Paul, MN 55155-4025 (612) 296-8279 or 296-8319. Free.
28
Appendices
Appendix A – Water quality indices
Carlson Trophic Index
Fish Community Structure Graphs
Appendix B – Lake water quality benchmarks based on ecoregion
CARLSON’S TROPHIC STATE INDEX VALUES
TSI Relationships based on mean summer data for 1991.
Changes in the Biological Condition of Lakes With Changes in Trophic State
R.E. Carlson
TSI < 30 Classical oligotrophy: Clear water, oxygen throughout the year in hypolimnion,
salmonid fisheries in deep lakes.
TSI 30 – 40 Deeper lakes still exhibit classical oligotrophy, but some shallower lakes will
become anoxic in the hypolimnion during the summer.
TSI 40 – 50 Water moderately clear, but increasing probability of anoxia in hypolimnion during
summer.
TSI 50 – 60 Lower boundary of classical eutrophy: Decreased transparency, anoxic hypolimnia
during the summer, macrophyte problems evident, warm-water fisheries only.
TSI 60 – 70 Dominance of blue-green algae, algal scums probable, extensive macrophyte
problems.
TSI 70 – 80 Heavy algal blooms possible throughout the summer, dense macrophyte beds, but
extent limited by light penetration. Often would be classified as hypertrophic..
TSI > 80 Algal scums, summer fish kills, few macrophytes, dominance of rough fish.
Water quality benchmarks based on ecoregion
Ecoregion Reference Lakes – One means for placing lake water quality information in perspective is to
compare summer mean values to those found in reference lakes from the same ecoregion in which the lake is
located in. Ecoregions were mapped for the United States from information on soils, landform, potential
natural vegetation, -and land use by the U.S. Environmental Protection Agency. For Minnesota, within-region
similarities in terms of quality and lake morphometric characteristics have been noted. Reference lakes,
deemed to be representative and minimally impacted by man (e.g., no point source wastewater discharges, no
large urban areas in the watershed, etc.) were sampled in each ecoregion by the MPCA from 1985 through
1988. The reference lake data base consists of approximately 90 lakes distributed as follows among the four
ecoregions with the majority of Minnesota’s lakes: Northern Lakes and Forests – 30, North Central Hardwood
Forest – 38, Western Corn Belt Plains – 12, and Northern Glaciated Plains – 10. Data from the reference lakes
can be used as a “yardstick” to compare other data against. Table I provides a range of summer mean values
for each parameter and each ecoregion. These values were taken from the “inter-quartile range” (25th to 75th
percentile) of the reference lakes for each region. By using these values, we have excluded the very low
values (lower 25 percent) and the very high values (upper 25 percent) and thus, have a range of values which
represent the central tendency of the reference lake’s water quality. If your lake is near the transition zone of
two ecoregions is often useful to make comparisons to reference lakes from both ecoregions.
Fish Community Structure Graphs
Relative fishery abundance (vertical axis) versus
lake water quality TSI (horizontal axis)
Minnesota Lake Phosphorus Criteria Development- Because of regional diversity in lake and watershed
characteristics, it was unlikely that a single total phosphorus value could be adopted as a statewide criterion
for lake protection in Minnesota (Heiskary et al. 1987). Rather, a methodology was needed for developing
lake water quality criteria on a regional or lake-specific basis.
The methodology for establishing lake water quality criteria in Minnesota considered the following (from
Heiskary and Walker, 1988):
1. phosphorus impacts on lake condition (as measured by chlorophyll a, bloom frequency, transparency,
and hypolimnetic oxygen depletion;
2. impacts on lake user (aesthetics, recreation, fisheries, water supply, etc.); and
3. attainability (as related to watershed characteristics, regional phosphorus export values, lake
morphometry, etc.).
Previous papers (Heiskary et al. 1987) have described the range in the trophic status of lakes in Minnesota
and the utility of the ecoregion framework in explaining some of this variability. Ecoregion maps, as
developed by EPA ERL-Corvallis, are based on land use, soils, land form, and potential natural vegetation
(Omernik, 1987). Recognizing patterns in lake trophic status between these regions has permitted the
development of some generalized lake management strategies (Heiskary and Wilson, 1988).
Minnesota is characterized by seven ecoregions (Figure 1). However, over 98 percent of Minnesota’s lakes
are found in four of the state’s seven ecoregions (Heiskary et al. 1987). Typical land use varies from the
forests in the north to the primary cultivated land and pastures to the south. A more detailed presentation of
the information may be found in Heiskary and Wilson (1988 and 1990).
The ecoregion framework provides a regional perspective on the uses of lakes in each part of the state and
allows for the definition of “most sensitive uses” in each region. The MPCA has defined the “most sensitive
use” of a lake as that use (or uses) which can be affected or even lost as a result of an increase in the trophic
status of the lake. Two examples include drinking water supplies and cold water fisheries. In the case of
drinking water supplies, eutrophication can increase water treatment costs (Walker, 1985), contribute to taste
and odor problems (Walker, 1985), and increase production of trihalornethanes during the treatment process
(Palmstrom et al. 1988). In a cold water fishery, increased nutrient loading will reduce oxygen in the
hypolimnion (Walker, 1979), and cold water species may die off as these populations are driven into warmer
surface waters (Colby and Brooke, 1969).
Table 2 presents some of the most sensitive lake uses for each ecoregion. Lakes corresponding to some of
these categories have been specifically identified in Minn. R. ch. 7050.0470, subp. 1-8 (1980), and include
designations for the following:
1. Domestic consumption (as defined in Chapter 7050.0220, subp. 2.1); and
2. Fisheries and recreation (as defined in Chapter 7050.0220, subp. 3.2), whereby Class A specifically
refers to waters designated for the propagation and maintenance of warm or cold water fish, with lake
trout lakes specifically identified in Chapter 7050.0420.
Once uses have been defined for a lake, in a given region, appropriate management strategies may be
developed. The management strategy for maintaining a given use (phosphorus goal) may vary between
regions and should reflect user expectations and regional variations in attainable lake trophic state.
For example, drinking water supplies in the Northern Lakes and Forests ecoregion are typically characterized
as oligotrophic to mesotrophic in nature. The cost of treating these waters to produce potable water is much
less than water obtained from eutrophic lakes in central and southern Minnesota. These treatments have
included extensive in-lake application of copper sulfate to reduce algal blooms and the use of potassium
permanganate and activated carbon in the treatment plants to reduce taste and odor (Walker, 1985; Hanson
and Stefan, 1984). Even with these treatments, taste and odor complaints are common among users of these
water supplies. Management strategies for water supplies should focus on decreasing the frequency and
intensity of algal blooms.
Regional patterns and user perceptions must be considered when managing lakes for primary contact
recreation and aesthetics. For example, a lake in the Western Corn Belt Plains ecoregion with Secchi
transparency in the 1.5 to 2.0 meter range would be considered to have only “minor aesthetic problems”, and
would support swimming. In contrast, a lake in the Northern Lakes and Forests ecoregion with this
transparency range would be deemed “swimming im-paired.” Using this information in conjunction with
regional patterns in lake trophic state, morphometry, and so forth, appropriate phosphorus management goals
may be set. For the Northern Lakes and Forests, an appropriate phosphorus goal to fully support swimmable
uses would be less than 30 μg/L, while in the Western Corn Belt Plains a phosphorus goal of 40 μg/L would
be required. However, only a few lakes in the WCBP can achieve a phosphorus concentration less than 40
μg/L and thus, a more reasonable goal may be “partial support” of swimmable use which corresponds to a
phosphorus concentration less than 90 μg/L.
The phosphorus criteria provide a basis for goal setting and prioritization. For example, lakes currently at or
below the criteria for their ecoregion will typically support the specified use. These lakes should be protected
from increases in phosphorus concentration, beyond natural variability, since even small increases in
phosphorus concentration can lead to increased algae blooms and decreased transparency in these lakes. In
most cases, these changes will be measurable and noticeable to long-time users of the resource. For those
lakes above the criteria, the criteria can serve as goals for restoration. In fact, the recently revised Clean
Water Partnership rule (Ch. 7 076.0240 Subp. 4c) notes for lakes in the CWP Program …’for lakes, an in-lake
phosphorus goal defined relative to the ecoregion phosphorus criteria.” In this case, the phosphorus criteria
become the cornerstone for setting goals in these projects. This does not mean that the goals are simply
applied as written, but goals are developed through the Phase I process and in conjunction with local steering
committees. This work is done in an ecoregion context and goals are set accordingly.
Table 3. Minnesota Lake Phosphorus Criteria (Heiskary and Wilson, 1988).
