Canadian Manuscript Report of Fisheries and Aquatic Sciences 2236 1994 ONTARIO GUIDELINES FOR

Canadian Manuscript Report of Fisheries and Aquatic Sciences 2236 1994 ONTARIO GUIDELINES FOR
Canadian Manuscript Report of
Fisheries and Aquatic Sciences 2236
1994
ONTARIO GUIDELINES FOR
AQUATIC PLANT CONTROL
by
Aquatic Ecosystems Branch
Ontario Ministry of Natural Resources
P.O. Box 7000
Peterborough, Ontario
K9J 8M5
and
Fisheries and Habitat Management Branch
Central and Arctic Region
Department of Fisheries and Oceans
P.O. Box 5050
Burlington, Ontario
L7R 4A6
c. Minister of Supply and Services Canada 1994
Cat. No. FS 97-4/2236EISSN 0706-6473
Correct citation for this publication:
Department of Fisheries and Oceans and Ontario Ministry of Natural Resources. 1994.
Ontario Guidelines for Aquatic Plant Control. Can. Manuscr. Rep. Fish.Aquat.Sci.
2236: 25 p.
TABLE OF CONTENTS
Page
Abstract/Resume
v
Acknowledgements
vi
1.1
Introduction
1
1.2
Fisheries Management Objectives
2
1.3
Legal Responsibilities
2
1.4
Purpose
3
1.5
Procedural Guidelines
4
1.5.1 General
4
1.5.2 Chemical Methods
4
1.5.3 Physical/Mechanical Methods
5
Technical Guidelines
6
6.1
General
6
6.2
Indentification of Fish Habitat
7
6.3
Timing
7
6.4
Size and Configuration of Treated Areas
8
6.4.1 Examples
9
A.
B.
C.
D.
10
10
11
12
6.0
Individual Properties
Commercial Establishments
Navigation Channels
Private Ponds
Page
6.5
Methods
13
6.5.1 Acceptability of Aquatic Plant Control Methods
14
6.6
Equipment
15
6.7
Use of Cut Vegetation
15
7.0
Monitoring
16
8.0
Procedural Summary
16
Literature Cited
18
Appendix
20
LIST OF FIGURES
Page
Figure 1. Boat Channel for a Single Property
11
Figure 2. Community Boat Channel for up to Five Properties
12
ABSTRACT
Department of Fisheries and Oceans and Ontario Ministry of Natural Resources. 1994.
Ontario Guidelines for Aquatic Plant Control. Can. Manuscr. Rep. Fish.Aquat.Sci.
2236: 25 p.
Aquatic plants play a key role in maintaining the biological productivity of healthy aquatic
ecosystems and are an important component of fish habitat. In southern Ontario,
particularly, many waters now contain excessive plant growth. As a result, limited control
of aquatic plants for recreational purposes may be appropriate. Such control must be
carried out so as to protect fish habitat and sustain Ontario’s aquatic resources. This
report presents procedural and technical guidelines designed to provide for a rational and
consistent approach to the review of public proposals for aquatic plant control. Among
the factors considered are the identification of fish habitat, methods of aquatic plant
control, equipment, timing, and the size and configuration of treated areas. The
document is intended primarily for the use of staff of the Ontario Ministry of Natural
Resources and of Fisheries and Oceans Canada who review public proposals for aquatic
plant control in Ontario.
RÉSUMÉ
Department of Fisheries and Oceans and Ontario Ministry of Natural Resources. 1994.
Ontario Guidelines for Aquatic Plant Control. Can. Manuscr. Rep. Fish.Aquat.Sci.
2236: 25 p.
Les plantes aquatiques ont une fonction essentielle dans le maintien de la bioproductivtié
des écosytèmes aquatiques en bon état; elles sont aussi une composante importante de
l’habitat du poisson. Dans le sud de l’Ontario, notamment, beaucoup de plans et de
cours d’eau sont envahis par les plantes. C’est pourquoui un contrôle limité des plantes
aquatiques à des fins récréative pourrait être justifié. Ce contrôle doit être fait avec le
souci de protéger l’habitat du poisson et d’assurer le maintien des resources aquatiques
de l’Ontario. On trouvera dans ce rapport des directives techniques et prodédurières
visant à établir une approche uniforme et rationnelle à l’examen des projets publics de
contrôle des plantes aquatiques.
Les facteurs considérés sont notamment la
détermination des habitats du poisson, les méthods de contrôle des plantes aquatiques,
l’équipment, les calendriers ainsi que la superficie et la configuration des surfaces
traitées. Ce document est destiné avant tout au personnel du ministère des Resources
naturelles de l’Ontario et de Pêches et Océans Canada qui font l’examen des projets de
contrôle des plantes aquatiques en Ontario.
v
Acknowledgements
These guidelines were prepared with the collaboration of many people. The primary
author was John Allin of Aquatic Ecosystems Branch, Ministry of Natural Resources.
Numerous staff of the Ministry provided advice and assistance. In particular, David Bell,
Lindsay Penney and Henk Rietveld contributed many useful ideas and suggestions.
Serge Metikosh of the Department of Fisheries and Oceans also reviewed the guidelines
during their development and offered advice and ideas. In addition, assistance was
provided by John Onderdonk and Geoff Carpentier of the Ministry of the Environment and
Energy and by Wayne Mitchell and Jim Norris of the Canadian Parks Service.
The guidelines were also reviewed by a number of non-governmental organizations
having an interest in matters of aquatic plant control. These included the Federation of
Ontario Cottagers’ Long Lake Milfoil Action Committee, the Ontario Federation of Anglers
and Hunters, the Ontario Marina Operators Association, Resorts Ontario, and South Bay
Stoney Lake Cottagers.
The helpful advice and assistance provided by all who reviewed the guidelines during
their development are gratefully acknowledged.
vi
1.0
INTRODUCTION
Aquatic plants are a natural part of healthy aquatic ecosystems. They play a key role in
maintaining the biological productivity of these systems by fixing energy available from
sunlight and making it available to other parts of the food web. Without aquatic plants,
lakes and streams would lose much of their ability to sustain life.
Aquatic plants are of two main types: algae, which may be single-celled or multi-celled;
and aquatic macrophytes (vascular plants) which generally possess true leaves, stems
and root systems (MOEE 1994, Bix and Schierup 1989). Macrophytes can be
catergorized as submergent (stems and leaves below the water surface), emergent
(much of the stem above the water surface), and floating-leaved (rooted or free-floating).
Aquatic plants provide many benefits. Macrophytes in particular are an important
component of fish habitat, providing spawning, nursery and feeding areas for many
species (Janecek 1988, Keast et al. 1978, Werner et al. 1983). They also provide
essential habitat for many species of wildlife, including food, nesting sites and protective
cover for waterfowl. Rooted aquatic plants also act to stabilize shorelines and lake
bottoms. This helps maintain water quality by reducing erosion and turbidity.
Some waters contain too much aquatic plants. In southern Ontario many waters now
contain excessive plant growth, reaching amounts which are detrimental both to healthy
aquatic communities and to recreational use. Most waters in northern Ontario and on the
Canadian Shield do not suffer from this problem, although there are exceptions.
The development of algal “blooms” or dense growths of macrophytes can lead to levels of
dissolved oxygen which are too low to support aquatic life. In addition, decomposition of
these plants releases nutrients to feed future plant growth and perpetuate the problem.
Dense plant growth can also severely impair boating, swimming, fishing and other
recreational uses.
Increased plant growth often occurs over very long periods of time as a result of the
natural aging process of a lake. It is therefore part of an ecological cycle and should be
recognized as such. However, plant growth is often accelerated by human activites
occurring in the watershed. Addition of nutrients through shoreline development, lot
clearing use of lawn fertilizers and high-phosphate dishwashing detergents, and
agricultural runoff contributes to the excessive growth of aquatic plants.
In some Ontario lakes Eurasian water milfoil, an introduced plant species, has largely
displaced native plants. In other waters milfoil has invaded areas which had for the most
part been unvegetated. In both cases dense growths of milfoil now cover large areas of
many of these waters.
The control of nutrient and sediment inputs to surface waters generally provides the best
1
long-term protection against excessive aquatic plant growth. Where heavy plant growth
already exists, limited aquatic plant control for recreational purposes may be appropriate.
2.0
FISHERIES MANAGEMENT OBJECTIVES
In Ontario, the Ministry of Natural Resources (MNR) and the Department of Fisheries and
Oceans (DFO) share responsibility for the management of fisheries resources. In
meeting this responsibility, the two agencies are guided by direction contained in the
Strategic Plan for Ontario Fisheries (SPOF) and the DFO Policy for the Management of
Fish Habitat (DFO 1986). SPOF identified the loss of fish habitat as one of the major
issues facing Ontario fisheries (MNR 1990a).
An important factor in the loss of fish habitat has been poorly planned shoreline
development. In many cases, physical alterations of the shoreline have led to a reduction
in the capacity of the waterbody to support a heathly fishery. The control of aquatic
plants can have a major impact on nearshore habitat.
MNR, in meeting its obligations under the Canada-Ontario Fisheries Agreement (1988), is
committed to ensuring there is “no net loss” of habitat. In the case of aquatic plants, any
proposal for plant control must be carefully reviewed to ensure that the project will not
result in a net loss of habitat.
Limited removal of plants, particularly in waters containing heavy plant growth, may
benefit fish by increasing edge and habitat diversity. For example, the presence of open
water adjacent to vegetated areas improves feeding efficiency for certain size classes of
some fish species (Mittelbach 1981). Feeding efficiency and growth rates may also
increase with a reduction in plant density (Gotceitas 1990, Crowder and Cooper 1982). In
addition, partial removal of plants in areas of dense vegetation provides better access to
inshore areas for large fish as well as anglers (Engel 1985, Killgore et al. 1989).
The Ministry understands the desire for water-based recreation and recognizes that
people are an integral part of aquatic ecosystems. However, MNR must also ensure that
all activities are carried out so as to protect fish habitat and sustain Ontario’s aquatic
resources. In developing these guidelines, the Ministry has tried to strike a reasonable
balance between the need to sustain healthy aquatic ecosystems and the public’s desire
for recreational opportunities.
3.0
LEGAL RESPONSIBILITIES
The Fisheries Act (Canada) prohibits the harmful alteration, distruption or destruction of
fish habitat. Fish habitat is defined in the Act as “spawning grounds and nursery, rearing,
food supply and migration areas on which fish depend directly or indirectly in order to
2
carry out their life processes”. MNR is responsible for administering the Act in Ontario
and is commited to ensuring “no net loss” of habitat.
Persons proposing to remove aquatic plants must also comply with other federal,
provincial and municipal legislation. Anyone proposing to apply a herbicide for the control
of aquatic plants must first obtain a permit issued by the Ministry of Environment and
Energy (MOEE) under the Pesticides Act (Ontario).
The Public Lands Act (Ontario) prohibits the clearing of public lands without a valid work
permit issued by MNR. The beds of most waterbodies in Ontario are public lands which
belong to the province. The physical or mechanical removal of aquatic plants on such
lands has been determined to fall within the definition of “clearing”. Therefore, MNR may
require persons proposing to carry out aquatic plant control by physical means to obtain a
work permit. No permit from MOEE is required for plant control by physical or mechanical
means.
Where aquatic plants grow on federal lands, such as most of the Trent-Severn and
Rideau waterways, plant control activities must be authorized by the appropriate federal
agency (e.g. Canadian Parks Service).
Other legislation may also apply to the control of aquatic plants. For example, disturbing
or destroying nests or eggs of migratory birds is prohibited under the Migratory Birds
Convention Act (Canada). Destroying or interfering with the habitats of endangered
species is prohibited under the Endangered Species Act (Ontario). Further, persons
removing aquatic plants by physical or mechanical means must remove cut vegetation
from the water. Failure to do so can result in prosecution under the Water Resources Act
(Ontario) or the Environmental Protection Act (Ontario).
4.0
PURPOSE
The purpose of these guidelines is to provide for a rational and consistent approach by
Ministry staff in reviewing public proposals for aquatic plant control.
Use of the guidelines will ensure that the Ministry’s review is consistent with its fisheries
management objectives and responsibilities. The guidelines are not intended to provide
comprehensive direction concerning other Ministry objectives (e.g. management of
wildlife habitat). However, in reviewing proposals for aquatic plant control, Ministry staff
should have regard for related objectives such as the protection of provincially significant
wetlands.
Guidelines cannot be written to address all possible situations to which they might be
applied. These guidelines should therefore be used with some flexibility, bearing in mind
local conditions and circumstances. However, use of the guidelines must always be
3
consistent with fulfilling the Ministry’s responsibilities for fisheries management.
5.0
PROCEDURAL GUIDELINES
5.1
General
In view of the benefits provided by aquatic plants, the need for plant removal should
always be evaluated carefully. In some cases the public may choose not to remove
vegetation if they are made aware of the disadvantages of plant control (see Section 1.0
and Appendix 1). In other cases removal of aquatic plants may benefit both aquatic
communities and recreational use. Each case should be assessed on its own merits.
Review of individual proposals for aquatic plant control must also involve a consideration
of shoreline developments elsewhere on the same waterbody. The potential cumulative
effects of all shoreline aterations, including plant control activities, must be assessed.
Consequently, persons wishing to control aquatic plants should be advised to apply for
permission early to allow proposals to be reviewed on a whole-lake basis. Applicants
should also be cautioned that many similar applications may be received and that a site
inspection during the open water season may be required (MNR-DFO, 1993). To allow
the necessary time for processing, it is recommended that applications be made to the
appropriate agency (see Sections 5.2 and 5.3 by April 1 of the year in which the proposed
activity would be carried out.
5.2
Chemical Methods
The use of chemical pesticides (herbicides) to control aquatic plants is regulated by the
Ministry of Environment and Energy through a licence and permit system under the
authority of the Pesticides Act. Applications for herbicide permits should be made to
MOEE, which then forwards them to the appropriate MNR district for review. On federal
lands MOEE also ensures that the appropriate federal agency (e.g. Canadian Parks
Service) has an opportunity to review all applications.
To avoid requiring an applicant to obtain another permit (i.e. a work permit as well), MNR
district staff should impose any conditions on the project during their review of the
application for a herbicide permit.
Conditions which MNR managers intend to apply commonly to permits should be
discussed with MOEE at an early stage so that when permits are received, review by
MNR can be expedited. In cases where MNR refuses to approve a project or attaches
conditions to its approval, MNR must provide a written statement to MOEE explaining the
basis for refusal or for the conditions imposed. Under the Pesticides Act, applicants have
4
the right to appeal refusal of the project or any conditions placed on it. Managers should
therefore be prepared to defend their decision at a hearing before the Environmental
Appeal Board.
Although it is MOEE’s responsibility to calculate the amount of herbicide required for a
project, when imposing permit conditions such as size of treatment area, MNR managers
should take into consideration the quantity of herbicide required. The minimum quantity
of Reglone A that can be bought is a 1 litre container. This amount normally treats an
area of approximately 460 square metres (5000 square feet). Where possible, the size of
treatment area should be selected so as to avoid the need to store small leftover
quantities of herbicide (e.g. <0.2 litres). Larger amounts of leftover chemicals should be
saved for future use.
5.3
Physical /Mechanical Methods
For projects involving physical or mechanical control of aquatic plants located on
provincial Crown land (see Section 6.5.1 for a partial list of methods), proponents (or the
contractor who would do the work) may be required to obtain a work permit. This permit
is issued by MNR under the Public Lands Act. A work permit is not required for projects
on privately owned shorelands unless the proposal involves dredging or filling.
Where a work permit is required, applicants should be required to provide the following
information for all plant control projects:
ƒ name of lake/stream
ƒ a map identifying the location of the property in relation to
neighbouring properties and main roads and indicating the names of
adjacent landowners
ƒ a sketch of the project area showing:
•
•
•
•
•
•
the lot sidelines of the property
the length of frontage (in metres)
the location of docks or other structures on the shoreline
the location of aquatic plants adjacent to the property
the location of aquatic plants proposed for removal and
approximate size of area (in square metres)
the location of any areas in which fill has previously been
placed on the bottom for beach creation
5
ƒ the type of aquatic plants proposed for removal (emergent,
submergent, or floating)
ƒ predominant type of lake/stream bottom in areas of plants proposed
for removal (mud, sand, gravel or other)
ƒ purpose of plant control (e.g. swimming, boat access)
ƒ proposed method of plant removal (e.g. hand removal, mechanical
harvester)
ƒ proposed location and method of disposal of harvested plants.
The above information requirements are in addition to any others required by MNR staff
to carry out their responsibilities. Some of the information may have to be provided as an
attachment to the work permit application form (if a permit is required).
If available, copies of appropriate low-level aerial photographs of shoreline areas can be
provided to applicants to help them identify the project area. Alternatively, the applicant
may wish to provide a photograph or videotape of the shoreline, taken in mid-summer, to
illustrate the details of the proposed project. This may avoid the need for a site inspection
and speed up the review process.
In cases where aquatic plants are located on federal lands, authorization for plant control
activities must be obtained from the appropriate federal authority (e.g. Canadian Parks
Service). In some cases MNR carries out the review of proposals on behalf of the
Canadian Parks Service through local agreements between the two agencies.
6.0
TECHNICAL GUIDELINES
6.1
General
The acceptability of aquatic plant control in a given situation depends on many factors.
Specific recreational needs and the effectiveness of plant control in meeting those needs
are clearly important factors. However, the requirements to maintain a healthy aquatic
ecosystem and to protect fish habitat, in particular, dictate that many other factors be
considered.
Among the factors of importance to fish habitat are the species composition of both plants
and fish in the waterbody in question. Exotic (non-native) plant species such as Eurasian
water milfoil tend to crowd out native species and may provide less diverse and
productive habitat than does a mixture of native species (Keast 1984, Smith and Barko
6
1990). Nevertheless, milfoil provides valuable habitat for some species of fish (Janecek
1988). It may increase fish production by providing habitat which did not exist previously
(Borowa et al. 1979). The acceptability of removing plants therefore depends on their
ecological value and the effects of removal, not whether they are native or exotic.
The habitat value of plants is also a function of the overall distribution and abundance of
both plants and fish in a given waterbody. For example, plants of potential importance as
nursery habitat should be close to the spawning areas of fish species which need them.
Other things being equal, larger amounts of vegetation can be removed without resulting
in loss of fish habitat where plants are abundant than where they are scarce. Where plant
growth is very limited, as is typical of nutrient-poor lakes on the Canadian Shield, any
plant removal may be unacceptable.
Whatever the circumstances, the control of aquatic plants should always be viewed from
an ecological perspective, with full consideration of the benefits of plants to local
ecosystems.
6.2
Identification of Fish Habitat
Ministry staff should make every effort to identify and document the location of important
fish habitat in the vicinity of areas proposed for treatment. Particular attention should be
paid to the quality and quantity of spawning, nursery and feeding areas which could be
affected by the treatment.
Special consideration should also be given to habitat types provided by plant species
believed to be in limited supply in the waterbody in question. For example, wetland areas
should be identified and their value as fish habitat documented.
In some cases man-made areas such as boat channels and dock areas provide fish
habitat which did not exist previously. Fish habitat in these areas must be protected to
the same degree as habitat of natural origin.
6.3
Timing
Warmwater fish species require the spring and early summer period for spawning and
early rearing activities. Removal of aquatic plants during this period may result in
mortality to eggs and fry, and may disrupt the food web, thereby affecting young fish in
particular.
In waters supporting warmwater fish communities, plant control should generally be
prohibited until spawning and early rearing periods are complete. However, both the
timing of local plant growth problems and the effectiveness of proposed control operations
7
must also be considered. For example, chemical control of Eurasian milfoil may not be
very effective if carried out after July 1. Also, in southern Ontario purple loosestrife
usually flowers and sets seed in August. The best time to remove loosestrife plants is
when they are in flower, and therefore easily identified, but before they set seed.
In some cases the selective removal of dense plant growth in early spring to provide boat
access in early summer (June) may precede fish spawning. Decisions as to the timing of
control activities should therefore involve a consideration of the species of plants to be
removed, the timing of plant growth problems, the fish community, and prevailing weather
conditions. Regions should consider developing criteria for timing restrictions which are
appropriate to local situations.
6.4
Size and Configuration of Treated Areas
It is impossible to specify criteria for determining acceptable plant control activities in all
situations. However, some activities should not be permitted, either because they are
likely to contravene legislation or Ministry policy, or because they may interfere with the
proprietary rights of some other person. The following activities should not be permitted:
ƒ removal of rare, threatened or endangered plant species (MNR 1994)
ƒ removal of plants required during any life stage of vulnerable,
threatened or endangered fish species (MNR 1991)
ƒ removal of plants from areas containing the nests of migratory birds;
removal after the nesting season may be acceptable
ƒ treatment of areas outside the straight line extension of lot sidelines
(except for boat channels; lot configuration should also be
considered)
ƒ treatment of areas beyond the centreline of rivers and streams
ƒ harmful disruption of adjacent littoral areas
(e.g. movement of
sediment into adjacent areas)
In addition, certain activities should generally not be permitted because they are likely to
have adverse effects on the environment, including local resources. The following
activities should generally not be permitted:
ƒ removal of significant wild rice stands
8
ƒ complete removal of large blocks of aquatic vegetation (for details
see Section 6.4.1 A)
ƒ control of aquatic plants by methods judged unacceptable in these
guidelines (see Section 6.5.1)
In general, the removal of plants should be kept to the minimum necessary to meet
recreational needs (e.g. providing boat access or a swimming area) as opposed to
removal for aesthetic reasons.
In areas of heavy plant growth, boat channels accessing individual properties should
generally be oriented perpendicular to the shoreline and should not exceed 6 metres in
width. Boat channels serving a number of properties may need to be wider (see Section
6.4.1 A). Creation of a swimming area should not normally require clearing an area larger
than 60 square metres (e.g. 6 m x 10 m).
Where plant growth is extensive, many landowners may wish to remove plants fronting
their property. In order to prevent the removal of large blocks of vegetation, it may be
necessary to impose a limit on the proportion of each landowner's frontage in which the
growth of plants may be controlled. Such a limit should reflect a judgement as to the
potential cumulative effect on fish habitat of all proposed projects on the waterbody in
question. Examples of maximum limits are given in Section 6.4.1 A.
Removal of aquatic plants on a large scale, such as across entire frontages or bays,
would invariably result in a loss of fish habitat and must not be permission.
6.4.1 Examples
It is impossible to describe acceptable plant control activities in every type of situation that
might occur. However, indicated below are some examples of common situations
together with some guidelines in determining permissible levels of plant control.
The guidelines provided in this section are intended to apply to waters with heavy plant
growth, as in many ears of the Trent-Severn and Rideau systems. Consequently, they
represent maximum levels of plant control which may be appropriate in waters which
contain extensive plant growth. They are not intended to apply to waters in which plant
growth is limited, such as most waters on the Canadian Shield. The acceptability of plant
control activities under conditions of limited plant growth must be determined on a sitespecific basis.
Wherever possible, acceptable levels of plant control should be determined on the basis
of local knowledge, conditions and experience.
9
A.
Individual Properties
In waters with extensive plant growth, the area in which plant control is permitted for
individual properties should generally be based on the frontage of each property.
Recommended limits for plant control are as follows:
FRONTAGE
OF PROPERTY
MAX. WIDTH
OF REMOVAL
MAX. DISTANCE
OFFHSORE
MAX. WIDTH
BOAT CHANNEL
> 22 m
15 m
30 m
6m
< 22 m
8m
30 m
6m
The limits recommended here are designed to prevent removal of large blocks of
vegetation while still permitting a reasonable amount of plant control by each property
owner. In addition, the creation of alternating areas of vegetation and open water creates
increased edge and increases fish habitat diversity.
These limits represent maximum areas in which plant control should be permitted. In
many cases the treated area need not be as large as indicated here. However, in waters
with heavy plant growth the potential ecological benefits of plant control should always be
considered.
The boat channels referred to above are those serving individual properties. Boat
channels are not included in the main treated areas described above (i.e. maximum 15
x 30 m or 8 x 30 m). They are calculated separately. However, if possible, boat
channels should back on to the main treated area so as not to increase the frontage
treated (see Figure 1). Boat channels can be as long as necessary in order to reach
open water.
Where server adjacent properties are to be treated, a single boat channel can be shared
among property owners. A general rule of thumb is one channel for every 5 properties
(see Figure 2). For safety reasons these “community” channels usually need to be wider
than those serving individual properties. However, they seldom must be wider than 8 m.
B.
Commercial Establishments
Extensive plant growth in the vicinity of commercial establishments (e.g. resorts, marinas)
may restrict recreational opportunities for many people who depend on these
establishments for water-based recreation. The ability to provide recreational and other
benefits from nearshore areas may also seriously affect people’s livelihoods.
Consequently, there is a need to be particularly flexible in determining the timing and
amount of plant control permitted.
10
Figure 1: Boat Channel for a Single Property.
Where these establishments are concerned, permissible plant control activities must be
determined on a case by case basis. As a general rule, in the case of lakeshore resorts
only areas around beaches and those required for boating need be subject to plant
control. The use of a common area for swimming should be encouraged. Large areas or
bays should not be cleared of plants purely on the basis of aesthetic concerns.
C.
Navigation Channels
In some waters it may be necessary to remove plants in navigation channels. AThis
typically involves clearing channels sufficiently large for the safe movement of large
boats. Many of these channels are located primarily offshore in deeper portions of the
waterbody. Since the clearing of such channels is usually only required in waters
containing very extensive plant growth, removal of aquatic plants in these deep channels
will generally have a limited effect on fish habitat.
11
Figure 2: Community Boat Channel for up to Five Properties
Given the potential impact of aquatic plants on navigation channels and the generally
limited effect of plant removal on fish habitat, a good deal of flexibility is needed in
determining permissible plant control activities for navigation purposes. However, plant
removal should generally be confined to buoyed areas or navigation channels as
designated by the appropriate authority.
Where physical or mechanical control methods are used, cut vegetation must be removed
from the water.
D.
Private Ponds
The Fisheries Act applies to private as well as Crown waters. Proposals for aquatic plant
control in private ponds should therefore be reviewed by MNR for their potential impact on
fish and fish habitat. However, unless a pond discharges to Crown waters, the Ministry
will generally have little or no concern about such projects.
12
Where a private pond discharges to Crown waters and the inflow and outflow cannot be
shut off during treatment, the potential effect of plant control activities on fish habitat in
receiving waters must be assessed. Although work permits are not required under the
Public Lands Act for private ponds, proposals should be reviewed using the “Interim
Referral Process for Authorization of Fish Habitat Alterations, Disruption, Destruction –
Section 35 (2) of the Fisheries Act”.
6.5
Methods
Physical or mechanical methods of aquatic plant control generally involve the removal of
vegetation by hand or through the use of various mechanical devices. Chemical plant
control involves the use of herbicides. All herbicides used must be federally registered for
aquatic plant control and be approved for use in Ontario by MOEE (MOEE 1994).
No one method of pant control is best in all situations. All methods have advantages and
disadvantages with respect to such factors as environmental effects, effectiveness, cost,
availability and ease of use (MOEE 1994).
Both chemical and physical/mechanical control methods may have negative
environmental effects unless projects are carefully planned and carried out. If used
improperly, herbicides may pose problems of toxicity to other aquatic life. Also, water
quality may be impaired through oxygen depletion if large amounts of dead vegetation are
left to decompose. Physical or mechanical methods may disturb bottom sediments and
impair water quality if cut plants are left in the water. Such methods may also encourage
spreading of plants through fragmentation (e.g. Eurasion water milfoil). Any method of
plant control may potentially destroy fish habitat. Careful consideration must therefore be
given to the use of various methods in a particular situation.
In some cases it is illegal to use chemical control methods. For example, the use of
herbicide to kill purple loosestrife in aquatic environments is not permitted. The best
method of removing loosestrife is to pull out the entire plant, including the root, by hand.
Some of the advantages and disadvantages of various control methods are summarized
in Appendix 1. An assessment of the general acceptability of each method from an
environmental perspective is also given. Judgements of acceptability assume that
direction contained in these guidelines is followed and that, in particular, measures are
taken to protect important fish habitat such as spawning and nursery areas.
General conclusions as to the acceptability of various methods are indicated below.
13
6.5.1 Acceptability of Aquatic Plant Control Methods
Physical/Mechanical Methods
(a)
Hand Removal
Generally Acceptable, provided pulled or
cut vegetation is removed from the water
(b)
Raking
Generally Acceptable, provided raked
vegetation is removed from the water
(c)
Chains or Harrows
Not Acceptable, because of bottom
disturbance and inability to collect loose
plant material
(d)
Cutter-bar Devices
Generally Acceptable, provided: (1) small
devices are used which limit the volume of
cut plant material produced, (2) bottom
disturbance is minimized, and (3) cut
vegetation is removed from the water
(e)
Mechanical Harvesting
Generally Acceptable, provided:(1) bottom
disturbance is minimized, and (2) cut
vegetation is removed from the water
(f)
Mechanical Derooting
Uncertain at this time; some devices may
be acceptable if cut and/or derooted
vegetation is removed from the water but
needs further evaluation
(g)
Dredging
Not Acceptable, except where removal of
sediment as well as plants is approved;
examples of where dredging may be
considered include:
14
ƒ
creation or maintenance of boat
channels or drainage ditches
ƒ
providing access for fish or
improving water circulation within
marshes
ƒ
providing increasing water storage
for flood control
(h)
Filling
Not Acceptable, except where addition of
fill is approved for other purposes (e.g.
beach creation)
(i)
Surface Films
Not Acceptable, because of limited
effectiveness and nuisance potential
(j)
Bottom Barriers
Generally Acceptable, provided: (1)
proper materials (opaque, durable, gas
permeable) are used, and (2) the barrier
is properly installed using adequate
weights or other devices
Chemical Methods
(a)
6.6
Herbicides
Generally Acceptable, provided all permit
and label conditions are complied with
Equipment
Use of equipment which will seriously disturb the bottom (e.g. chains, harrows) must not
be permitted. Similarly, draglines or suction dredges must not be used to remove aquatic
plants unless the removal of sediment is approved (see Section 6.5.1 (g), above).
Whatever equipment is used, proponents must be advised to remove cut plants from the
water.
Mechanical harvesting equipment must be properly maintained to avoid contamination of
water by spills or leakage of oil, gasoline and other petroleum products.
To avoid possible erosion and disruption of fish habitat, harvesting equipment should be
launched and removed at appropriate launching facilities, not from unprotected shoreline.
6.7
Use of Cut Vegetation
All cut or uprooted vegetation must be removed from the water to maintain water quality
and to avoid interference with other water users.
Where large quantities of vegetation are removed, they should be placed temporarily at a
suitable holding site, prior to use or disposal. The site should be sufficiently distant from
the shoreline to prevent leaching of nutrients back into the water.
Where quantities of cut vegetation are limited, they can generally be composted and used
15
as a soil conditioner or garden mulch. However, the flowers of purple loosestrife should
not be composted as the seeds may remain viable and result in the growth of new plants.
Loosestrife can also be spread by leaving plant fragments on land. The best method of
disposing of loosestrife is to burn all parts of these plants.
If plants cannot be used for beneficial purposes, the homeowner may dispose of them
with garden waste (e.g. leaves). However, if a contractor intends to remove vegetation
from the property to a disposal site, approval from MOEE for transport and disposal is
required.
7.0
MONITORING
Any fish kills are harmful alterations of fish habitat resulting from aquatic plant control
activities must be reported at once to MOEE or MNR.
MNR field offices should develop programs for monitoring compliance with conditions
imposed on activities involving the control of aquatic plants.
8.0
PROCEDURAL SUMMARY
STEP 1
The proponent seeks permission to control aquatic vegetation. To allow time
for processing of applications, requests should be submitted by April 1 of
the year in which the proposed activity would be carried out.
If the proponent wishes to use a herbicide, he or she must obtain a Permit
to Purchase and/or Perform a Water Extermination from MOEE. MOEE
provides the appropriate form and forwards the completed form to MNR for
review. If MNR refuses the project or attaches conditions, written reasons
must be provided to MOEE explaining the basis for the refusal or the
conditions imposed.
If the proponent wishes to use physical or mechanical methods of plant
control, only approval from MNR is normally required. However, approval
must be sought for all projects regardless of project size.
Plant control activities on federal lands must be authorized by the
appropriate federal agency (e.g. Canadian Parks Service).
STEP 2
MNR staff review the proposal. All proposals must be reviewed with respect
to their potential effects on fish habitat.
16
As with other forms of shoreline alteration, reviewers should refer to the
“Interim Referral Process For Authorization of Fish Habitat Alterations,
Disruption, Destruction – Section 35 (2) of the Fisheries Act”.
STEP 3
If the proposal is for the physical or mechanical control of aquatic plants, the
proponent (or contractor) may be required to obtain a work permit issued
under the authority of the Public Lands Act. The proponent must provide all
information required for proper review, as described in Section 5.3.
Appropriate terms and conditions can be stated on the permit.
In general, a permit should be required for all proposals which involve
contractors as well as those of a size or nature that warrant strict control.
A work permit is not required for projects on privately owned shorelands
(except where dredging or filling is involved), or for projects on private
ponds.
STEP 4
In waters with extensive plant growth, the local Ministry manager may
choose not to require authorization by a work permit if the proposed project
is small in size. For example, a cottager may whish to remove plants
around a dock or create a small wading or swimming area less than 60
square metres in area. If the proponent agrees to remove cut plants from
the water, the manager may authorize the project by a letter or other
means.
Whatever form of authorization is used, the approved activity and any
conditions of approval should be clearly specified.
17
LITERATURE CITED
Brix, H. and H. H. Schierup. 1989. The use of aquatic macrophytes in water pollution
control. Ambio 18(2): 100-107.
Crowder, L.B. and W.E. Cooper. 1982. Habitat structural complexity and the interaction
between bluegills and their prey. Ecology 63(6): 1802-1813.
Department of Fisheries and Oceans. 1986. The Department of Fisheries and Oceans
policy for the management of fish habitat. Department of Fisheries and Oceans.
Engel, S. 1985. Aquatic community interactions of submerged macrophytes. Tech. Bull.
No. 156, Wisconsin Department of Natural Resources, Madison, Wisconsin. 79 pp.
Gotceitas, V. 1990. Variation in plant stem density and its effects on foraging success of
juvenile bluegill sunfish. Environ. Biol. Fishes 27: 63-70.
Janecek, J.A. 1988. Literature review on fishes interactions with aquatic macrophytes
with special reference to the Upper Mississippi River System. Upper Mississippi River
Conservation Committee, Fisheries Section, Rock Island, Illinois. 57 pp.
Keast, A. 1984. The introduced aquatic macrophyte, Myriophyllum spicatum, as habitat
for fish and their invertebrate prey. Can. J. Zool. 62: 1289-1303.
Keast, A., J. Harker, and D. Turnbull. 1978. Nearshore fish habitat utilization and
species associations in Lake Opinicon (Ontario, Canada). Environ. Biol. Fishes 3(2); 173184.
Killgore, K.J., R. P Morgan II, and N. B. Rybicki. 1989. Distribution and abundance of
fishes associated with submersed aquatic plants in the Potomac River. North Amer. J.
Fish. Manage. 9: 101-111.
Ministry of Environment and Energy. 1994. Permits for aquatic plant control - applicant
information guide. Ontario Ministry of Environment and Energy.
Ministry of Natural Resources. 1990a. A revised strategic plan for Ontario fisheries - an
ecosystem approach. Fisheries Branch, Ontario Ministry of Natural Resources.
Ministry of Natural Resources. 1991. OMNR fish species tables - COSWEWIC
designations. Fisheries Policy Branch, Ontario Ministry of Natural Resources.
Ministry of Natural Resources. 1994. Rare, threatened, endangered, extirpated or extinct
species of Ontario.
Terrestrial Ecosystems Branch, Ontario Ministry of Natural
Resources.
18
Ministry of Natural Resources and Department of Fisheries and Oceans. 1993. Working
around water. Fact sheet, Ontario Ministry of Natural Resources.
Mittelbach, G. G. 1981. Foraging efficiency and body size: a study of optimal diet and
habitat use by bluegills. Ecology 62(5): 1370-1386.
Smith, C. S. And J. W. Barko. 1990. Ecology of Eurasian water milfoil. J. Aquat. Plant
Manage. 28: 55-64/
Werner, E. E., J. F. Gilliam, D. J. Hall, and G. G. Mittelbach. 1983. An experimental test
of the effects of predation risk on habitat use in fish. Ecology 64(6): 1540-1548.
19
APPENDIX
Some of the advantages and disadvantages of different methods of aquatic plant control
are indicated below. An assessment of the general acceptability of each method from an
environmental perspective is also given, assuming the present guidelines are followed.
Physical/Mechanical Methods
(a) Hand Removal
Pros
-
Cons
-
Acceptability
economical
simple to do
removes some plant roots, so may provide relatively
long-term control (1 year +)
allows treatment of small, nearshore areas
facilitates removal of plant material from water
non-toxic to aquatic life
labour-intensive
ineffective for clearing boat channels or moderate sized
swimming areas
may create minor turbidity
-
Generally Acceptable, provided pulled or cut vegetation
is removed from the water
Pros
-
same as for hand removal (above)
Cons
-
labour-intensive
ineffective for clearing boat channels
may create minor turbidity and release nutrients and
contaminants to the water
may destroy aquatic invertebrates
(b) Raking
Acceptability
-
Generally Acceptable, provided raked vegetation is
removed from the water.
20
(c) Chains or Harrows
Pros
-
Cons
-
Acceptability
removes some plant roots, so may provide relatively
long-germ control
non-toxic
causes major physical disturbance of the bottom
creates turbidity, and may release nutrients and
contaminants to the water
destroys aquatic invertebrates
doesn’t allow collection of plant material which may
move onto the property of others
-
Not Acceptable, because of bottom disturbance and
inability to collect loose plant material
Pros
-
allows treatment of small, nearshore areas
no physical disturbance of the bottom
non-toxic
Cons
-
provides only short-term control
ineffective for clearing boat channels
improper use pulls, instead of cutting, plants potentially
resulting in increased turbidity, and nutrient and
contaminant release
difficult to collect cut plant material
(d) Cutter-bar Devices
Acceptability
-
Generally Acceptable, provided: (1) small devices are
used which limit the volume of cut plant material
produced, (2) bottom disturbance is minimized, and (3)
cut vegetation is removed from the water.
Pros
-
removes cut plant material from the water
removes nutrients from the water (in cut vegetation)
non-toxic
Cons
-
relatively costly
(e) Mechanical Harvesters
21
-
Acceptability
-
provides only short-term control
availability of equipment may be limited
may be difficult to use in small, nearshore areas
difficult to use in shallow water containing obstructions
(e.g. logs, rocks)
may disturb bottom sediments in shallow waters
collects large volumes of plant material which require
proper disposal
removes invertebrates and small fish with the cut
vegetation
Generally Acceptable, provided: (1) bottom disturbance
is minimized, and (2) cut vegetation is removed from
the water
(f) Mechanical Derooting Devices
Pros
-
Cons
-
Acceptability
removes most plant roots so provides relatively long
term control ( 1 year +)
some devices can operate in relatively deep water (6
metres)
may rejuvenate gravel spawning beds by clearing away
plants and sediment
non-toxic
costly
causes physical disturbance of the bottom
creates turbidity, may release nutrients and
contaminants to the water
destroys aquatic invertebrates
may be difficult to use in shallow water containing
obstructions
may be difficult to collect cut plant material
-
Uncertain at this time; some devices may be acceptable
if cut and/or derooted vegetation is removed from the
water but needs further evaluation
-
removes plant roots so provides long term control if
dredging is sufficiently deep
(g) Dredging
Pros
22
-
may improve water circulation in heavily vegetated
areas (e.g. cattail marshes)
may improve access for fish to habitat within heavily
vegetated areas (e.g. marshes)
-
Cons
-
costly
causes major physical disturbance of the bottom
creates turbidity and releases nutrients and
contaminants to the water
destroys aquatic invertebrates
creates problems with disposal of dredged material,
particularly if contaminated
-
Acceptability
-
Not Acceptable, except were removal of sediment as
well as pants is approved. Examples of where dredging
may be considered include:
•
creation or maintenance of boat channels or
drainage ditches
•
providing access for fish or improving water
circulation within marshes
•
providing increased water storage for flood
control
(h) Filling
Pros
-
simple to do in shallow areas
provides immediate plant control
use of granular material may improve fish habitat
Cons
-
control may be short term if fill material washes away
or if plants grow on the fill
creates major physical disturbance of the bottom
creates turbidity
may release nutrients and contaminants to the water
unless clean fill is used
material may move into adjacent areas
may destroy spawning or nursery habitat
destroys aquatic invertebrates
Acceptability
-
Not Acceptable, except were addition of fill is
approved for other purposes (e.g. beach creation)
23
(i) Surface Films
Pros
-
simple to use
permits treatment of small, nearshore areas
non-toxic
Cons
-
effectiveness is limited since light can enter from the
sides
easily displaced by wind, waves, etc.
may cause littering of the shorelines
may interfere with boating and swimming
not aesthetically pleasing
Acceptability
-
Not Acceptable, because of limited effectiveness and
nuisance potential
(j) Bottom Barriers (Blankets or Mats)
Pros
-
Cons
-
Acceptability
-
provides effective, long term control (many years) if
proper materials are used (opaque, durable, gas
permeable)
permits treatment of small areas
non-toxic
may be costly, depending on material used and
installation requirements
requires removal of rocks, stumps, etc. prior to
installation
requires cleaning to prevent deposit of sediment on
top and subsequent regrowth of plants
may require installation and removal each year in
turbid waters
seals off the bottom and destroys invertebrates
Generally Accepted, provided: (1) proper materials
(opaque, durable, gas permeable) are used, and (2)
the barrier is properly installed using adequate
weights or other devices
24
Chemical Methods
(a) Herbicides
Pros
-
Cons
-
Acceptability
-
quick and economical
permits treatment of small, nearshore areas
control lasts one full season including period of heavy
recreational use
no physical disturbance of the bottom
use when plants are still small may minimize
dissolved oxygen depletion in the long term
not effective against all plant species
may not be effective for small, strip treatments in
heavy plant growth
effective for one season only
some concerns about toxicity to not-target species
leaves plant debris on the bottom
provides nutrients for plant regrowth
may reduce dissolved oxygen in the short term
Generally Acceptable, provided all permit and label
conditions are complied with
25
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