The two main water management problems in the Thames River basin
are water quality impairment and flooding. Impairment of surface
water quality is primarily caused by excessive inputs of nutrients,
oxygen consuming materials, bacteria and suspended solids. Major
urban sources of these contaminants include sewage treatment plant
effluent, storm and combined sewer discharges and runoff from urban
areas. Municipal drains, field tile systems, surface runoff from
fertilized fields, drainage from intensive feedlots, treated
effluent from rural industries, and the free access of cattle to
streams are major rural sources of water quality impairment.
Excessive aquatic plant growth and unpleasant aesthetic conditions
are the most visible signs of water quality impairment; however, the
less visible problems of low dissolved oxygen levels and high
bacteria levels are also significant. This impairment has led to the
curtailment or restriction of legitimate water uses in the
watershed. Most severely affected by this impairment are fish and
aquatic life and recreational water uses.
Recurrent flooding is the other most significant problem in the
watershed, particularly in St. Marys, Woodstock, London, and the
area from Thamesville through Chatham to Lake St. Clair. Average
annual flood damages in the watershed were calculated to be over 1.5
million 1975 dollars, of which 57 percent is in Chatham and 20
percent in the vicinity of London. Related in part to flooding is
erosion of streambanks and dikes, primarily in the lower watershed.
Erosion of topsoil is also a significant problem.
The inadequacy of water-based recreational facilities to meet
demands and the potential loss of prime agricultural land were also
identified as problems common to the watershed. Other water
management problems of local importance include negative effects of
artificial land drainage, water supply interference and ground water
quality impairment. Communication and co-ordination problems were
also noted.
In order to develop effective courses of action to resolve these
problems, water management objectives were developed and alternative
courses of action were evaluated. With respect to water quality
objectives, it was concluded that the short term objective should be
to maintain existing water quality where it is satisfactory for fish
and aquatic life and recreation, and to improve quality to this
level where it is presently degraded. The long term objective is to
upgrade water quality as much as possible in order to enhance
conditions for fish and aquatic life, as well as to maximize other
beneficial water uses. Dissolved oxygen criteria and other specific
water quality criteria which would allow this objective to be met
were developed.
It was concluded that flood control in the basin would require
the construction of one or more large dams, and a detailed flood
control benefit-cost analysis of proposed major dams was carried
out. Moreover, as flood control and water quality improvement
options are closely interrelated, various combinations of the
proposed reservoirs and waste management options were examined in a
systems context.
As provincial studies of both the Lake Erie and Southwestern
Ontario regions recognized London to be a major growth centre, and
recommended it continue in that role, one objective was to develop a
water management plan which would allow London to expand to its
projected 2001 population while maintaining satisfactory stream
water quality. This will also allow for the re-direction to London
of population growth from other areas of the watershed where the
capacity of resources to sustain growth will be reached within the
planning horizon.
However, it is recognized that a variety of other considerations
must be taken into account in determining the most desirable
distribution of growth. Population projections based on official
plans and 1961-71 trends, giving a 2001 population of 500,000 at
London, were used in evaluating water management options. However, a
significantly lower growth rate, such as a recent TEIGA estimate of
a 2001 population at London of 338,000 to 350,000, would
fundamentally alter the evaluation of options. Thus, options which
would meet water quality objectives at lower projected populations
were also considered. On this basis, the major waste management
options available to. the City of London were reduced to: tertiary
treatment (to stream quality effluent); diversion of sewage by
pipeline to Lake Erie; or the operation of the Glengowan dam,
primarily for flow augmentation, with the continued use of
conventional sewage treatment.
The proposed reservoirs and the sewage treatment options for
London were then evaluated in system configurations. The primary
evaluation criteria for this analysis were flood control
benefit-cost ratios and the total system net cost in present value
terms. Twenty-two system options were evaluated in detail. The next
analytical stage involved evaluation of non-quantifiable factors
such as recreation and environmental effects of capital works.
Additional objectives utilized at this stage were: to minimize both
the loss of prime agricultural land and environmental disturbance
due to capital construction projects, especially dams; and to
increase water-based recreational facilities in the basin.
When all these factors had been considered, it was concluded that
the preferred option is to construct the Thamesford dam primarily
for flood control, the Glengowan dam primarily for flow
augmentation, and to utilize conventional treatment at London.
However, if it is decided that development of a limestone deposit
precludes construction of the Thamesford dam, the preferred option
is to construct the Wardsville dam for flood control, the Glengowan
dam primarily for flow augmentation, and to utilize conventional
treatment at London. If the growth limitation of 480,000 for London
associated with this option is decided to be unacceptable, then
other options, such as provision of tertiary treatment or
construction of a sewage pipeline to Lake Erie can be considered.
| No. |
Recommendation |
| 1 |
As the Glengowan dam is
common to each of the preferred options, construction of the
Glengowan dam first would offer maximum flexibility in
choosing other capital construction projects. Decisions as
to whether to construct the Wardsville dam or the Thamesford
dam could then be made. The decision as to whether to
utilize conventional treatment or eventually a sewage
pipeline from London to Lake Erie could be deferred to the
early 1990's. Accordingly, it is recommended
that the Glengowan dam should be constructed first, for the
primary purpose of flow augmentation. Furthermore, a study
should be made of what type and level of recreational use,
if any, could be provided at the reservoir. |
| 2 |
It is further recommended that the Upper Thames River
Conservation Authority and the Ministry of Natural Resources
investigate in detail, as soon as possible, the question of
the limestone deposit at the Thamesford dam site to
determine the opportunity cost associated with its
development, so that a decision can be made as to the
feasibility of constructing the Thamesford dam. |
| 3 |
If construction of the Thamesford dam is feasible,
then the Thamesford dam should be built primarily for flood
control purposes. Furthermore, a study should be made of the
desirable level of recreational use of the reservoir,
ensuring that such use would not seriously constrain the
primary use of the reservoir. |
| 4 |
If construction of the Thamesford dam is not
feasible, then the Wardsville dam should be constructed for
flood control purposes only. A flow retarding structure
rather than a conventional dam should be constructed to
minimize the loss of agricultural land and to protect the
yellow pickerel runs and spawning grounds. Detailed studies
should be undertaken to ensure the design will permit the
safe passage offish, and to determine on a benefit-cost
basis whether a 43,000 acre-foot or a larger retarding
structure is the more economical. The environmental effects
and the effects on road communications of the larger versus
the smaller structure should be considered. There should
also be close consultation with Indian bands concerning the
effects on reservation lands. |
| 5 |
Prior to construction of any major dam, detailed
studies should be undertaken to examine environmental
effects, to determine methods of minimizing such effects,
and to determine what type of discharge structure and
operating practices would best protect both reservoir and
downstream water quality. |
| 6 |
As noted above,
implementation of any one of the preferred options allows
deferral for several years of a decision by the City of
London as to whether to continue discharging treated sewage
to the Thames River or to utilize a sewage diversion
pipeline to Lake Erie.
Accordingly, the City of London should immediately
institute plans to upgrade its sewage treatment facilities
to meet the waste loading guidelines outlined in this
report. Specifically, this involves providing an effluent
from all treatment plants equivalent in quality to the
effluent from the Greenway sewage treatment plant as defined
in this report. |
| 7 |
Although the major options
have great significance to basin wide water management, they
by no means deal with all the basin's water resource
problems. Local water management problems can have a
cumulative effect, so that a localized type of problem,
recurring at several different locations, can have basin
wide implications. A wide range of management options to
deal with urban, rural, reservoir-related and flooding
problems has been considered and applied on a stream reach
and municipality basis.
Urban oriented options include
varying levels of treatment of sewage and industrial wastes,
and growth restrictions. In areas where the remaining waste
assimilative capacity of streams is limited, municipalities
proposing additional growth can consider the installation of
advanced tertiary waste treatment plants producing a highly
polished effluent equivalent to stream water quality, or
waste storage for summer spray irrigation or discharge
during periods of adequate flow. However, for smaller
municipalities, the costs of the required tertiary treatment
may be prohibitive. Moreover, the costs of property
acquisition for waste storage can make this uneconomical and
this approach often involves the use of prime agricultural
land. The alternative to the above treatment options is
growth restrictions.
At several municipalities in the basin, the waste
assimilative capacity of the receiving stream has been
reached or exceeded. Accordingly, it is recommended that the
municipalities of Mitchell, Stratford, Tavistock, Glencoe,
Tilbury and Ridgetown should not increase their waste
loadings from all sources to the receiving stream, and in
some cases should reduce these loadings, as described in
chapter 8 of this report. |
| 8 |
Receiving streams at other
municipalities in the basin have varying capacities to
assimilate additional waste loadings. The additional
assimilative capacity at the municipalities of Woodstock,
Beachville, Ingersoll and Lambeth is limited and long term
growth would be inadvisable from a water quality viewpoint.
At the municipalities of Dorchester, St. Marys, Bothwell,
Thamesville, and Chatham the additional waste assimilative
capacity is not as limited.
Accordingly, these municipalities should adopt sewage
treatment techniques selected from approved options as
described in this report, either to provide immediately
required upgrading or to accommodate additional growth if
such growth is found to be desirable when other factors are
considered. |
| 9 |
Control of urban runoff is
an important consideration in the basin. Although the
significance of pollution loads from this source at each
municipality was not documented during this study, urban
runoff is recognized as a source of stream impairment.
Thus, all municipalities should immediately undertake
studies to determine the significance of existing urban
runoff and runoff associated with future development as a
source of pollutants, and take steps to control this waste
input where it is found to constitute a water quality
problem. |
| 10 |
Most industries in the
basin lie within municipal boundaries and discharge wastes
and non-polluted process waters to municipal sanitary and
storm sewage systems respectively. Most municipalities have
enacted sewer use bylaws to control the volumes and strength
of these wastes in order to prevent polluting materials from
gaining direct access to watercourses.
It is recommended that all affected municipalities
enact and enforce sewer use bylaws to prevent industrial
pollution problems. Industries discharging treated wastes
and process waters directly to watercourses in the basin
should implement waste treatment necessary to meet water
quality objectives as outlined in this report. |
| 11 |
Rural oriented management
practices for water quality improvement include limiting
fertilizer application rates, channel protection programs,
restricting free access of cattle to streams, control of
farm waste discharges, particularly from intensive feedlot
operations, and control of illegal septic tank connections
to drains. Surface runoff to streams from fertilized land is
a significant diffuse source of nutrients which contribute
to excessive aquatic weed growth. Although accurate
statistical information is not available, fertilization of
cropland beyond recommended rates was found to be a general
practice in the basin.
It is therefore recommended that fertilizer
application rates be limited to those recommended by the
Ontario Ministry of Agriculture and Food, using services
such as those at the University of Guelph for determining
appropriate rates. Individual and group activity by the
agricultural community and the active support of government
agencies is important to implement this practice. |
| 12 |
A program of restricting free access of livestock to
streams should be commenced. It is recommended that the
Ontario Department of Agriculture and Food take the lead
role in undertaking detailed study of the implications of
such a program to farmers, of the best methods such as
fencing or vegetative barriers, and of the feasibility of
provincial subsidies to encourage such a program. |
| 13 |
It is recommended that increased environmental
surveillance and enforcement be undertaken by appropriate
government agencies to control farm waste discharges,
particularly from intensive feedlot operations, and illegal
septic tank connections to municipal drains. |
| 14 |
It is recommended that channel protection programs as
described in this report be implemented, with initial
emphasis on areas of greatest need which should be
identified in detail by appropriate government agencies. |
| 15 |
Recommendations 11 to 14
are generally relevant to the entire watershed; however,
particular attention is drawn to headwater areas, where the
need to maintain streamflows at the best possible quality
and quantity is especially important. Any lessening of flows
and stream quality in these areas will aggravate downstream
problems.
Rural oriented management practices and conservation
practices should be applied with special rigor in headwater
areas, and municipalities in these areas must pay special
attention to sewage disposal practices to safeguard both
local and downstream water uses. |
| 16 |
It is recommended that resolution of water quality
problems in existing reservoirs be achieved by the two
conservation authorities through appropriate combinations of
bottom draw, destratification, algae control, disinfection
of swimming areas, or modified operating policies as
outlined in this report for each reservoir. |
| 17 |
In evaluating water
management options, the assumption was made that, as
specified in operation manuals, discharges from Wildwood and
Pittock reservoirs would be maintained at minimum rates of
40 cfs and 15 cfs respectively for flow augmentation, and
that Fanshawe Dam would be operated on a flow- through basis
during low flow periods. An analysis of historical flow data
indicated that these rates of flow have generally been
maintained on a monthly basis, but that on a daily basis,
flows have been less than specified for significant periods.
Accordingly, it is recommended that these reservoirs
be operated in such a manner as to ensure the maintenance of
the specified minimum flows on a daily basis. It is also
recommended that there be close liaison between the Ministry
of Natural Resources and the Ministry of the Environment to
ascertain if alterations to these operating schedules would
optimize the use of existing reservoirs for flow
augmentation, without adversely affecting other uses. |
| 18 |
Water based recreation
relates largely to existing and proposed reservoirs.
Improved water quality will enhance recreational use of
streams, but this use is restricted by limited public
access.
Although a significant increase in recreational use of
existing reservoirs is not practical without jeopardizing
their primary use for flood control and flow augmentation,
it is recommended that the Upper Thames River Conservation
Authority and the Ministry of Natural Resources undertake a
detailed computer analysis to determine what modifications
of reservoir operating practices would optimize their flood
control and flow augmentation use and enhance their
recreational use potential. |
| 19 |
Channel erosion problems in
the lower watershed below Chatham are presently the subject
of a $7 million streambank and dike stabilization and
rehabilitation project.
It is recommended that a program of corrective action
concerning bank erosion from Chatham, upstream as far as
Delaware, should be initiated by the Lower Thames Valley
Conservation Authority in line with the recommendations in
the 1971 report by James F. MacLaren Limited entitled "Flood
And Erosion Control Works On The Lower Thames River From
Chatham To Delaware". |
| 20 |
Soil erosion control programs including strip
cropping, crop rotation, diversion terraces, grassed
waterways and vegetative buffer zones or reforestation
should be implemented throughout the watershed, with initial
emphasis on areas that should be identified by staff of the
Ministries of Agriculture and Food, Natural Resources, and
Environment. |
| 21 |
It is recommended that environmental impact
assessments of land drainage proposals be undertaken to
screen out or modify proposals which would damage the
environment and that selected wetlands of ecological
importance, such as the Zorra swamp, be protected from
further drainage. |
| 22 |
Prevention of water supply interference and ground
water quality impairment, rather than remedial action after
the problem has occurred, should be practised using
procedures detailed in chapter 7 of this report. |
| 23 |
To overcome communication and co-ordination problems
relating to water management in the basin, and to implement
planning on a watershed basis, a joint committee of
government agencies and other appropriate bodies should be
established. The committee should include representatives of
the Ministries of Agriculture and Food, Environment,
Housing, Natural Resources, and Treasury, Economics and
Intergovernmental Affairs, the two conservation authorities,
municipalities, citizen groups and the agricultural
community. |
| 24 |
Another aspect of communication and co-ordination,
raised during the Public Consultation Program, related to
the division of the watershed into two conservation
authorities, because of the interrelationships of water
resource problems and solutions in the upper and lower
watershed, and in order to further the basin wide approach
to water management advocated in this report... It is
recommended that consideration be given to the amalgamation
of the Upper Thames River Conservation Authority and the
Lower Thames Valley Conservation Authority into a single
authority. |
| 25 |
Regulation of new
floodplain development is a vital aspect of flood control.
Controls of such development have already been implemented
in some areas of the watershed.
It is recommended that further controls of floodplain
development under the planning act and through regulations
administered by the conservation authorities be developed. |
| 26 |
Flood warning, which can be an effective measure in
reducing flood losses through temporary evacuation of people
and damageable goods, requires an efficient flood warning
system to be successful. It is recommended that the
Conservation Authorities Branch and The Conservation
Authorities consider the development of an improved flood
warning system. |
| 27 |
For long term flood control, flow augmentation and
erosion control benefits, it is recommended that sound
conservation measures such as reforestation, sound
agricultural tillage, use of appropriate ground cover, and
preservation of water retaining areas be encouraged and
implemented. Reforestation and establishment of shrub cover
along streambanks should be directed to areas where they
would specifically aid in erosion control, streambank
stabilization, and the improvement of fish habitats. |
| 28 |
It is recommended that municipalities and government
agencies encourage and enforce careful construction
practices during drainage ditch installations and other
construction activities in and along watercourses. |
| 29 |
It is recommended that development in areas of sand and
gravel not be permitted to hinder infiltration or to degrade
the quality of infiltrating water. This is particularly true
of areas of municipal water supply, such as the Woodstock
well field. In addition, areas providing significant
baseflow such as the Harrington-Lakeside moraine should be
protected. |
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