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Point Source and Nonpoint Source Pollution
Pollution is the
introduction of harmful substances into the environment. These harmful
substances generally come from either easily identifiable locations, known as
point sources, or a number of undistinguishable or hidden locations, known
as nonpoint sources.
An Example of Bioaccumulation Factors
(factors may change based on chemical compound and water concentrations)
Point sources could be:
Specific drainage pipes that
discharge to waterways, including tributaries;
Ship or boat discharge
mechanisms that dump waste or bilge water overboard; or
Smokestacks that emit
pollutants into the air.
Nonpoint sources could be:
Leaking underground septic or
storage tanks or inadequate sewers from which pollutants leach into surrounding
soil, then into the acquifer;
Runoff from lawns and
agricultural fields that are treated with chemical pesticides, herbicides, and
fertilizers that flow into streams and drains;
Runoff from hard surfaces,
such as concrete parking lots and roadways, that carries automotive or
industrial pollutants, such as oil, grease, chemicals, and litter into sewers;
or
Air pollution that becomes
deposited or washed into waterways.
Non-point Source Pollution
Point source pollution sites can usually be seen, then easily tested for
contaminants. If necessary, measures can be taken to prevent further pollution.
Nonpoint sources, however, can cause pollution for many years or decades before
being remediated. Repair or remediation can be difficult and expensive and may
consist of excavation or earth removal, planted buffer zones, and/or runoff
diversion techniques.
The
Issue
Pollutants may cause harm to people, fish, animals, birds, and plants as a
result of:
Direct contact with the
pollutant;
Direct contact with
contaminated water, air,
or soil; and/or
Consumption of contaminated
food.
Containment ponds like this one act as catchments for precipitation that falls
on industrial sites. The ponds ensure that water does not enter the river before
being checked and treated, if necessary.
Pollutants that humans exhaust, dump, spray, drop, and discharge into the air,
land, or water are absorbed into plants and consumed by tiny organisms without
backbones (invertebrates). Small fish, birds, and animals eat these plants and
organisms. Larger fish, birds, and animals eat the smaller fish, birds, and
animals. Humans eat fish, birds, and animals that are large enough to be hunted,
trapped, or caught.
At
each successive level of the food web, persistent toxic pollutants in one
creature are consumed and carried in larger creatures. Predators at the top of
the food chain, including humans, therefore, consume all or most of the
pollutants ingested by smaller creatures. This overall effect is called
bioaccumulation. Bioaccumulation of toxic pollutants is known to cause
cancer, birth defects, and mental and physical deformities.
Point Source Pollution
Condition of Concern
In its St. Clair River Stage 1 Remedial Action Plan,
published in 1991, the Binational Public Advisory Council (BPAC) stated that a
total of 45 municipal and industrial point sources discharge into the St. Clair
River and its tributaries. The report went on to say, Several nonpoint sources
of contamination are also identified.
Evidence of Concern
That statement was based
on pollutants found in the St. Clair River in the late 1980s, which included:
Oil and Grease
Nutrients: nitrogen and
phosphorus
Chloride
Bacteria
Metals: mercury, lead, iron,
zinc, copper, nickel, cobalt, cadmium and chromium
Other toxic contaminants
including: pesticides, PCBs, and chlorinated industrial organics such as
octachloro-styrene, hexachlorobenzene, and hexachlorobutadiene
A cooling tower at Dow Chemicals propylene oxide derivatives plant in Sarnia
allows the plant cooling water to be continually recycled instead of being
discharged into the St. Clair River.
Goals
and Strategies
Relying on federal, state, and provincial standards as well as professional
judgement where standards were either unavailable or inadequate, BPAC found that
these pollutants contributed to several problems within the St. Clair River.
These problems, known as Beneficial Use Impairments (BUIs),
were:
Restrictions on fish
consumption
Bird and animal deformities
Degradation of benthos
Restrictions on dredging
activities
Restrictions on drinking
water consumption or drinking water taste and odour problems
Beach closings
Degradation of aesthetics
Added cost to agriculture
and industry
Loss of fish and wildlife
habitat
The St. Clair River Stage 1 Remedial Action Plan Addendum
(1993) contains goals to eliminate these beneficial use impairments that are
consistent with pollution control strategies. These goals include:
Achieve and maintain an
aesthetically pleasing clean blue water.
Eliminate the need for
restrictions on fish and wildlife consumption.
Ensure there are no negative
impacts on the health of local populations due to water quality.
Ensure that water quality is
safe for body contact at all times.
Ensure that an adequate and
affordable water supply, in quality and quantity, is available from the St.
Clair River for users at all times.
Eliminate spills.
Controlling agricultural use of pesticides and
fertilizers is a crucial to protecting the river.
Remedial Measures
In addition, the 1995 St. Clair River Stage 2 Recommended Plan offers
goals pertaining to point source and nonpoint source pollution.
Point Source Control
industrial, municipal, shipping, air, and water discharges.
Nonpoint Source Control
herbicides, insecticides, soil erosion, fertilizers, nutrients, animal and human
waste, bacteria, storm sewer discharges, lawn runoff, storm runoff, and septic
system failures.
Point
Source Accomplishments
The St. Clair River RAP 2000 Progress Report documents projects that have
been completed or are in process. A few of these are listed here as examples.
Industrial Point Source
Accomplishments:
Dow Chemical Canada
rerouted wastewater, previously discharged into the Cole Drain, to Dows Vidal
Street site for treatment at their private wastewater treatment plant.
Ethyl Corporation
eliminated one wastewater effluent stream.
All companies with major
facilities along the St. Clair River implemented spill prevention strategies.
Municipal Point Source
Accomplishments:
Sarnia completed upgrades
on its Water Pollution Control Plant.
Port Huron implemented a
mercury minimization program at its Wastewater Treatment Plant.
Sarnia has constructed
sewage holding tanks to reduce overflows.
Marysville, St. Clair, and
Marine City separated wastewater sewers from stormwater sewers; Port Huron is in
the separation process.
St. Clair extended sewage
collection and treatment infrastructure to St. Clair Township.
In
addition, industries and municipalities implemented clean water regulations
according to federal, state, and provincial guidelines, initiated toxic
reduction education programs, and completed stormwater impact assessment studies
as part of sewer separation programs.
Industry also implemented measures to control air emissions that can adversely
impact both air and water quality.
This artists impression shows how the St. Clair River has rebounded from a
degraded state to a healthy ecosystem capable of supporting a wide variety of
benthic and aquatic life.
Nonpoint Source
Accomplishments
Watershed and subwatershed
management plans are being written to control urban and rural stormwater and,
thus, prevent contaminants from flowing into waterways.
Standards for controlling
stormwater runoff from new and existing residential developments have been
upgraded.
Education programs are in
place to reduce contaminants from agricultural and rural runoff through
streambank stabilization and vegetation buffer strips.
Education programs are also
in place to reduce contaminants from lawn fertilizers, herbicides, and
pesticides.
Restrictions now limit road
salt application.
Federal, state, and
provincial funding programs are helping to protect and remediate natural areas;
most of these projects are being conducted by grassroots, nonprofit
organizations.
Lambton County has
established hazardous
household waste depositories.
Industrial complexes that
operate private landfills have improved their waste site plans and management.
Education programs and
media stories are encouraging rural property owners to eliminate illicit sewer
discharges and
to repair and maintain
individual septic systems.
Current Conditions
The result of these, and other, accomplishments is that some contaminant
concentrations in the St. Clair River are decreasing. The St. Clair River
Remedial Action Plan 2000 Progress Report states that concentrations of
most contaminants in sediment, air, water, effluent, and sport fish are either
the same as or less than those reported in previous periods. The report goes on
to say, Few, if any, contaminants in any media have been found to be increasing
over the current period. It concludes,
significant actions undertaken to
resolve point and nonpoint source issues defined in the St. Clair River
Stage 2 Recommended Plan have contributed to the overall (improving)
environmental condition of the AOC.
Future Endeavors
Continuing improvements in water quality in the St. Clair River depend, in large
part, on the elimination or significant reduction of foreign
materialspollutantsthat we put into the water, air, and land. The activities
listed above indicate that government and industry are taking major steps to
control and monitor pollutants entering the river, some of which are allowed by
federal, provincial, and state guidelines. More must be done through tighter
restrictions and enforcement, closer monitoring, and continued improvement in
both processes and infrastructure.
Individual
citizens can also help by eliminating or reducing application of toxic lawn
chemicals, making sure that private septic systems are in good working
condition, and disposing of oils, grease, and household hazardous waste
properly. |
