Pollution in Stormwater Runoff
When many people think about pollution, images of smokestacks belching poison gas come to mind. However, pollution may be much less obvious. Pollution can be defined as the emission of harmful substances into the environment, due to human activities. Humans are the only species that pollute; elsewhere in nature, all is recycled.
Pollution is found virtually everywhere on earth—in the air, in fresh water, in the oceans and on land—even in remote polar regions. Pollutants travel through the water cycle and are transported by physical processes such as rain, runoff, evaporation, wind, currents and tides. Greater understanding of these processes has led to the realization that pollution is a global problem. Everything we do has an effect on the environment somewhere else, near or far. At the same time, however, positive actions also have far-reaching effects.
Pollution can have a wide range of health effects on people, animals, plants and ecosystems. Even in Victoria, a city that is known for its natural beauty, past and present human activities have taken their toll. We all contribute to the problem.
Where does pollution come from?
In the past, knowledge about the effects of pollution in the Capital Region was generally low. Consequently, waste materials from various industries were often disposed of in the harbours. Although some substances are broken down by natural processes, others persist, and remain bound in sediments today.
Gradually, practices changed. Waterfront industries must now follow strict regulations about how they manage their wastes. But not all changes over the years have been favourable for the environment. As the population of Greater Victoria grew, the activities of individual people and small businesses had a greater cumulative effect. Today, the main sources of ongoing marine pollution are scattered throughout watersheds, the area of land that drains rainwater to the receiving environment. Such pollution is called non-point source
Non-point source pollution has a number of widely dispersed sources that are difficult to identify, such as automobile pollution, leaking septic systems, and runoff from farms, roads, gardens and lawns. Point-source pollution, on the other hand, can be attributed to some specific location, such as a factory smokestack.
A big part of the problem with non-point source pollution is the increasing amount of impervious surfaces
(i.e. roads, buildings, parking lots) in the city. These prevent rainwater from soaking into the ground; instead, it flows across the surfaces, picks up contaminants, and rushes directly into streams, wetlands and the ocean.
The various harbours in the CRD have different pollution sources, as summarized in the table below.
|Harbour ||Main pollution sources |
|Victoria Harbour || |
- Runoff from roads, parking lots, gardens
- Litter thrown directly into Harbour
- Contaminated sediment (from historic practices)
|Gorge Waterway || |
- Runoff from roads, parking lots, gardens, farms
- Lower Gorge: contaminated sediment (from historic practices)
|Portage Inlet || |
- Runoff from roads, parking lots, gardens, farms, Trans-Canada highway
- Excessive sediment (from erosion in streams)
|Esquimalt Harbour || |
- Runoff from roads, parking lots, gardens, farms
- Contaminated sediment (from historic practices)
|Esquimalt Lagoon || |
- Leaking septic systems
- Runoff from roads, parking lots, gardens, farms
What are the main pollutants of concern?
The following pollutants are among those commonly found in the harbours and watersheds of the CRD.
Hydrocarbons are molecules made up of hydrogen and carbon. They have different properties depending on the size and arrangement of the molecules. Hydrocarbons generally do not easily dissolve in water. Small molecules such as methane are gases, larger molecules such as most components of gasoline are liquids, and very large molecules such as heavy oils are thick, viscous liquids. Hydrocarbons are present in motor oil, gasoline, coal, natural gas, solvents (e.g. paint thinner), plastics and pharmaceuticals.
Gas is a complex mixture of up to 500 different types of hydrocarbons that contain between 4 and 12 carbon atoms. Gasoline may enter the environment through: the air, when it is burned in engines; the land, when it leaks or spills from containers or vehicles; and the water when it is washed off the land or spilled/leaked from boats. Some of the components of gasoline include:
- branched, straight-chain and cyclic alkanes, the dominant hydrocarbon type
- benzene, toluene, ethyl benzene and xylene (known collectively as BTEX)
- polycyclic aromatic hydrocarbons (PAHs) (which are also common in creosote, a wood preservative)
- sulphur and nitrogen compounds that naturally occur in crude oil
- various additives designed to improve engine performance, reduce emissions, or inhibit corrosion, among other functions. These include methylcyclopentadienyl manganese tricarbonyl (MMT) and methyl tertiary-butyl ether (MTBE).
When gasoline is burned, chemical reactions in the air cause the formation of ozone, aldehydes and peroxyacetyl nitrate (PAN), which contribute to photochemical smog. Particulate matter is also produced, as evidenced by black or brown smoke e manating from trucks, buses, and cars.
These are metallic elements that have a high atomic weight. They include arsenic, lead, mercury, copper, zinc, manganese, and cadmium, among others. Heavy metals are naturally present in the earth's crust, and cannot be created or destroyed. Various heavy metals and metallic compounds may be used in paints, plastics, batteries, pesticides, wood preservatives, pharmaceuticals, dyes, ceramics, electrical appliances, explosives, and dentistry. Some heavy metals, such as copper, zinc, and chromium, are required in small doses by plants and animals, but are toxic in high concentrations. Metals may be released to the environment through mining, coal combustion and the disposal of metal-containing products.
Persistent Organic Pollutants (POPs)
POPs are large hydrocarbon molecules that usually contain one or more chlorine atoms. They are more difficult to break down than regular hydrocarbons. Examples include:
- Dioxins and furans, produced as byproducts in pesticide manufacturing, burning treated wood and chlorine bleaching in pulp mills
- Polychlorinated biphenyls (PCBs), used as insulating and stabilizing liquids in electrical transformers and capacitors, paints and plastics
- Pesticides such as para-dichlorodiphenyl-trichloroethane (DDT), chlordane and toxaphene
- Pentachlorophenol, a wood preservative
The emissions of some of these substances have been substantially reduced in Canada. Wood pulp bleaching using chlorine dioxide (instead of pure chlorine) has substantially reduced dioxin and furan emissions. PCBs are no longer manufactured in Canada, and their use is restricted; however, previously existing supplies are still used. The use and manufacture of DDT has been banned in Canada and in many other countries. Nevertheless, because POPs break down very slowly, historic pollution persists today.
Organotins are organic compounds that contain tin atoms. They are frequently used as pesticides for treating the hulls of ships, to prevent marine organisms from attaching and causing drag. One common example is tributyl tin (TBT).
Wood debris often accumulates on the bottoms of harbours where log booms are stored, and adjacent to saw mills. The debris may contain wood treatment chemicals such as pentachlorophenol.
Nitrates and phosphates
These are nutrients that are necessary for plant growth, but in excess they can cause algae blooms (see "environmental effects," below). Sources of nitrates and phosphates include sewage, fertilizers, and feces of pets, livestock, and wildlife. Phosphates are also common in detergents.
These organisms (e.g. bacteria, viruses and protozoa) may be present where water bodies are polluted with sewage or animal feces. Fecal coliform bacteria are used as indicators of sewage pollution.
Pollutants of Concern in CRD Harbours
The main pollutants of concern in the CRD harbours are summarized in the following table.
|Harbour ||Main pollutants of concern ||Possible sources |
|Victoria Harbour ||Heavy metals (esp. copper, mercury, zinc) ||Historic harbour-side industries; runoff from land-based industries; pesticides |
|Hydrocarbons (e.g. solvents, degreasers, lubricants, fuels) ||Recreational and commercial boats/ships; automobiles |
|PAHs ||Automobile pollution; historic coal storage and combustion |
|PCBs ||Historic industrial pollution |
|Organotins ||Ship hulls |
|Chlorophenols ||Treated wood debris (saw milling) |
|Gorge Waterway ||Lower Gorge): heavy metals - copper, mercury, zinc. |
(Data lacking for other pollutants)
|Historic harbour-side industries; Runoff from land-based industries; Pesticides |
|Portage Inlet ||PAHs, hydrocarbons, heavy metals (suspected) ||Automobile pollution, runoff from industrial sites |
|Nitrates, phosphates, bacteria ||Fertilizers, pet feces, sewage (from cross-connections with stormwater) |
|Esquimalt Harbour ||Heavy metals (arsenic, cadmium, copper, lead, mercury and zinc) ||Ship-building and repair (historical); munitions storage; batteries; Runoff from land sources (historical and current) |
|Organotins ||Ship hulls and ship repair sites |
|PAHs ||Coal and oil storage, transfer and combustion (historical); Fuel spills and leakage (historical and current) |
|Hydrocarbons (e.g. solvents, degreasers, lubricants, fuels) ||Recreational, commercial and military boats/ships |
|Hydrocarbons (e.g. solvents, degreasers, lubricants, fuels) ||Historical PCB manufacturing and storage |
|Wood debris ||Log booming and sawmilling |
|Esquimalt Lagoon ||Nitrates, phosphates, bacteria ||Septic tanks (sewage) |
What effects does pollution have on ecosystems & people?
An important point in discussing the ecosystem effects of pollution is that in many cases we know relatively little about how certain organisms are affected by pollutants. Furthermore, even low concentrations of toxic substances can have harmful effects on wildlife that are difficult to observe. For example, undetectable nervous system damage may affect a bird's ability to find a nest site, care for its young or escape from predators. A chemical that interferes with a fish's sensory perception may cause it to starve because it cannot find its food. Even in humans, cause and effect between pollutants and health can be difficult to establish. Some of the known effects of pollutants introduced above are included here.
- Persistent Organic Pollutants (POPs) are very slow to break down in the environment, and in many cases have an affinity for the fat tissues in animals. Therefore they are difficult to eliminate, and many are subject to biomagnification. This means that they become more highly concentrated as they move up the food chain. Some (e.g. PCBs, dioxins/furans) are endocrine disrupters, meaning they interfere with hormone regulation; this can affect reproduction.
- POPs are subject to long range atmospheric transport by a phenomenon known as the "grasshopper effect." This arises because the compounds are somewhat volatile, and in warm regions they evaporate. Winds transport the molecules in the atmosphere until they reach a colder climate, where they condense and fall to the ground with the rain or snow. Once on land, the cycle may then begin again. In this way, many POPs have found their way to the Polar Regions. People and animals (e.g. polar bears, seals, beluga whales) that live in the Arctic have been found to have high concentrations of POPs in their systems, despite the fact that they have not been directly exposed to pollution.
- Some heavy metals are also subject to the "grasshopper effect" (e.g. lead, mercury, cadmium) and biomagnification (e.g. mercury). Most heavy metals are highly toxic in elevated doses, cause nervous system impairment and damage, organ damage, reproductive effects, and in severe cases, death. Cadmium, arsenic and chromium are carcinogenic (they cause cancer). In addition, mercury can damage developing embryos; copper is highly toxic to fish; and lead causes anemia and neurological damage in mammals.
- Low molecular weight PAHs are highly toxic, and high molecular PAHs are known carcinogens or precursors to carcinogenic compounds. Some PAHs are also mutagens, meaning they cause cellular mutations.
- Automobile pollution is the single greatest source of greenhouse gases such as carbon dioxide and nitrogen compounds, which are causing climate change. Climate change has serious implications for human health and safety, economic prosperity, and biodiversity of species and ecosystems. (See "Related Information" below.)
- BTEX compounds, present in gasoline, are known carcinogens, and some have effects on the nervous system.
- Sulphur and nitrogen compounds, when released to the atmosphere by gasoline combustion, can cause acid rain, which can be directly toxic to vegetation, or change the pH of freshwater bodies so that fewer organisms can live there.
- Ozone and peroxyacyl nitrates (PAN), produced from chemical reactions of automobile (and industrial) pollution, lead to the formation of photochemical smog, the "haze" commonly seen over cities. Photochemical smog is a respiratory and eye irritant, impedes photosynthesis in plants, and is an aesthetic concern as it diminishes the "view" of the surrounding landscape.
- Particulate matter, produced from combustion (e.g. by automobiles, metal smelters, forest fires), can enter the lungs and aggravate or cause respiratory illnesses.
- The gasoline additive MTBE has been shown to cause cancer in test animals, and has a highly disagreeable odour and taste in drinking water, even in small amounts. Consequently, its use has substantially declined. MMT is present in 90% of gasoline and has been shown to increase the emission of hydrocarbons, nitrogen compounds and carbon monoxide.
- Excessive nutrients (nitrates and phosphates), from sewage or fertilizer pollution, can cause explosive algae growth in marine and fresh water. When this occurs, bacteria that subsequently breaks down the plant matter use up oxygen in the water. Other plants and animals that require oxygen may consequently die. This process is known as eutrophication. Excessive algae growth in drinking water reservoirs can interfere with water treatment and cause taste and odour problems. Nitrates in drinking water can also lead to methemoglobinemia or "blue-baby syndrome."
- Organotins are highly toxic to fish and invertebrates. Organotins have been known to cause abnormal shell development in oysters and sex change in certain types of snails. At high levels, organotins are also toxic to the nervous system in humans.
- Accumulation of wood debris on the ocean floor can alter the physical and chemical composition of sediment and smother bottom-dwelling plants and animals. As bacteria break down the wood, they deplete the surrounding water of oxygen.
- Disease-causing organisms that can be present in sewage and animal feces include bacteria such as Salmonella, V. cholerae, Shigella, and E. coli 0157H7; viruses such as Hepatitis and Norwalk; and protozoa such as Giardia. Diseases transmitted by these organisms may cause mild nausea or life-threatening illnesses. Fortunately, improved sanitation and water treatment processes have made outbreaks rare in this part of the world.
How to reduce pollution
Reduce automobile use and emissions
- Automobiles are one of the largest collective sources of ongoing pollution in the local harbours and watersheds. Driving less can have enormous benefits for the environment, while walking and bicycling can also improve your health. Other options include carpooling, sharing a vehicle and taking the bus.
- Switching to a more fuel-efficient vehicle can decrease the emissions of your automobile by up to 50%. Not only do large vehicles such as SUVs pollute more, in many cases they are not as safe as regular cars (see More Information). While you help the environment, you can also save hundreds of dollars a year on gasoline bills.
- Keeping your vehicle properly tuned can cut down on air pollution, and prevent oil, gas and other fluids from leaking onto roads, parking lots and driveways, from where they are washed into water bodies.
Reduce the area of impervious surfaces around your home and property
Roads, parking lots and roofs prevent rainwater from soaking into the ground; instead, it flows into nearby streams and marine areas in unnaturally high volumes, and picks up pollutants along the way.
Reduce the use of chemicals on your lawn and garden
- Have your soil tested to see if it requires any supplemental nutrients (many areas don't).
- Use compost instead of synthetic fertilizers (which has the added benefit of helping to build your soil)
- Encourage beneficial insects, birds and bats for natural pest control
- See natural gardening for more tips and information
- Avoid using pesticides on your property
Reduce the use of toxic chemicals in and around your home
Inspect and maintain your septic system
Business owners need to familiarize themselves with applicable regulations and at minimum should consider adopting "Best Management Practices" (BMPs), to reduce pollution from your enterprise.
Reducing boat pollution
- Make sure trash doesn't get blown overboard; dispose of all litter in receptacles on shore. This includes cigarette butts, which are highly toxic to marine life. Encourage marinas and other ports to provide adequate garbage and recycling facilities.
- To reduce engine pollution, keep your engine well-tuned, eliminate unnecessary idling, and install a drip pan under the engine.
- Choose four-stroke outboard engines over the two-stroke variety, as they pollute less.
- Throttle down near the shore and in enclosed bays - large wakes can cause shoreline erosion.
- Refuel carefully and keep a supply of oil-absorbent rags on board.
- Bilges tend to collect various pollutants such as engine oil, fuel, antifreeze and transmission fluid. Do not discharge the bilge water if it has a sheen to it.
- Bilge "cleaners" usually only emulsify oils by breaking them up into smaller droplets, which simply spreads them out over a wider area on the water's surface.
- Use "bilge pillows" instead, to absorb petroleum products before flushing out the water; dispose of them in approved containers on shore.
- Oil/water separators can be installed in bilge pump discharge lines.
- The best option for disposal of bilge water is pump-out services offered by some marinas.
Cleaning and maintenance
- Rinse your boat more frequently with plain water; this will reduce the need to use cleaners and harsh anti-fouling treatments.
- Use non-toxic cleaners and phosphate-free detergents.
- Do your maintenance work on land. Use environmentally friendly tools, such as vacuum sanders and grinders, to collect and trap dust. Some marinas have this equipment for rent; check with the manager.
- If you sand, scrape or remove anti-fouling hull coating, collect the residue and dispose of it at an appropriate waste facility (contact your local marina).
- Use hard anti-foulants, as they don't leach as much toxic chemical into the water; or, use "non-stick" anti-foulants such as silicon and teflon, which rely on a slick surface rather than toxic pesticides to repel growth.
- Solvents and thinners can sometimes be used more than once by allowing the solids to settle out and draining the clean product off the top. Share leftover paint and varnish.
- Don't "top off" the tank. Know your fuel tank capacity before you start filling.
- Fill tanks to no more than 90 percent capacity - gas that is drawn from cool storage tanks will expand as it warms up onboard your boat.
- Place an absorbent pad or container under the fuel vent to collect accidental overflow.
- Fill portable tanks on shore.
- Do not discharge your holding tank or flush wastes while docked, or when moored near ecological reserves, swimming beaches or shellfish harvesting areas.
- Use pump-out services when they are available. Where they are not, wait until you are in open waters, preferably in areas with strong currents, before discharging the holding tank. Encourage your marina or yacht club to install a pump-out service.
If a spill happens…
- Stop the source of the spill, and then contain the spill with absorbent materials if possible.
- Call Emergency Info BC
Tel: 1.800.663.3456 to report a spill of dangerous (or potentially dangerous) material on land or on water.
- Call the Canadian Coast Guard
Tel: 1.800.889.8852, and on VHF 16, for marine spills.