Runoff > Solutions > References
can change the hydrology (water flow amounts and patterns) of
an area to varying degrees. Where natural vegetation and soil
structure once allowed the gradual absorption and slow through-put
of rain and snowmelt, paved streets and buildings speed delivery
of both water and pollutants to our waterways. Pollutants from
commercial, industrial and residential activities that may appear
insignificant at their source are transported by rain and snowmelt
into storm drains that flush the wastes into rivers, lakes, or
marine waters. These pollutants commonly include nutrients, sediments,
pathogens and toxins. In developed areas, surface runoff is increased
by changes in slope due to landscaping and increasing impermeable
surface area of pavement and buildings. Contaminants accumulated
during dry periods are picked up by the next rainfall and quickly
moved to the drainage system. This is when discharges can be most
dangerous, because "first flush" concentrations of toxins
in streamflow with urban development (MELP [now WLAP] & MMA,
of us can contribute to polluted runoff in many ways, often
without realizing it. Car washing and maintenance can release
detergents, salts, anti-freeze, and oils onto the pavement
and then into storm drains and ditches. Pollutants from vehicle
exhaust and backyard burning eventually settle to the ground
and are washed into adjacent waterbodies by the next rainfall.
Wearing of disc brake pads can be a major source of copper
in urban runoff. Households with lawns or gardens can use
more chemicals on a given area than commercial growers. Half
of all households with yards in British Columbia use fertilizers
and one-quarter use pesticides. Excess amounts of these compounds
find their way into the soil, ground water and adjacent surface
and commercial businesses also contribute to polluted
stormwater runoff through accidental spills and leaks,
and through use and discharge of potentially toxic compounds.
Many industries are required by their liquid waste management
permits to collect, monitor or treat stormwater. However,
uncontrolled runoff from some industries remains a significant
stormwater runoff combines the worst of industrial and
residential runoff in the variety and concentration of
metals, particulates and petroleum compounds deposited
by vehicles. Although stormwater runoff is generally more
contaminated in urban areas, it also poses concerns in
towns and rural areas, where erosion and sedimentation
from roads, road-dust abatement chemicals and road salt
contribute to pollution.
are complex systems and the connection between human activities
and the potential impacts on water quality are not always
clear. The most effective and economic way to deal with NPS
in an urban setting is to prevent the pollutants from reaching
the water in the first place, rather than trying to remove
them after-the-fact. Individually, people need to understand
how their actions have the potential to contribute to NPS
pollution. Once they know this, they can make decisions about
changing the way they do things to minimize their impacts.
developers and elected officials also need to understand how their
decisions can help prevent NPS pollution. In the past, stormwater
has been considered a threat to property which should be removed
quickly before flooding problems occur. In fact, stormwater is
a valuable component of the water cycle and should be thought
of as a resource rather than a liability. Stormwater can play
an important role in recharging ground water supplies and maintaining
stream base flows. However, it must be allowed to absorb into
the ground rather than flow over impervious surface areas picking
up the wastes of urban living on its way to streams, lakes and
can address stormwater and other non-point sources of contamination
by implementing pollution
prevention plans for their operations.
Natural site features such as riparian corridors, streams, lakes,
wetlands, surface depressions, soils and vegetation are integral
to the hydrologic cycle. These features help to store, infiltrate,
evaporate and cleanse stormwater runoff. Removal or modification
of these features in conjunction with the increased impervious
area associated with development causes adverse downstream impacts
that include increased runoff flow rates and volumes, contamination
of receiving waters, destruction of habitat and reduced ground water
recharge. Preservation of key natural drainage and habitat features
through careful planning can minimize the adverse impacts of development
setbacks and easements are approaches which can be used to protect
the natural features discussed above. Buffer zones are strips
of vegetation, either natural or planted, around water bodies.
Such vegetated zones help reduce the impact of runoff by trapping
sediment and sediment-bound pollutants, encouraging infiltration
and slowing and spreading stormwater flows over a wide area. Setbacks
are restrictions on development activities within a specified
distance of a stream bank or other water resource. They can prevent
or minimize erosion and gully formation, thus minimizing sedimentation
and associated nutrient enrichment downstream. Easements are "green
belts" around water ways which can be used to protect the
water and also provide parks and recreational areas for residents.
Easements may be negotiated with landowners and passed on to future
owners as part of the deed to the property or purchased outright.
in impervious area can be undertaken by reducing the overall size
of the developed area, and/or by reducing the amount of impervious
surface created within the developed area. Disconnection of impervious
surfaces can be undertaken by directing runoff from roofs and
paved surfaces over vegetated surfaces before it reaches the drainage
The amount of a particular pollutant that can be removed from
runoff depends on the nature of that pollutant. The removal
of oil and grease from stormwater runoff may be accomplished
by taking advantage of the fact that oil and grease will generally
rise to the water surface under non-turbulent conditions;
heavier sludges may sink under the same conditions. Some of
the constituents typically found in urban runoff, such as
lead and hydrocarbons, are largely associated with the suspended
particulate fraction. Removal of suspended solids can therefore
be expected to effect significant removals of other particulate-associated
pollutants (e.g., lead and hydrocarbons) as well. The separation
of suspended solids and associated pollutants from runoff
waters may be achieved by using mechanical solid-liquid separation
devices. Sediment particles can be removed by encouraging
quiescent conditions, filtration or screening.
of the pollutants in runoff are associated with the smaller
particle size fractions of the suspended solids, which are
generally more difficult to remove by physical treatment
processes than larger particulates. If sufficient time is
allowed under suitable conditions, smaller particulates
may aggregate to form larger particles in a process known
as flocculation. However, many pollutants, such as nutrients,
copper, zinc and cadmium often include a significant soluble
component. Under certain conditions, soluble constituents
may tend to condense and concentrate on the surface of solid
particulates in a process known as adsorption.
body of literature exists on biologically-enhanced methods of
treatment for urban runoff. In addition to the physical removal
of particulates through sedimentation and filtration, systems
with a biological component can remove soluble pollutants such
as oxygen-demanding substances, nutrients, metals and organic
contaminants through uptake and transformation by aquatic plants
and bacteria. Biologically-enhanced treatment systems for stormwater
runoff include wet detention ponds, wetlands, biofilters (vegetated
swales and filter strips), infiltration practices and urban forestry
(MELP now WLAP], 1992). For more information on these systems
and the physical removal processes described above, refer to the
NPS Best Management
There are a number of simple solutions we can incorporate into
our day-to-day activities which will help protect stormwater quality:
- Pave as
little of your property as possible. Use gravel, interlocking
stone or brick instead of concrete or asphalt.
roof drains or gutter systems into rain barrels or over lawns
(but not over onsite sewage systems) where bylaws allow —
not to stormdrains or ditches.
your use of environmentally harmful cleaning products. Use alternatives
such as baking soda, vinegar and hot water as drain cleaner
or vinegar and water as an all-purpose cleaner.
of household hazardous wastes, such as paint, at collection
or recycling depots; never dump them directly into storm drains.
- If you
have oil heating, regularly check your fuel storage tank for
leaks and replace or repair the tank if necessary.
your hot tub and swimming pool water slowly onto your lawn (but
not onto your drainfield), not into storm drains. Where possible,
dechlorinate the water before draining.
driveways and sidewalks instead of hosing them off.
- Make sure
your onsite sewage system is well maintained and meets your
requirements; for more information click
pet wastes and bury them or flush them down the toilet (if you
have an onsite sewage system, bury them away from the disposal
your use of fertilizers and pesticides. If you must use them
follow instructions carefully and be careful using them near
infested vegetation and use natural predators to keep pests
in check. Pesticides can kill beneficial and desirable insects,
such as ladybugs, as well as pests.
yard and kitchen waste and use it to boost your garden's health
as an alternative to chemical fertilizers.
- Grow native
plants in your garden - they require less water, fertilizer
trees, shrubs and plants to slow water running off your property.
This helps to prevent soil erosion and to increase water absorption.
- Set your
mower to cut only the top 1/3 of the grass. Your lawn will be
healthier, absorb more rain and filter sediments.
your car's fuel, oil, brake, transmission, exhaust and cooling
systems regularly. Fix leaks or problems immediately.
- Use a
dropcloth if you choose to fix it yourself.
used motor oil, antifreeze and batteries at collection centres.
- Use phosphate-free
biodegradable products to clean your car. Wash your car over
gravel or grassy area, but not over an onsite sewage system.
Go to a car wash if necessary.
- Use your
car less often. Walk, bike, carpool or take public transit.
Concerted efforts to educate ourselves on how to prevent non-point
source pollution is probably the most important aspect of
addressing the issue. To effectively reduce our impact requires
a fundamental change in attitude and behavior on a day-to-day
basis. Many people fail to make the connection between the
fluid leaking from their automobile, the stormdrain and the
stream it eventually discharges to. They don't understand
that septic systems which go unserviced will eventually fail
and pathogens and nutrients will leach into nearby waterbodies,
which may also be their source of drinking water. In an effort
to have greener, healthier lawns and gardens many home owners
over-apply fertilizers and pesticides — much of which
is washed away with the next rainfall. These are simple examples
but they illustrate the point — our everyday activities
have the potential to impact our water resources.
programs need to be focussed on a target audience and often the
most receptive audiences are school aged children. By exposing
them to the fundamentals of environmental protection at an early
age, we can instill a sense of awareness and responsibility, with
respect to water and other natural resources, that will stay with
them throughout their lives. Under the provincial Eco
Education Program, the Water Crew visits intermediate grade
classrooms (four to seven) and uses a combination of activities
and interactive demonstrations to help the students identify human
impacts on water and generate solutions to help protect water
resources. Many other NPS education efforts are being initiated
throughout the province by government agencies at all levels as
well as community stewardship groups focusing on specific local
Crew presentation to elementary school children
Practices Guide for Stormwater. 1999. Greater Vancouver Sewerage
and Drainage District.
Greenways: Linking Communities to Country, and People to Nature.
1995. The Stewardship Series. Province of British Columbia and
Department of Fisheries and Oceans.
Best Management Practices for Urban and Rural Land
Development in British Columbia. 2004. British Columbia Ministry
of Water, Land and Air Protection, Vancouver Island Region.
Development Guidelines for the Protection of Aquatic Habitat (PDF:
1992. Province of British Columbia and Department of Fisheries
Planning: A Guidebook for British Columbia
Stewardship: A Guide For Planners and Developers. 1993/94.
The Stewardship Series. Province of British Columbia and Department
of Fisheries and Oceans.
Non-Point Source Water Pollution in British Columbia: An Action
Plan. 1999. Ministry of Environment, Lands and Parks (now,
Ministry of Water, Land and Air Protection).
Runoff Quality Control Guidelines for British Columbia (PDF:
6.03 MB / 138 pages). 1992.
Ministry of Environment, Lands and Parks (now, Ministry
of Water, Land
and Air Protection).
Updated: May 2005