What is a Watershed?
A watershed (or drainage basin) is an area of land that collects rainwater and drains it over land and via storm drains into nearby creeks, streams and rivers.
Many people think of watersheds in the context of mountain areas, but here in Langley our watersheds are low-lying.
When rain hits the ground and does not soak in, it will run-off.
Normally the water will run-off first into a creek or stream, then into a river, and then into an ocean. Everything that runs off your property eventually washes into salmon habitats.
The watersheds that we live in are shared, providing homes many creatures, including humans, wildlife, salmon and other aquatic species.
Anything we put onto the land can be carried by run-off and end up in our waterways. Litter, cigarette butts, oil, pesticides, and fertilizer are just a few of the things that routinely go into our waterways. Activities that occur on each individual property are directly linked to the health of our local streams- whether your yard is two metres or two kilometers from the nearest waterway.
What are the problems in our watershed?
As a resident of the Bertrand watershed, you are involved either directly or indirectly in making an impact on the land and water of the area, regardless of how close you are to the Bertrand Creek itself. Whether you depend on a private well or are tapped into the municipal water system, abundant, clean, fresh water is a precious resource that we all depend upon.
Urbanization (or development) has a great effect on local water resources. It changes how water flows in the watershed and what flows in the water. Both surface and groundwater are changed.
As a watershed becomes developed, trees, shrubs and other plants are replaced with impervious surfaces (roads, rooftops, parking lots and other hard surfaces that do not allow stormwater to soak into the ground). Without the plants to store and slow the flow of stormwater, the rate of stormwater runoff is increased. Less stormwater is able to soak into the ground because sidewalks, roads, parking lots and rooftops block this infiltration. This means a greater volume of water reaches the waterway faster and less of that water is able to infiltrate the ground. The reduced amount of infiltrating water can lower ground water levels, which in turn decreases the baseflow levels in our creeks.
In the stream, erosion of stream banks and scouring of channels can potentially occur due to decreased frequency and volume of runoff. This degrades habitat for plant and animal life that depend on clear water. Sediment from eroded stream banks clogs the gills of fish and blocks light needed for plants. The sediment settles to fill in stream channels, lakes and reservoirs. This also increases flooding and the need for dredging to clear streams or lakes for boating.
In addition to the high flows caused by urbanization, the increased runoff also contains increased contaminants. These include litter, cigarette butts and other debris from sidewalks and streets, motor oil poured into storm sewers, heavy metals from brake linings, settled air pollutants from car exhaust and pesticides and fertilizers from lawn care. These contaminants reach local waterways quickly after a storm.
Pollution caused by humans is the biggest threat to our watersheds. There are two types of pollution, point and non-point source pollution.
Point source pollution is “end of the pipe” pollution that can be identified as coming from a specific source such as a factory, industrial plant or some other facility. In the past, most environmental laws dealt with this particular form of pollution, however the most serious threat to our water quality is from non-point source pollution.
Non-point source pollution are pollutants that are carried off the land by stormwater into rivers, lakes, streams or the ocean. The water picks up pollutants left by human actions such as:
- Overfertilization/Pesticide Use
- Failure to pick up after pets
- Dumping auto fluids down storm drains
- Leaving grass clippings and leaves on paved surfaces
- Washing cars on the street or driveway