Evergreen works with volunteers and community members to monitor and restore Metro Vancouver and Greater Toronto Area waterways. Together, we remove invasive plants, reintroduce native plants, monitor water quality and learn about the importance of our local streams.
Read on to learn more about urban watersheds, or visit a subsection for more information and resources:
A watershed is an area of land where all of the water that is under it or on the surface of it goes to the same place.
Urban watersheds face unique stressors that make them some of the most highly-impacted watersheds. As our cities have developed, we have paved most watershed surfaces, causing water to move very quickly over roads, houses, parking lots and other impermeable surfaces, and into stream channels rather than soaking into the soil where it can be stored and sustain stream flow through the year. As a result, many urban streams and the lands around them are degraded and cannot support diverse ecosystems.
Water moving through urban watersheds is often called stormwater: urban runoff that travels through the storm sewer system, making its way to downstream water bodies. For example, in Vancouver, all of the water you see travelling over streets eventually makes its way via False Creek, Burrard Inlet or the Fraser River to the Georgia Strait. In Toronto, all of the stormwater eventually flows into Lake Ontario. Urban runoff often carries a slurry of contaminants that it has picked up from roads, buildings, private and public properties. The everyday actions and behaviours of city dwellers impact stormwater and downstream waterways.
No matter where we are – in the city, on a farm, in a car, on a mountain, or in a ravine – we are in a watershed. This makes us all part of the watershed community and stewards of our waterways.
Biodiversity is the variety of life found in a given area. This can include plants, animals, insects, fungi and other organisms in an ecosystem. Compared to undeveloped areas, we typically see less biodiversity in urban areas due to habitat loss, pollution and ongoing disturbances.
Land surface disturbances leave gaps for invasive plants to take over native habitat. An invasive plant is a non-native species whose interaction causes economic harm, harm to human health and/or environmental harm (Invasive Species Council of Metro Vancouver, 2014). These plants have no local parasites or predators, displace native plants, form monocultures and dominate the ecosystem. They limit the species variety that defines a biodiverse, healthy watershed ecosystem.
The Invasive Species Council of Metro Vancouver and Ontario’s Invasive Species Awareness Program list the key species that threaten the health of our urban ecosystems in Metro Vancouver and the Greater Toronto Area.
Evergreen works with local partners and volunteers to remove or control invasive species, and restore biodiversity by replacing invasive plants with native plants. Native plants are those that occur naturally in a region and were there before European contact. Many invasive plants make their way into native habitats through improper disposal. When you are gardening, it is important to make use of municipally-provided green waste services and avoid placing any yard waste in public green spaces. You can also explore Evergreen’s Native Plant Database to find substitutes for invasive plants you might have in your garden.
Imagine Canada 300 years ago: a biodiverse landscape dominated by towering trees, rocky outcrops, streams alive with spawning salmon, skies full of predatory birds, and forests full of bears and wolves.
Today, many of these streams run underground in pipes, never exposed to sunlight or oxygen, and devoid of habitat for native aquatic and terrestrial species. Our urban streams are connected to the stormwater system; the water that falls on rooftops, driveways, streets and highways flows through sewer grates and pipes and directly into streams that are home to spawning salmon and other essential species. By examining the water quality in these streams, we can begin to understand how urban development impacts these streams and how we can mitigate the harm.
Once a month through Uncover Your Creeks, we sample seven water quality parameters at six sites in Metro Vancouver, one site on Vancouver Island and eight sites in the GTA. The results are tracked and available to any volunteers or interested community members at any time. You can see the data on our Watershed Resources page.
“If climate change is the shark, then water is its teeth.”
Climate adaptation refers to actions taken to respond to the impacts of climate change by taking advantage of opportunities or reducing the associated risks. Climate adaptation is often paired with climate change mitigation, which is the reduction of greenhouse gases. From an urban watersheds perspective, Canada’s municipalities are anticipating more intense and frequent rainfall. This can mean damage to infrastructure and public property, and health impacts due to wastewater contamination in water bodies.
There are many ways that communities can adapt to anticipated climate change in their watersheds. For example, Renfrew Ravine Park lies in the Still Creek watershed, a highly urbanized watershed in east Vancouver and west Burnaby. Recently, a Master Plan was completed by the Vancouver Parks Board that identifies reaches of the stream, which could be restored to better allow the landscape to absorb and respond to extreme events and habitat requirements.. You can see more details in our Watershed Resources page.
As individuals, we can contribute by increasing the permeability and water retention capacity of our properties; de-pave driveways and walkways, build rain gardens and invest in a rain barrel. Retaining water on individuals lots, rather than letting it run off into streams and the stormwater system, reduces erosion and pollution and can minimize the need to water in the dry season.
Interested in reading more about climate adaptation plans in place in Metro Vancouver or the Greater Toronto Area? See our Watershed Resources page.
With generous support from Intact Foundation, Evergreen is connecting residents with opportunities for climate adaption in their watersheds through the Community Climate Adaptation Initiative.