Intro | Create a Watershed Display - 1 | Create a Watershed Display - 2 | Water — From the Mountains to the Seas 1 |
Water — From the Mountains to the Seas 2 | Habitat Snapshots | Human Threats From Near and Far | Take Action!
| Resources for Your Displays | Curriculum Links | Watershed Illustration | Canada’s Watersheds Map |
Send Us Your Photos | Blog with Us! | Partners, Sponsors and Credits
Human Threats From Near and Far
Land alterations: Anything we do on land within a watershed affects the water within it. Often when we alter land, the earth can no longer absorb water easily. Instead, it flows directly into surface waters like rivers, and may carry many pollutants with it that can harm both wildlife and humans.
Impervious cover: Impervious cover is the sum total of all hard surfaces within a watershed. It includes such things as parking lots, roads, sidewalks, driveways and other surfaces that limit the ability of rainfall to be filtered through soil to groundwater.
Urbanization: Replacing vegetation with impervious surfaces increases runoff and the amount of contaminates flowing directly into streams and lakes. Channelizing small streams and using storm sewers to transport water quickly can increase flow rates and flood areas downstream, affecting aquatic and human communities.
Land-based water pollution: Did you know that most water pollution is caused by people? Litter, pesticides and herbicides, fertilizers and sewage are among the pollutants that find their way into water.
Vegetation removal: Removing vegetation along river banks and shorelines can destroy habitat for wildlife on the land, and increase sediments and nutrients to the detriment of aquatic life.
Altering water flow: Water flow is modified when water is impounded or diverted by dams. Natural flow regimes, temperatures and amounts of dissolved oxygen are among the elements that change and can harm wildlife.
Agricultural practices: Removing streamside vegetation for pastures, applying fertilizers and pesticides that run off into water, allowing livestock to contaminate water systems and withdrawing water for irrigation in ways that dewater streams can all harm aquatic communities.
Timber harvesting: Timber harvesting can alter stream flow, habitat for forest wildlife and the age of stands. Some animals that need old-growth conditions in forests, like the spotted owl, can be adversely affected whereas others, like the white-tailed deer, might flourish.
Mining operations: Mining activities basically remove soil and rock from the earth, which are then processed in plants. Tailings (residues from ore concentrations) can contain toxic chemicals and are often stored in piles or ponds close to a mine, making them accessible to water and increasing the potential for heavy metal contamination in aquatic communities.
Invasive species: Alien invasive species introduced from different parts of the planet can overwhelm the land and water. The zebra mussel, spiny water flea and purple loosestrife are among the invaders that compete with native wildlife and speed up the loss of their habitats.
Accelerated climate change: The Earth’s climate supports life thanks to the greenhouse effect. Greenhouse gases — carbon dioxide, nitrous oxide and methane — trap solar heat in the atmosphere, maintaining temperatures well above those expected of an Earth without them. With industrialization and rapid growth over the last century, greenhouse gas levels have soared, warming up the planet and resulting in climatic changes. When temperatures rise, air can hold more water and more polar ice melts than refreezes. Warming trends speed up exchanges of water between the land, ocean and atmosphere. These effects can influence the supply of water available in watersheds for plants and waterways, which in turn affects all living things that live in and around them.