What is a Watershed

Watershed Defined:

a watershed is the land area that drains water to a particular stream, river, estuary or bay. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map.

Not only does water run into the streams and rivers from the surface of the watershed, but water also filters through the soil, and some of this water eventually drains into the same streams and rivers

Watershed Diagram

The diagram below suggests a typical watershed that starts with small head-water streams in the higher elevations of the drainage basin. Water flows downhill from the drainage divide into larger streams, eventually joining a river. As more tributary streams join the river, the volume of water increases. This river eventually flows downstream into an even larger river at the confluence


A Healthy Watershed

Watersheds direct­ly affect water quality, whether it’s for drinking or recreation.  For example, algae blooms or anoxic events resulting from nutrient rich runoff draining into waterway, harm watershed health, as do pesticides and contaminants.  PEI is dependant on its ground water supplies so extreme care must be taken to protect it.

An Unhealthy Watershed

Watersheds affect wildlife. The polluted water supply that results can become harmful to humans. Aquatic life quickly suffers the effects of watershed pollution while new pollutants introduced into ecosystems alter wildlife habitats. This reduces biodiversity by eliminating some species and introducing new, invasive ones that destroy the native species. That, in turn, can affect the food chain in our watershed, from microbial organisms that feed birds and animals to fish that feed humans.

Coming Soon:

  • Our Watershed Community -A Sense of Place
  • The Rivers, Streams and Estuary
  • The Importance of Riparian and Buffer Zones
  • Hydrology of a Watershed
    • Surface Water 101
    • Ground Water 101