What is a Watershed?

  • A watershed is any area of land from which water drains to a common point, be it a river, pond, stream or lake.
  • Watersheds are separated by each other by topographic features called ridge lines or divides.
  • Watersheds are hierarchical, with smaller watersheds nested within larger ones.
  • Watersheds come in all shapes and sizes and can cross county, state, and national boundaries.
  • A watershed can be as large as all the land draining into the Columbia River, or as small as 20 acres draining to a pond.
  • The term “Basin” is often used to describe the land area draining into a major river such as the Columbia.
  • The term “subbasin” is used to describe a smaller watershed nested with in larger one.
  • A watershed is a place where everything is connected – forest, fields, industry, businesses, houses, and all creatures.


People affect watersheds and watersheds affect the health of our rivers and streams.
Click here to download our Clackamas River Watershed Poster.