A watershed is an area that sends all of its
water to the same place. As you know, water runs
downhill. Surface water collects into larger and
larger streams, then into larger and larger
rivers. Eventually, it winds up in the sea. You
can see an example of watersheds in the Santa
Barbara, Ca area here: watershed
As the water moves, it picks up things like
nutrients, pollution, soil, and living things.
What happens upstream has a large influence on
what happens downstream.
Sometimes watersheds are pretty obvious. If you
live in a valley, you can see where all of the
water on the surface goes. You won’t see all of
the water though, because some water goes
underground. It might have a much longer journey
to the sea.
You can look at watersheds at different scales.
For example, you might study the watershed that
winds up in a small stream. That area will
probably be small. You could also study the
watershed that is drained by the Mississippi
River. That will be HUGE. It will contain many,
many smaller watersheds.
Why might an ecologist study areas by watershed
instead of by artificial boundaries like counties?
If you are interested in watersheds, you might be
interested in studying ecology, geology, or
Thanks for asking,