Watershed Introduction
What is a Watershed?
• An area of land,
from ridge top to
ridge top, that
collects, stores,
and releases water
to a common
point, such as a
river or a lake
Portland Area Watersheds
Clackamas
Columbia
Sandy
Tualatin
Willamette
Lower
Middle
What’s in a Watershed?
Streams
Rivers
Lakes
Wetlands
Hills
Mountains
Farms
Cities
Houses
Humans
Animals
Plants
Human Impacts on Watershed
Land Use
Pollution
Too much of a good thing
Point Sources
Non-Point Sources
Erosion
Natural
Human-accelerated
Urban Runoff
Runoff from:
Streets
Parking lots
Roofs
Driveways
Lawns
Erosion
Watershed Functions
COLLECT
STORE
RELEASE
Watershed – COLLECT
Geology
Mountains, valleys, etc
Vegetation
Interception
Manmade surfaces
Watershed – STORE
Wetlands, Lakes, Reservoirs
Soil
Groundwater
Snow and Ice
Biology
Watershed – RELEASE
Streams and Rivers
Groundwater
Evaporation
Human Engineering
4 Dimensions to streams/rivers
Longitudinal
Lateral
Vertical
Temporal/seasonal
Watershed Sciences
“Geo” sciences
Hydrology
Chemistry
Biology
Ecology
Geomorphology
Physical shape
Parent material
Soils
Hydrology
Chemistry
Most “water quality”
parameters are
chemical
measurements
Nutrients
Temperature, pH,
DO, etc
Biology
Bacteria
Algae
Plants
Animals
Ecology
Terrestrial
Riparian and Upland Vegetation
Animals
Aquatic
Habitat (pools, LWD, etc)
Vegetation
Animals
How do we study a Watershed?
If our sampling
site is at the red
dot on the
stream, the water
we are testing
could have
interacted with
any of the
watershed area
upstream of that
point.
Clackamas Watershed
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Clark
County
Watersheds
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Sandy Watershed
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Tualatin Watershed
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Lower Willamette Watershed
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Middle Willamette Watershed
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