Protecting Your Watershed

Discovering a Watershed
What is a watershed? Wherever you go, there you are, in a watershed. A watershed is simply all the land area that drains to a specific point. Browse a map and you can find your watershed by finding the closest stream. Trace up the stream to its furthest point upland and you reach the headwaters; trace down and you reach the mouth at a larger stream, a lake, or the Pacific Ocean. The surrounding ridgetops define the watershed boundaries.

And there you are. The land drains into tributaries and tributaries flow into the river. As the water flows downhill, it moves over the land or drains through the soil. Along the way, water picks up woody debris, leaves, and needles that provide the foundation of food and shelter for aquatic life in streams. Water can also carry motor oil, fertilizer, pesticides, and eroded soil. Small actions like driving the car, fertilizing pasture, or even walking the dog can inadvertently pollute the watershed you live in. As the tributaries flow into the river, so do the pollutants. It all adds up.


Watershed Functions: How We Change Them
A watershed does three things, but our activities can disrupt its usual cycle:

1) Captures water.
Rain naturally enters the earth through soil, roots, and animal tunnels. When buildings, pavement, and other hard surfaces cover the ground, infiltration is hindered. Instead of being absorbed, water runs off into road ditches and into the nearest stream, causing severe stream erosion and floods.

2) Stores water.
After rain enters the soil, it fills the spaces between rocks and soil particles and becomes groundwater. Shallow groundwater enters the plant root zone where roots and soil organisms help to break down pollutants. Deep groundwater enters an area like a refrigerator: dark and cold, where little biological breakdown occurs. Septic system effluents, spilled motor oil, and excess fertilizers and pesticides can reach deep groundwater, polluting public and private wells. In Oregon, about 5 percent of private wells are polluted.

3) Releases water.
Springs, wetlands, and floodplains slowly release groundwater into lakes and streams. When these areas are filled or drained, water storage is reduced, and water runs quickly into the stream. Floods can be more frequent and damaging, while summer flows may be low or nonexistent. Land use changes can disrupt the natural functions of a watershed. As a result, streams can erode and flood more often, water quality may decline, treatment costs may rise, and fish communities may collapse. Read on to identify problems in your watershed and find out what you can do to restore your watershed to better health...