PugetSoundStartsHere_10-01-15_Tab - page 3

Be a
Drain Ranger!
Storm drains collect stormwater runoff from
our streets, driveways and rooftops and
send it to the nearest stream or lake.
Learn the stormwater path around your
home firsthand by finding the closest storm
drain. Grab your umbrella and watch which
direction the stormwater runoff around your
home or school is flowing the next time it
rains. Where is your nearest storm drain?
Do you know the difference?
Grab a cup of water and test surfaces
outside your home to determine whether
they are pervious or impervious. Water
will absorb into a pervious surface like a
sponge. Water will run off an impervious
surface. Try the driveway, lawn, deck,
garden or sidewalk. What other surfaces
can you test? Why is it important to
understand the difference between
impervious and pervious surfaces?
What is stormwater runoff?
When rain falls in a forest, most of the water is soaked into
the ground, evaporated back into the air or absorbed by
trees. The forest acts like a sponge, capturing and holding the
rainwater before it enters streams and lakes. But when forests
are replaced with hard surfaces, such as buildings, streets and
parking lots, rainwater runs off because it can no longer soak
into the ground. The rain that does not soak into the ground is
stormwater runoff.
The combination of fewer trees and more impervious surfaces
changes the way that rainwater moves across the land, and also
how it enters streams, lakes, and the Puget Sound.
In the forest, about half the water either evaporates or is
absorbed by trees. Another one-third of the rainwater is
absorbed into the soil and slowly makes its way downhill,
through the soil, to waterways. Only about 1 percent of
rainwater flows over the surface of the land to enter a nearby
waterway after a rainstorm.
Urban development changes the amount and the speed
at which rainwater enters streams, lakes and Puget Sound.
Without trees to slow down and absorb the rainwater, or easy
access to soil, about 20 to 30 percent of the rainwater flows
over the surface of the land to enter nearby rivers or lakes.
This surface runoff also reaches these waterways much more
quickly in an urban landscape. Finally, as the rain washes over
streets and lawns, it picks up pollution that is then carried into
waterways. Most of the time, stormwater flows into streams,
lakes and Puget Sound without being treated.
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