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Urban
runoff occurs when water moves off of “developed” land into
waterbodies. “Developed”
means that vegetation has been scraped away and replaced with some sort
of impermeable surface. An
impermeable surface is one through which water cannot penetrate (as it
could through natural vegetation, like a forest or meadow floor).
The
water just runs off until it gets to a water body or a permeable surface
like a forest or meadow. Impermeable
surfaces include rooftops, parking lots, roadways, airports, and malls.
All of these surfaces are part of the Urban Development that
occurs in cities, where there are a lot of people and concrete.
What does Urban Development look like in the Satellite
Image of the Barataria & Terrebonne Watersheds? What does Urban Development look like in the Aerial Photographs of
each smaller watershed where it is present within the Barataria &
Terrebonne Watersheds? How
does this land use cause Non-Point Source Pollution? Urban
runoff can contribute several different types of pollutants including
organic matter/low dissolved oxygen, nutrients, sediment, oil and
grease, metals, heat, and disease-causing organisms.
Any time these pollutants end up on concrete or rooftops, rain
can easily carry them into bayous, lakes, and bays, and cause pollution. ·
Organic matter comes from the
clearing the land of plants related to development, lawn clippings, and
pet manure. ·
Nutrients come from lawn
fertilizers and pet manure. ·
Sediment comes from the clearing
the land of plants related to development or canal digging.
·
Oil and grease comes from
machinery and equipment. Sometimes
people change the oil in their cars or trucks and dump it in storm
drains. Storm drains
don’t carry water to treatment plants.
They carry water straight to rivers, bayous, lakes and estuaries.
Storm drains are only for rain water, not
leaves, grass clippings, oil, or grease! ·
Metals come from
machinery, equipment, industrial businesses, and cars and trucks.
·
Heat is a pollutant!
Some cities have a lot of pavement.
Pavement reflects some heat and stores some heat.
When it rains and the water runs off of the pavement, the
pavement can make the water hot. Hot
water holds very little dissolved oxygen. ·
Disease-causing
organisms comes from pets in the cities.
Some people leave their pets’ waste on sidewalks and streets.
When it rains, the pet waste gets washed into storm drains and
out to the local bayou, lake, or bay.
What can you do to prevent this pollution? |