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Storm-water runoff threat to water quality

Few people realize that something as seemingly innocuous as a parking lot
can pollute a stream and permanently alter stream habitat for fish, mussels, and other aquatic life.
Storm-water runoff is the precipitation that flows over impervious surfaces, like parking lots and roofs, then down a storm drain and into the nearest stream. This water carries with it oil and antifreeze drippings, brake dust, and other pollutants from those impervious surfaces.
This runoff not only affects water quality; it can also change the very nature of a stream. Precipitation falling on impervious surfaces doesn’t have a chance to soak into the ground and recharge groundwater. Rather, it flows into a stream all at once, dramatically raising the level of the
stream, eroding the streambed and stream banks, and increasing the likelihood and severity of flooding. Also, water flowing over a hot
parking lot can change the temperature of the stream it flows into, impacting aquatic life.
These changes degrade habitat quality for rare aquatic species (like the
endangered Appalachian elktoe mussel and the threa ened spotfin chub) and
game species (such as trout and smallmouth bass). Poor water quality and increased potential for flooding also threaten human health and safety.
Storm water is one of the greatest environmental quality issues facing the
region, yet there are definite ways of controlling it. Through their development ordinances, local governments have a great deal of control over how stormwater is addressed.
For municipalities of a certain size or population density, storm water is regulated under the Clean Water Act, which considers it a point-source water pollutant and requires a permit for its discharge. Storm water in rural areas is generally not regulated but still poses a threat to stream quality.
In addition to governments, there are steps individuals and corporations can take to help the problem,
ranging from capturing roof run-off to constructing pervious parking lots.
As North Carolina faces increased development, storm-water management is a key step in protecting water quality and aquatic habitat, and addressing flood problems.
by Special to the LTN

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