Environmental Engineering Reference
In-Depth Information
When the groundwater recharge decreases, the amount of dry weather
flow decreases, negatively impacting aquatic life and recreational
opportunities.
•
Impaired water quality.
Impervious surfaces accumulate pollutants
that are absorbed by stormwater runoff and carried to lakes and streams.
Examples of these pollutants include:
• Hydrocarbons and trace metals from vehicles.
• Suspended solids from erosive stream banks and construction sites.
• Chlorides from road salt.
• Nutrients from fertilizer and grass clippings and leaves left on streets and
sidewalks, and
• Bacteria from pet waste, goose droppings, and other wildlife.
•
Increased water temperature.
Impervious surfaces are warmed by
the sun. Runoff from these warmed surfaces increase the temperature of
water entering our rivers and lakes. This can adversely impact aquatic life
that requires cold water conditions (e.g., trout).
•
Loss of habitat.
The decline in habitat due primarily to the erosive flows
and the increased water temperature will negatively impact the diversity
and amount of fish and aquatic insects.
•
Decreased recreational opportunities.
Stormwater runoff can neg-
atively impact water resources in many different ways (e.g., decreased water
quality, increased temperature, and decreased habitat). The result is dimin-
ished recreational and economic opportunities for communities throughout
the state.
Stormwater solutions—low impact development
What is LID?
From a stormwater management perspective, low impact development (LID) is
the application of techniques that emulate the natural water cycle described in
the previous section LID uses a basic principle modeled after nature: manage
rainfall by using design techniques that infiltrate, filter, store, evaporate, and
detain runoff close to its source.
Techniques are based on the premise that stormwater is a resource, not
a waste to be quickly transported and disposed. Instead of conveying and
managing/treating stormwater in large, costly, end-of-pipe facilities located
often at the bottom of drainage areas, LID addresses stormwater through small,
cost-effective landscape features often located at the lot level.
Almost all components of the urban environment have the potential to serve
as elements of an integrated stormwater management system. This includes
open space, as well as rooftops, streetscapes, parking lots, sidewalks, and
medians. LID is a versatile approach that can be applied equally well to new
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