Urbanization and increasing commercial and residential development have a great impact on local water resources. More impervious surfaces (roads, rooftops, parking lots and other hard surfaces that do not allow stormwater to soak into the ground) increase the rate of stormwater runoff. This means a greater volume of water carrying pollution into surface waters and less water soaking into the ground.
These contaminants include:
- Cigarette butts and other debris from sidewalks
- Motor oil poured into storm sewers
- Pesticides and fertilizers from lawn care
- Pet wastes
- Settled air pollutants
- Yard wastes
Less water soaking into the ground also lowers ground water levels, which can dry up streams and hurt stream ecosystems, and can reduce the supply of well water.
Stormwater also erodes stream banks. This in turn degrades habitat for plant and animal life that depend on clear water. Sediment in water clogs the gills of fish and blocks light needed for subsurface plants.
The sediment can also fill in stream channels, lakes and reservoirs, covering the bottom and negatively affecting flow, plants and aquatic life.