Urbanization increases the variety and amount of pollutants carried into our nation's waters. In urban and suburban areas, much of the land surface is covered by buildings, pavement and compacted landscapes. These surfaces do not allow rain and snow melt to soak into the ground which greatly increases the volume and velocity of stormwater runoff. In addition to these habitat-destroying impacts, pollutants from urban runoff include:

• Sediment
• Oil, grease and toxic chemicals from motor vehicles
• Pesticides and nutrients from lawns and gardens
• Viruses, bacteria and nutrients from pet waste and failing septic systems
• Road salts
• Heavy metals from roof shingles, motor vehicles and other sources
• Thermal pollution from impervious surfaces such as streets and rooftops

These pollutants can harm fish and wildlife populations, kill native vegetation, foul drinking water, and make recreational areas unsafe and unpleasant.