Stormwater is basically a way of describing an accumulation of rainwater.  This rainwater is either absorbed into porous surfaces like grass, forests, farm fields, and other areas of “open ground,” or the rainwater collects on non-porous (or impervious) surfaces like streets, parking lots, and rooftops. 

It’s these impervious areas where rainwater collects that is the challenge for stormwater planners.  In order to keep these impervious areas from flooding, streets, parking lots and buildings are often designed with underground pipes and basins that drain this stormwater.  However stormwater managers are faced with three primary challenges:

• drain stormwater quickly in order to prevent flooding, and
• make sure that stormwater is clean of any contaminants picked up along the way, and
• use that stormwater to recharge our groundwater so that drinking water supplies will be available.

In addition, these challenges must be accomplished taking into account existing infrastructure, working within limited space, and using a limited budget as economically as possible.

Stormwater Pollution
Rainfall constantly washes away the dirt and pollution of our urban activities.  This pollution can include litter, oil and other vehicle fluids, and any other chemicals that are on the ground.  As industrial, commercial and residential development increases, dirty stormwater has become a major pollutant to the environment. In addition to their being more contaminants, areas where open soil once soaked up the rain are now covered with concrete and buildings.

Stormwater is often carried through drainage pipes to outfalls into large bodies of water. This water is often not filtered or treated before being discharged and can contaminate our canals, rivers, lakes, the Biscayne Bay, and eventually the Altantic Ocean.

There are three main types of stormwater pollution:

• Litter: cans, paper and plastic bags, and very commonly, cigarette butts
• Chemicals: detergents, automotive fluids, and fertilizers
• Organic waste: leaves, lawn and garden clippings, and animal excrement.

Impacts
There are several factors affecting how much pollution is discharged into our waterways.  The amount of litter and automotive fluid on streets and overuse of pesticides and fertilizers in gardens will affect what enters the drainage system during rainstorms. 

Once the stormwater pollution reaches our waterways, it can be harmful to plants and animals. Large doses of organic pollution can cause fish and other marine life to suffocate from lack of dissolved oxygen (consumed in the process of decomposition), litter can injure unsuspecting fish, turtles, and even manatees and whales, and harsh chemicals (like automotive and cleaning fluids) can be toxic to marine life.