Environmental Resources Management

Preventing Stormwater Contamination

Newer stormwater drainage systems that discharge to open waters are filtered through traps. These pollutant traps are usually located at the end of the pipe system, and while they do not catch all the silt or litter, they are effective at removing about 90% of the ground pollution from the “first flush” of rain.

These trap systems are not able to remove chemical contaminants from stormwater and older drainage systems (which comprise the bulk of our drainage infrastructure) still discharge chemical and solid pollutants directly from streets and gutters into our waterways.

Most newer stormwater structures, including the systems being implemented now, are what are commonly called "French drains." These drainage systems are pipes covered with small holes that allow the stormwater to drain back into the ground.

As the stormwater infiltrates through the French Drain system, pollution that is carried with the stormwater remains in the system, and is effectively controlled in one place, underground. These systems allow more water to recharge the aquifer instead of being discharged to canals and Biscayne Bay.

While this is far more environmentally beneficial, illegal dumping of oil, litter, and even leaves and grass clippings into storm drains become direct pollution problems for our groundwater and stormwater systems and reduce the capacity to manage stormwater and reduce flooding.