HOW IS A RAIN GARDEN UNIQUE?
Rain Gardens are planted to catch rainwater flowing off of paved surfaces such as parking lots.
Rain Gardens are planted with native plants. These plants have adapted to the local climate and can survive without extra fertilizers and insecticides that can pollute local waters.
The soil and roots of the garden act as a filter as they trap automotive fluids and other pollutants.
Cleaner water moves down into groundwater. This groundwater eventually enters a nearby brook or river or pond.
WHAT IS STORM WATER RUNOFF?
Parking lots, streets and sidewalks are called "impervious surfaces" because rainwater won't soak down into them but instead flows over.
Rainwater picks up car oils, litter, loose tar, road salts, etc. as it flows downhill toward the nearest storm drain.
Storm drains are designed to carry excess storm water to the nearest body of water. This could be a river, lake or even the ocean.
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Think of the number of "impervious surfaces" in a city. Consider the amount of automotive traffic as people travel throughout the city. Add in the amount of rain and melting snow on streets and parking lots during the year. You can imagine the amount of water contamination moving from paved surface to storm drain to river.