It's an ornamental garden that is designed to hold a few inches of water when it rains. You can build one in your yard to receive roof downspout and hard surface runoff. A MUNICIPAL rain garden is built in the street boulevard and holds some of the rainfall runoff from the street pavement. When full (usually just a few inches) any additional runoff just continues on down the street. Gardens are designed to allow the water to soak in quickly, within a day at most. With enough rain gardens, we can improve the water quality of our local streams, lakes and rivers..
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