Where ever you live, managing stormwater runoff is important. Rooftops, roads, driveways, and sidewalks create hard surfaces, which rain and melted snow cannot penetrate. Runoff from those hard surfaces carries pollution, nutrients and sediments into our lakes, streams and wetlands.

Rain gardens can help reduce runoff from your property. A rain garden is a shallow depression that's filled with water tolerant plants. It collects runoff and filters out pollutants before water enters the groundwater.

Size, soil type and vegetation are important factors when designing a rain garden. Rain gardens can be designed in any shape. Long and narrow ones may best fit between houses and sidewalks. Typical gardens are 100 to 300 square feet. For roof top runoff, place rain gardens at each down spout, at low points in the lawn. Each garden should be one-third the size of the roof area being drained. To control driveway and sidewalk runoff, apply these same concepts.

Of utmost importance is the soil. For rain gardens to infiltrate runoff, soil needs to be porous enough to quickly soak up water - ideally emptying within 48 hours. This helps prevent plants from drowning. It also prevents gardens from becoming mosquito breeding grounds.

To test the soil's ability to infiltrate water

• dig a hole 10" deep;
• fill it with water;
• if the water doesn't disappear within 48 hours, you'll need to increase infiltration.

Rain gardens should be placed at least 10' from buildings to prevent foundations and basements from being damaged by water. They should be 35' or more from septic system drain fields, and 50' or more from drinking water wells. Always call the Digger's Hotline (800) 242-8511 before digging.

• Lay out a rope in the shape desired.
• Dig a depression 4 to 8" deep.
• Level the bottom.
• On a slope, create a berm on the downhill side.

Many native plant species are well-suited for rain gardens. If your rain garden is near a shoreline, native plants may be required. Check with your Soil and Water Conservation District or County Environmental Department. For recommendations on plant species and more guidance on rain garden design and construction visit Rain Gardens .

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