Rain gardens were first designed in Prince George county, Maryland to combine the two goals of aesthetics and water quality. Also known as bio-retention areas (not ponds!), rain gardens are landscaped areas that treat and retain stormwater runoff. These areas can be managed in a number of ways, either manicured and given high attention, or allowed to blend in naturally with the local growth. It is important, however, to use hearty local plants that are capable of adapting to the conditions of the region.
Rain gardens provide us with a number of important services that will ease the burden on the local stormwater management system. By trapping water in a depression, we slow its movement from the surface of the land, giving it more time to permeate into the ground and be absorbed by plants, in contrast to running off into the sound or ocean. Plants in the garden then filter the water and remove particulates and nutrients, both of which contribute to poor water quality in the surrounding waters.
 Rain gardens are very adaptable and can be appropriately located on just about any piece of property. Their size can be tailored to the amount of runoff and the quality of the soils in the area, as can the plants that populate the garden. Often, one sees rain gardens in parking lot medians and other commercial areas, but they are attractive in a residential setting as well. In all cases, rain gardens are an important feature to reduce the amount of stormwater runoff in a community.
Due to the shallow water table in the coastal region, the design of rain gardens here is especially important. Gardens must be no more than 6-9 inches deep, allowing enough of a dry soil barrier between the surface and the water table for absorption of pathogens and nutrients in the water.
Raingarden Links
NC Cooperative Extension Backyard Raingarden
http://www.bae.ncsu.edu/topic/raingarden/
Vegetated Swales
 Effective Low Impact Development strategies often include more than one stormwater reduction technique. Vegetated swales work well in cojunction with raingardens or they can be effective on their own. They are broad, shallow channels with dense vegetation (often grass) covering the side slopes and bottom. Swales can be natural or manmade, and serve to trap particulate pollutants, increase infiltration, and reduce the flow of stormwater runoff. A swale is much shallower than a ditch, and is designed to hold water following storm events for a limited period of time, from hours to days.
Many swales can be easily maintained by lawn equipment, are relatively inexpensive to construct, and can reduce the amount of municipal water used in irrigation systems. Vegetated swales are best used in conjunction with wet ponds, infiltration strips, constructed wetlands and rain gardens. Swales should be crowned by native trees, as a single tree has been found to reduce runoff by thousands of gallons a year. They are a simple and inexpensive way to irrigate vegetation, as well as reduce potentially harmful stormwater runoff.
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