Right as rain

When it comes to lessening the effects of water pollution, residential and commercial rain gardens are becoming increasingly popular in North Carolina, thanks in large part to N.C. State University and its Cooperative Extension Service.

Rain gardens are shallow depressions in the ground that capture runoff from driveways, parking lots and roofs, allowing the water to soak into the ground. That prevents erosion and also keeps potential pollutants out of streams and other water bodies.

In the College of Agriculture and Life Sciences, Biological and Agricultural Engineering specialist Bill Hunt has led the way in research related to rain gardens, also known as bioretention basins or cells, and he teaches and consults with students and professional engineers and developers interested in learning about them.

Also, Horticultural Science faculty members Anne Spafford and Helen Kraus wrote Rain Gardening in the South, an award-winning book that translates Hunt’s research into an easy-to-follow gardeners’ guide for home landscape rain garden installation.

Together, Hunt, Spafford and Kraus are conducting research to quantify rain gardens’ effectiveness in pollution remediation, to broaden the palette of plant recommendations for rain gardens and to design beautiful and effective rain gardens for commercial and residential sites.

Meanwhile, N.C. Cooperative Extension agents across the state have spread the word about rain gardens’ environmental benefits and helped homeowners, businesses, schools and other organizations develop them. With Hunt’s support, four agents also offer the nation’s first rain garden certification programs for landscapers. Hundreds of people across the state have attended the class and passed the end-of-course exam.

Educational publications that Extension has posted on the web (http://go.ncsu.edu/raingarden) explain how rain gardens work: Plants, mulch and soil combine to filter pollutants from runoff and break them down in the soil over time, returning cleaner water through the ground to nearby streams. Rain gardens also reduce flooding and provide habitat for insects and wildlife.

Wendi Hartup, a natural resources agent in Forsyth County, has been one of Cooperative Extension’s leading advocate for rain gardens in North Carolina and the Southeast. She conducts regular rain garden workshops, and she consults with individuals, communities and organizations needing help with designing their gardens, choosing the right site and selecting drought-tolerant plants that can also survive being inundated with water for up to 24 hours. Working in partnership with the county’s Soil and Water Conservation District, she has helped groups find funding for 30 rain gardens.

Recently Hartup compiled statistics about Extension’s statewide 2010-11 rain garden education efforts, which resulted in at least 33 rain garden installations treating nearly 120,000 square feet of impervious surfaces and removing hundreds of pounds of potentially polluting nitrogen and phosphorus from stormwater.

While most rain gardens are small, backyard projects of 100 to 200 square feet, Hartup has led installations of projects of up to 5,000 square feet. Those larger projects at public sites – including a school, a fair ground and a city park – have been accomplished with grants and donations from Cooperative Extension, Lowes Home Improvement, the Soil and Water Conservation District, the Farm Bureau and others.

As long as they are maintained, the installations will yield benefits for generations, not just because they will be filtering pollutants for that long, but also because Hartup had the foresight to install durable signs that will teach visitors about how the gardens work and why they are valuable.

It’s a story she intends to keep telling as community leaders become more interested in using rain gardens and bioretention not only in residential and public spaces but also in large commercial settings.

“To me, rain gardens are great because they are a tiny environmental thing that we can all do,” Hartup says. “And if everyone did it, it would make a huge impact on the environment.”

– Dee Shore