Interesting article, methinks:
part of the article --
Bioswales are slightly concave depressions strategically graded and placed in a landscape so water runoff flows into the depression where it pools. The bioswale is planted with long-rooted native plants that absorb large quantities of water. For example, roots of Indian grass and big bluestem are up to nine feet long, side-oats grama eight feet and compass plant 12 feet. Bioswales slow water velocity, and clean and filter water.
"It's a lot cheaper to handle water at the source. By the time it reaches the river it's almost too late," said Jeff Bergfeld, landscape architect and principal with Bergfeld Landscape Architecture Studio in Henry. "Compare the cost of concrete pipes and collection basins versus a shallow bioswale with native vegetation that promotes shade trees and reduces urban heat buildup."
Morton Arboretum in Lisle west of Chicago recently redesigned its parking lot with permeable paving and bioswales. The project is attracting national and international attention.
Rainwater typically swept across the old impermeable parking lot at Morton Arboretum, carrying oil residue and pollutants into Meadow Lake. Kurt Dreisilker, manager of natural resources at the arboretum, said the design has already started to positively impact the ecology.