Water Quality Benefits

Abstract

Green Roofs can be very effective as method for improving water quality. A recent study in Charlotte, North Carolina, showed that in addition to heavy metal pollutants, 10-30 percent of nitrogen and phosphorus pollutants contributed to streams and lakes are derived from runoff from urban roofs. These pollutants are the principal culprits in degrading aquatic habitat. Dust containing a range of pollutants accumulates on roofs until it is washed off with next rainfall. Furthermore, the acidity of runoff from roofs is typically higher than already acidic rainfall.