"In a natural landscape, trees and soil help soak up rainwater, but in developed or urban landscapes, rainwater falls onto streets, parking lots, roofs, or other non-absorbent surfaces like concrete and asphalt. Instead of sinking into the ground, rainwater runs off the land, picking up harmful pollutants like nutrients, pesticides, petroleum residues, and sediments along the way. During heavy rains, the water that runs off the landscape is called stormwater." - Excerpt from Coral.org