That lovely, chocolaty brown color comes from loose soil washing off yards, neighborhoods, construction sites, and other bare spots. Storm water washes over bare spots and carries soil particles down into storm drains that dump right into your local creeks!
Unlike sand, which settles out pretty quickly, Northern Virginia soils are full of tiny clay particles, which stay suspended for hours, even days, in our rivers and The Chesapeake Bay. Sediment is one of the primary pollutants in the Chesapeake Bay because it keeps sunlight from reaching the submerged aquatic plants. Those plants are essential habitats for fish, crabs, and numerous invertebrates that feed all the bigger organisms. Without these underwater nursery grounds, which provide food and hiding places for young fish, the productivity of the Bay is compromised.
The most important thing is to make sure that you have no bare spots anywhere on your property. Turf grass, native plants, shrubs, and trees all help hang on to loose soil.