Urban stormwater runoff often creates muddy streams. Note the difference in turbidity between the main channel of Rock Creek, and the little tributary coming in from the right.
Photographer: Sam Sheline, courtesy of NatureServeStormwater runoff increases turbidity. The fast-flowing water, sometimes already muddied from construction site runoff, erodes more sediment from the banks. The extra sediment suffocates aquatic creatures, prevents sunlight from reaching aquatic plants, and clogs up the protected spaces between rocks in shallow riffles that shelter fish eggs, juvenile fish, and aquatic insects.