Runoff from these areas will continue to degrade coastal waters. To protect surface water and ground water quality, urban development and household activities must be guided by plans that limit runoff and reduce pollutant loadings. Communities can address urban water quality problems on both a local and watershed level and garner the institutional support to help address urban runoff problems. How Urban Areas Affect Runoff Increased Runoff . The porous and varied terrain of natural landscapes like forests, wetlands, and grasslands trap rainwater and snow melt and allow it to filter slowly into the ground.
Water remains at the surface, accumulates, and runs off in large amounts.
When leaving the system and emptying into a stream, it erodes stream banks, damages stream side vegetation, and widens stream channels This will result in lower water depths during non-storm periods, higher than normal water levels during wet weather periods, increased sediment loads, and higher water temperatures. Native fish and other aquatic life cannot survive in urban streams severely impacted by urban runoff. Increased Pollutant Loads . Sediments and solids constitute the largest volume of pollutant loads to receiving waters in urban areas. When runoff enters storm drains, it carries many of these pollutants with it.