Impervious Cover

Habitat for fish is severely impacted in watersheds where over 15% of the land is covered by impervious material such as pavement or roofs. Impervious cover results in polluted runoff, higher air and water temperatures, and reduced recharge of rainfall into the soils that would otherwise feed clean and cool groundwater baseflow to streams and rivers. Percent impervious cover is also an indicator of habitat integrity or disturbance. Calculations for this indicator are based on analysis of the land area in each river segment.