Healthy streams have meandering channels and stable, vegetated banks that filter pollutants before they enter the water. Natural streams have riffles, runs and pools with varied niches for fish and other aquatic life. Canopies created by streamside trees and shrubs provide habitat for birds and mammals, keep water temperatures cool for fish, and help to prevent soil erosion.The health of streams depends on the conditions of surrounding lands – known as watersheds. Everything that occurs within its watershed will affect the stream. Many streams are injured by densely developed lands and the storm drain systems that carry stormwater runoff from streets and parking lots into the waterway. As pavement replaces vegetation, the severity and frequency of flooding and soil erosion increases, water quality declines and aquatic life is harmed.
Urban and suburban streams tend to be healthier in lightly developed portions of the watershed. Often, housing and business uses have paved over large areas of the watershed and cut down the natural vegetation. Urban streams may be straightened or hardened with concrete, which increase water velocities and erode stream banks. Other signs of damage are thick deposits of sand and silt, trash and debris, cloudy water, excess algae, exotic plants that crowd out native plants, and very low stream flows during dry months of the year.
Protecting and restoring living waters
It's likely the waters in your community pose increasing health risks - for the children who play in them, for drinking water supplies, for swimming and boating, and for the aquatic life that depends upon clean water.
Usually, little is done to keep local waters as a community asset rather than an increasing problem. For various reasons, stream care is ignored in most communities despite overwhelming public concern about the safety and health of local waters.
Much harm can be avoided by better controls and careful planning of stormwater runoff. The techniques to prevent and remedy water pollution, flooding, property damage, ecosystem destruction and loss of beneficial uses are well known. However, improvements require the cooperation of municipal officials, homeowners, developers, community groups and local businesses to succeed.