What is a "good quality" stream?

Before we talk more about poor water quality, it is important to understand the characteristics of a good quality stream.  Natural streams in undisturbed settings have a number of characteristics that are illustrated below:



Good streams have vegetation along the banks that hold down soil and shade the stream.
Good streams have vegetation along the banks that hold down solids and shade the stream. This area is called the riparian zone.
 
 
 
 
 
Good streams "meander" or have curves
Good streams meander - they have natural curves that slow down the water so that it will not erode the banks.
Good streams have a rocky bottom or substrate that is "clean"
Good streams have a rocky bottom or substrate that is "clean".
Good streams support of diversity of aquatic life
Good streams support a diversity of aquatic life including fish and macroinvertebrates (aquatic insects).
Streams through agricultural areas are often straightened
Streams through agricultural areas are often straightened.  This removes habitat and results in water running faster and causing more erosion of the bed.
Urban streams are often straightened in channelized
Urban streams are often straightened and channelized.
Removing vegetation causes heavy sediment loads
Removing vegetation causes heavy sediment loads which smothers bottom animals and plants.
Industrial pipes discharge wastes directly to streams
Industrial pipes discharge wastes directly to streams.