PPT Slide
In many highly urbanized areas, natural streams have been channelized to speed runoff along, but these fail to provide any habitat value.
Copyright 2000, Center for Watershed Protection
Notes:
When impervious cover exceeds 40%, engineers are often called in to channelize or stabilize stream channels. In the past, concrete channels were used to speed runoff further along, but there is no habitat value to these engineered channels.