Streams are powerful erosional and depositional forces that can continually change and influence the shape of a landscape. Streamflow has a significant capacity to effectively erode and transport rocks, sediments, debris, and nutrients toward river valleys or out to marine shorelines. Erosion varies considerably depending on the volume, speed, and turbulence of streamflow, as well as the stream gradient erosion resistance of the underlying bed rock or sediments.
Variation in stream composition and form, as well as adjacent and overhanging riparian vegetation, is crucial for healthy fish and wildlife habitat.
Pools and side channels provide sheltered areas for aquatic wildlife
(spawning, hiding, migratory resting areas, etc.). Overhanging trees and
riparian vegetation provide habitat and protection for terrestrial
wildlife and water temperature control for aquatic life. Well vegetated
riparian areas can also provide bank stabilization properties, pollutant
filtration, and a source of large woody debris.
Streams perform a variety of beneficial functions, including:
Fish and wildlife habitat
Flood and storm water control
Fish and wildlife migration corridors
Recreation, education, scientific study, and aesthetic values
Development can degrade a stream’s wildlife habitat and water quality, undermining its values and functions by:
Increasing stormwater runoff and flooding frequency
Contributing increased levels of sediment, nutrients and pollutants
Increasing stream turbidity which can reduce the light and oxygen necessary for plant and animal life
Increasing the volume and velocity of stream flows which can scour
stream beds and decrease stream habitat function and diversity
Removing vegetation along stream banks
Warming stream temperatures
Disconnecting the stream from its floodplain and associated wetlands