Streams

Purpose
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.
Stream
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.

Benefits
Streams perform a variety of beneficial functions, including:
  • Fish and wildlife habitat
  • Flood and storm water control
  • Groundwater recharge
  • Fish and wildlife migration corridors
  • Recreation, education, scientific study, and aesthetic values
Management Concerns
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