* Provide adequate habitat for aquatic organisms

* Maintain suitable water temperatures, dissolved oxygen, and water chemistry

* Maintain water table levels in floodplain, soil moisture for plants

* Provide drinking water for terrestrial animals

* Keep fish and amphibian eggs suspended

* Enable fish to move to feeding and spawning areas

* Support hyporheic organisms (living in saturated sediments)

Frequency of extreme low flows during each water year or season

Mean or median values of extreme low flow event:

* Duration (days)

* Magnitude (minimum flow during event)

* Timing (Julian date of event)

* Enable recruitment of certain floodplain plant species

* Purge invasive, introduced species from aquatic and riparian communities

* Concentrate prey into limited areas to benefit predators

Frequency of high flow pulses during each water year or season

Mean or median values of high flow pulse event:

* Duration (days)

* Magnitude (maximum flow during event)

* Timing (Julian date of peak flow)

* Rise and fall rates

* Shape physical character of river channel, including pools, riffles

* Determine size of streambed substrates (sand, gravel, cobble)

* Prevent riparian vegetation from encroaching into channel

* Restore normal water quality conditions after prolonged low flows, flushing away waste products and pollutants

* Aerate eggs in spawning gravels, prevent siltation

* Maintain suitable salinity conditions in estuaries

Frequency of small floods during each water year or season

Mean or median values of small flood event:

* Duration (days)

* Magnitude (maximum flow during event)

* Timing (Julian date of peak flow)

* Rise and fall rates

Applies to small and large floods:

* Provide migration and spawning cues for fish

* Trigger new phase in life cycle (for example, insects)

* Enable fish to spawn in floodplain, provide nursery area for juvenile fish

* Provide new feeding opportunities for fish, waterfowl

* Recharge floodplain water table

* Maintain diversity in floodplain forest types through prolonged inundation (for example, different plant species have different tolerances)

* Control distribution and abundance of plants on floodplain

* Deposit nutrients on floodplain

Frequency of large floods during each water year or season

Mean or median values of large flood event:

* Duration (days)

* Magnitude (maximum flow during event)

* Timing (Julian date of peak flow)

* Rise and fall rates

Applies to small and large floods:

* Maintain balance of species in aquatic and riparian communities

* Create sites for recruitment of colonizing plants

* Shape physical habitats of floodplain

* Deposit gravel and cobbles in spawning areas

* Flush organic materials (food) and woody debris (habitat structures) into channel

* Purge invasive, introduced species from aquatic and riparian communities

* Disburse seeds and fruits of riparian plants

* Drive lateral movement of river channel, forming new habitats (secondary channels, oxbow lakes)

* Provide plant seedlings with prolonged access to soil moisture