Stream Permanency Key

Ephemeral Stream
Flow only briefly after spring snowmelt or heavy rain, drying within days to a few weeks.
Stream bed may be defined, but banks are usually absent or not well-formed.
Evidence of flow may exist as a faint path on the forest floor.
Terrestrial plants often grow on the stream bottom.
Aquatic invertebrates are absent.
When uncertain, classify as intermittent rather than ephemeral.

Intermittent Stream
Flow for several weeks during wet seasons, e.g., after snowmelt or rain.
Streambed is defined, but banks may be absent or discontinuous.
Erodible, sorted material may be present on the stream bottom.
Terrestrial plants may grow on the streambed.
Aquatic invertebrates are absent or rare.
When uncertain, classify as permanent rather than intermittent.

Permanent Stream
Flow most of the year; may stop only during drought.
Streambed is defined and often contains sorted, erodible material.
Banks are continuous and well-formed.
Terrestrial plants are usually absent on the stream bottom.
Aquatic invertebrates are common.

Streambed defined? → No → Ephemeral
Continuous banks? → No → Intermittent
Terrestrial plants absent + invertebrates common → Permanent

Ephemeral
Flows only briefly after snowmelt or rain; dries in days–weeks.
Banks absent or poorly formed.
Terrestrial plants grow on streambed.
Aquatic invertebrates are absent.

Intermittent
Flows for several weeks in wet seasons.
Streambed defined; banks absent or discontinuous.
Erodible material may be present.
Terrestrial plants may grow on the bottom.
Aquatic invertebrates are absent or rare.

Permanent
Flows most of the year; may stop in drought.
Streambed defined with sorted, erodible material.
Banks continuous.
Terrestrial plants absent..
Aquatic invertebrates are common.