Primary Headwater
Habitats (PHWH)
The Basics - What is a Primary
Headwater Stream?
Characteristics:

A Watercourse1 with:
A defined BED2 and BANK3
Either continuous4 or periodic5
FLOWING water
A drainage6
generally less than one square mile
Deepest pools7 < 40cm
Widely divergent8 communities
based upon in- stream Biology
Why Classify PHWH Streams?
To provide standardized
information for making
decisions affecting water
quality in primary
headwater streams
To help maintain the
quality of water and
biological communities in
larger streams, lakes and
wetlands
The turbid PHWH stream at the top
flows into the clear PHWH stream below
degrading downstream waters to the left
A traditional stream classification system:
Classification by the Stream Continuum Concept
Ohio EPA’s
Classes of PHWH Streams
Class I – EPHEMERAL1 stream,
normally dry channel with little to no aquatic life;
native fauna when flowing
Class II – INTERSTITIAL2 to
PERENNIAL3 moderately diverse
aquatic life with native fauna4 adapted to
warm water
Class III –diverse aquatic life adapted to
cool/cold PERENNIAL flowing water
Stream Flow Types
Ephemeral flow = Channel
dry phase present annually, flow during rain or snow melt ,
permanent pools absent
Class I
PHWH Streams
Characteristics





Flow - ephemeral
Channel1 - dry phase present annually,
flow during rain or snow melt
Permanent pools - absent
Aquatic life - absent or present seasonally
Aquatic life - diversity low
Class I PHWH Stream - Example
Natural channel, Geauga Co
More Examples of Class I (click)
Class II
PHWH Streams
Characteristics





Flow – intermittent
Channel – no continuous channel - only
shallow groundwater connection between
pools
Permanent pools - present most years
Aquatic life - abundance high
Aquatic life diversity - moderate and warm
water adapted
Class II PHWH Stream - Example
Natural channel, Geauga Co.
More Examples of Class II (click)
Class III
PHWH Streams
Characteristics




Flow - perennial, deep groundwater
Channel - present
Permanent pools - present
Aquatic life diversity1 & abundance Presence of one or more of the following at all times:
2
 Obligate aquatic salamanders
 Cold water or pioneering fish species
3
 Cool water adapted benthic macro-invertebrates
Class III PHWH Stream - Example
Delaware Co.
More Examples of Class III (click)
Quick Quiz
What class PHWH
stream is this?
What characteristics
did you use to classify
the stream?
Quiz Question 2
What PHWH Stream
Class is shown here?
How do you know you
have chosen the
correct class of
PHWH stream?
Glossary
Terms as used for PHWH streams
Bank- The lateral confines of a stream.
Bed- The bottom of the stream. The physical boundary of normal water flow.
Benthic- Organisms that live on the bed (bottom) of the stream.
Channel- The course of the bed of a stream, river, or waterway.
Continuous- Uninterrupted flow.
Continuum-.
Divergent-.
Diverse- Different kinds, characters, or forms.
Drainage- Water flowing off and from an area.
Ephemeral- Usually flowing for only a short amount of time, dry at some time annually.
Fauna- Animals of a given area.
Intermittent- Flow that stops or ceases for a period of time.
Interstitial- Flow interrupted by dry channel (sub-surface between pools).
Obligate- Able to exist or survive only in a particular environment.
Perennial- Flowing year round.
Periodic- Happening over regular intervals.
Pioneering Pools- A relatively deep, slow flowing or still place in a stream.
Watercourse- Channel.
Watershed- Region or area that drains into a given stream, river, or water body.