Directions for PHWH Evaluation

Directions for PHWH Evaluation Directions for Evaluating Primary Headwater Streams Have in front of you the flowchart - Assigning Aquatic Life Use Designations before proceeding (item #13 in Module 2)  
  1. Determine the maximum pool depth, and the size of the drainage area
    1. If the maximum pool depth is greater than 40cm, and the drainage area is greater than 1 square mile then you have answered yes to step #1. Go to step 2.
    2. If the pool depth is not greater than 40 cm, and the drainage area is not greater than 1 square mile, you have answered no to step #1.  Go to step 3.
 
  1. Perform a QHEI and evaluate for non PHWH designated use(s). 
    1. If other uses are appropriate go to step 4.
    2. If other uses are not appropriate go to step 3.
 
  1. Perform an HHEI and evaluate scores to determine potential classification. 
    1. If the channel is natural go to step 5.
    2. If the channel is not natural, go to step 9.
 
  1. You are finished with the flow sheet.  You now need to complete evaluation for proper designated use(s) for streams that are larger streams and not PHWH stream - see Manual.
 
  1. Look at the HHEI score:
    1. If the score is greater than 70 this is Class III PHWH.  You are finished with the flow sheet.
    2. If the score is under 30 then this is Class I PHWH. You are finished with the flow sheet.
    3. If the score is under 70 but over 30 go to step 6.
 
  1. The stream is flowing AND the watershed area is less than 0.1 square miles:
    1. If yes, this is Rheocrene flow.  See the Manual for evaluating the biology.  You are finished with the flow sheet.
    2. If no, go to step 7.
 
  1. Look at the HHEI score:
    1. If the score is under 50, this is Class II PHWH.  You are finished with the flow sheet.
    2. If the score is above 50 go to step 8.
 
  1. Estimate the percentage of stream substrate composed of bedrock, boulder, boulder slabs and cobble:
    1. If the percentage of these substrates is under 20% this is Class II PHWH.  You are finished with the flow sheet.
    2. If the percentage of these substrates is over 20%, this is a Class III PHWH.  You are finished with the flow sheet.
 
  1. Look at the HHEI score
    1. If the score is under 30 this is a Modified Class I PHWH.  You are finished with the flow sheet.
    2. If the score is greater than 30 but under 70, this is a Modified Class II PHWH.  You are finished with the flow sheet.
    3. If the score is greater than 70 then you need to evaluate the stream for the biotic community.  You are finished with the flow sheet.