INSTREAM FLOW RECOMMENDATIONS 



The instream flows needed to maintain the fish populations of German 

 Gulch at their current level were quantified using the wetted perimeter/ 

 inflection point method (Nelson 1984) (see Appendix B) . Basically, the method 

 provides a range of flows from which a single recommendation is selected. The 

 flow at the high end of the range (the flow at the uppermost inflection point 

 on the wetted perimeter-flow curve) is intended to maintain the high level of 

 aquatic habitat potential. High level aquatic habitat potential is that flow 

 regime which will consistently produce abundant, healthy and thriving aquatic 

 populations. In the case of game fish species, these flows would produce 

 abundant game fish populations capable of sustaining a good to excellent sport 

 fishery for the size of stream involved. For rare, threatened or endangered 

 species, flows to accomplish the high level of aquatic habitat maintenance 

 would: I) provide the high population levels needed to ensure the continued 

 existence of that specie, or 2) provide the flow levels above those which 

 would adversely affect the specie. 



The flow at the low end of the range (the flow at the lowermost 

 inflection point on the wetted perimeter-flow curve) provides for a low level 

 of aquatic habitat potential. Flows to accomplish a low level of aquatic 

 habitat maintenance would provide for only a low population of the species 

 present. In the case of game fish species, a poor sport fishery could still 

 be provided. For rare, threatened or endangered species, populations would 

 exist at low or marginal levels. In some cases, this flow level would not be 

 sufficient to maintain certain species. 



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