WSP01154 - Laserfiche WebLink

Home Browse Search

12 BIOLOGICAL REpORT 29 Welted Perimeter Method v~v~ , ;~'/. E :' Irlne.,onpo"'l "C : ~ :' 'E ~ ...:/ Ols.chalge (ds} Baa 1991). Addi tional methods are described by Wesche and Rechard (1980), Multiple Attribute Standard-Setting Methods All ofthe methods previously discussed result in a single stream flow value, recommended for a defined period in indi\~dual streams, These meth- ods have given rise to the term 'minimum flow.' Such standard-setting recommendations are hard to use in negotiation because too little information is available to allow an informed compromise, Much more must be done to answer the hard ques- tions during negotiation (Wilds 1985), Answering these hard . questions requires moving away from tools leading only to minimum flows, Techniques need to show the relation between the amount of habitat and stream flow, Such approaches aUow the analyst to display impacts on the resource of inter- est for any given flow, Tools that can be used to achieve this result fall into two groups. The first uses statistical analyses to correlate environmental features of a stream with fish population size, An example of this type of analysis is Wyoming's Habitat Quality Index (HQ!), described by Binns (982), An HQI is devel- oped by regressing several habitat variables against the standing crop of fish, This procedure is stream.specific, and the recommendations are re- lated to critical low flows, The second group of tools link open channel hydraulics with known elements of fish behavior, Examples include the Physical Habitat Simulation System (PHABS/Ml, as first presented by Bovee and Milhous (978) and dis- cuased again by Bovee (1982; also see Milhous et al. Fig. 2.1. Use of the wetled penmeter method to estimate inslream flows. 1984), An important explicit element of PHABSIM and HQI is an analysis of water supply, A water supply analysis should accompany any standard- setting technique to answer the question: What is the likelihood that water ..ill be available to meet the standard? Many people confuse IFIM with the Physical HABitat SIMulation System (PHABSIM). Whereas IFIM is a general problem-solving ap- proach employing systems analysis techniques, PHABSIM is a specific model designed to calculate an index to the amount of microhabitat available for different life stages a~ different flow levels, Developed from techniques used in the Pacific Northwest, PHABSIM requires the collection of field data on stream cross sections and habitat features, hydraulic simulation to evaluate habitat variables at different flows, and species suitability criteria to calculate stream characteristics with available habitat at alternate flows, Depending on the complexity of the proposed project and the complexity of the stream under study, the collec. tion of field data ranges from inexpensive and quick to costly and time consuming, Using PHABSIM enables the investigator to in. form decision makers about the impacts on fish habitat of different flows for different life stages. Attention is typically given to the life stages of fish species that are of special concern for management or that are thought to be most sensitive to change. The resulting relation between flow and habitat, generated by linking species criteria with flow-de. pendent stream channel characteristics, aids in negotiation by more clearly depicting the effect that less-than-optimum flow will have on habitat (Geer 1980), Figure 2,2 is an example of a typical habitat