REVIEW AND ANALYSIS OF METHODS FOR QUANTIFYING INSTREAM FLOW REQUIREMENTS¹

Abstract

Present guidelines for selecting a method to determine instream flow requirements and evaluating the validity of the results from a particular method are insufficient. This paper contributes to the efforts of researchers to develop a guide and critique for instream flow methods. A review of instreani flow methods and recommendations for their application is supplemented by a summary of a comparison of four independent analyses. The four analyses: the Physical Habitat Simulation System approach of the Instream Flow Incremental Methodology by the U.S. Fish and Wildlife Service, the Montana Method by Tennant, and two methods by Orsborn (Maximum Spawning Area Flow and Maximum Spawning Area) represent resource intensive and simplistic data collection and analysis methods. Each analysis was used to independently determine flows to support spawning by chinook salmon (Oncorhynchus tshawytscha) in Willow Creek, Alaska. Results of these analyses indicate that each method can be used independently or collectively to generate instream flow recommendations, if calibrated to the site or area studied. Once adjusted to the species and basin of interest, methods similar to the Montana and two Orsborn methods should be used to determine flow recommendations for areas where competition for water is minimal. The Instream Flow Incremental Methodology or similar methods should be applied when competition for water is keen or when detailed evaluations of the responses of species/life phases to flow variations are required.

Instream flow methods: a comparison of approaches

“…The discussion of flow assessment methods has been extensive, without any real resolution (e.g. Stalnaker and Arnette, 1976;Wesche and Rechard, 1980;Schuytema, 1982;Karim et al, 1995;Trihey and Stalnaker, 1985;Estes and Orsborn 1986;Morhardt and Altouney, 1986;Richardson, 1986).…”

Evaluating the impacts of instream flow on water supply for municipal and irrigation use

“…However, its accuracy is questionable and does not consider the IF for species/life phase habitat requirements. Also, QAA does not describe the short‐ or long‐term changes in flow rates, seasonal variability or channel geometry (Estes and Orsborn, 1986). Accordingly, in this study, seven of the classifications used as the criteria of the Montana method are used to check and confirm the 1930–1997 new generated IF data.…”

“…From the early 1960s, a number of methodologies, such as historical (hydrological) flow, hydraulic rating, habitat rating and holistic methods, have been proposed for evaluating environmental IF. These methods are reviewed and applied to several areas (Estes and Orsborn, 1986; Garn, 1986; Karim et al ., 1995; Lamb, 1995; Cardwell et al ., 1996; Jowett, 1997; Yuan et al ., 2006; Caissie et al ., 2007; Song et al ., 2007; Deitch et al ., 2009). Several techniques are also presented for quantifying environmental IF by economic costs (Loomis, 1998; Ward and Booker, 2003).…”

A comparison of desktop hydrologic methods for determining environmental flows

“…In this type of modification, the timing window for each flow threshold is adjusted depending on the fish life histories and ecological information for the target stream. This approach is described by Estes and Orsborn (1986) and Ptolemy and Lewis (2002). Richter et al (2012) reviewed several case studies that developed and applied risk thresholds for water management, and made a case for a "presumptive standard" to be used when site-specific standards are absent.…”