Evaluation of the instream flow incremental methodology by U.S. Fish and Wildlife Service field users

This paper summarizes results of a survey conducted in 1988 of 57 U.S. Fish and Wildlife Service field offices. The purpose was to document opinions of biologists experienced in applying the Instream Flow Incremental Methodology (IFIM). Responses were received from 35 offices where 616 IFIM applications were reported. The existence of six monitoring studies designed to evaluate the adequacy of flows provided at sites was confirmed. The two principal categories reported as stumbling blocks to the successful application of IFIM were beliefs that the methodology is technically too simplistic or that it is too complex to apply. Recommendations receiving the highest scores for future initiatives to enhance IFIM use were (1) training and workshops for field biologists; and (2) improving suitability index (SI) curves and computer models, and evaluating the relationship of weighted useable area (WUA) to fish responses. The authors concur that emphasis for research should be on addressing technical concerns about SI curves and WUA.