Determining the minimum instream flow for hydro peaking projects

A new analytical technique is available for quantifying and predicting the effect that a proposed hydro peaking operation, or a change in an existing project's operation, will have on physical habitat for aquatic populations downstream of the project. The technique, known as the dual flow analysis, is based on elements of the US Fish and Wildlife Service's Physical Habitat Simulation System (PHABSIM). PHABSIM is used to calculate the physical habitat for aquatic organisms in a stream. The assumption behind the development of this technique is that if the effects of a proposed project on physical habitat are known, one can better understand the effects on aquatic organisms. Thus, a defensible selection of an instream flow requirement can be made. The technique was developed as a result of a joint study by the US Fish and Wildlife Service and Niagara Mohawk Power Corp. at the 26.4-MW Bennetts Bridge and the 7.8-MW Lighthouse Hill developments on the Salmon river in upstate New York.