Instream Flow Assessments for Hydropower Applications in California

A key effect caused by dams and water diversions on aquatic species and habitats is the reduction of instream flow. The term “instream flow” refers to the amount of water flowing in a natural stream or river that is needed to sustain aquatic species and habitats.  Hydropower operations affect instream flows mainly through the retention of water behind dams and/or the diversion of water from streams or rivers. In general, increases in instream flows downstream of a hydropower facility means reduced hydropower generation.  Because of the large number of hydropower plants that will be undergoing the Federal Energy Regulatory Commission’s (FERC) relicensing process in the near future, hydropower impacts on aquatic ecosystems are receiving increased scrutiny.  Approximately 5,000 megawatts of hydropower (one-third of the state’s installed hydropower capacity) in California will undergo relicensing by 2015.  One of the most contentious topics for projects during the relicensing process will be the determination of the appropriate instream flows.

 The mission of the Public Interest Energy Research, Environmental Area (PIEREA) program is to develop cost-effective approaches for evaluating and resolving environmental effects of energy production, delivery, and use in California, and explore how new electricity applications and products can solve environmental problems.  PIEREA's goal is to resolve impacts from electricity generation, transmission, and use.  The purpose of this program is to conduct research that identify and reduce adverse impacts on aquatic species and habitats from instream flow variations caused by the operation of California hydropower facilities.  Research funds shall be awarded in the form of requests for proposals, sole source contracts, and graduate research.