Striving for Balance Between Environmental Flows and Hydroelectric Operations: Case Study – Henry M. Jackson Hydroelectric Project, Sultan River, Washington

The Henry M. Jackson Hydroelectric Project (FERC 2157) is located on the Sultan River, approximately 38 km east of Everett, Washington.  The 112-megawatt facility, completed in 1984, produces 4 to 5 percent of the Snohomish County Public Utility District No. 1 (District's) power needs. In addition to generating power, the project provides recreation, enhances fish and wildlife habitats, provides an element of flood control and an abundance of drinking water.  On December 1, 2005, the District filed an Preliminary Application Document and intent to seek a new license with the Federal Energy Regulatory Commission (FERC).  The primary environmental flow issues associated with relicensing of the project included: establishing a balanced water management and flow regime that considers hydro generation, water supply, habitat, recreation, and flood control needs; determining appropriate periodic high flows that mimic natural fluvial processes; facilitating upstream and downstream passage of anadromous fish; restoring spawning and rearing habitats for salmonids; and providing flows for whitewater recreation. From 2006-2009, the District commissioned a series of studies to evaluate the above issues.  These included among others, fish and habitat surveys, an instream flow assessment (PHABSIM), a fluvial geomorphologic survey, water quality monitoring and modeling, and a whitewater flow study. Habitat-flow relationships derived from the PHABSIM analysis were linked with a Project reservoir and river operations model that considered water allocation for power generation, the City of Everett's (City) municipal water supply, and instream flows.  This allowed for the evaluation of discrete flow release scenarios with respect to benefits to fish species/lifestages versus tradeoffs in power generation and water supply. The results from this analysis and from other resource studies were instrumental in the development and submittal to the FERC on October 14, 2009 of a Settlement Agreement signed by the District, City, resource agencies, tribes and non-governmental organizations, the City of Sultan, and Snohomish County. This paper highlights the major studies relied upon by the District to facilitate concurrence on a set of environmental flows that became part of the Settlement Agreement.