Snoqualmie Falls Hydroelectric Project

Posted by on Mar 11, 2010 | No Comments


The Snoqualmie Falls Hydroelectric Project is Puget Sound Energy’s oldest power-generating operation and the world’s first completely underground power plant. More than a century after its construction, the facility still produces clean, cost-effective electricity for PSE customers. In addition, the hydroelectric project’s public park and trails have for decades been one of the Pacific Northwest’s most popular scenic destinations, drawing approximately 2 million visitors annually to view the majestic, 270-foot waterfalls.

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Along the Snoqualmie River in Snoqualmie, Wash., about 30 miles east of Seattle

Current Hydropower Features

  • Plant 1 powerhouse, built in 1898-1899 just above Snoqualmie Falls inside a bedrock cavity 270 feet below ground; plant’s five power-generating units have 11.9 megawatts (MW) of generating capacity
  • Plant 2 powerhouse, built in 1910 a quarter-mile downstream from the falls and expanded in 1957; plant’s two generating units have 32.5 MW of generating capacity
  • A small diversion structure, ranging about 4 to 18 feet in height, just upstream from Snoqualmie Falls; structure helps direct water to powerhouses and boost their power-generation capacity
  • Steel penstocks (pipes) and concrete-lined tunnels for carrying river water to powerhouses
  • Average power output sufficient to meet the electricity needs of more than 20,000 households

Public Accommodations

  • Snoqualmie Falls Park, a two-acre site containing picnic areas, restrooms, and cliff-side observation areas for viewing Snoqualmie Falls
  • A 10-acre recreation area with forested wildlife habitat, hiking trails, a kayak / canoe launching area, and a riverside boardwalk and observation platform for viewing Snoqualmie Falls
  • Parking space for tour buses and approximately 450 cars

Project License

  • Project’s federal operating license renewed June 2004 by the Federal Energy Regulatory Commission (FERC), authorizing another 40 years of hydropower generation
  • License amendment issued June 2009 by FERC, primarily for planned upgrades at Plant 1

Redevelopment Plan

Under the project’s federal operating license, PSE will be making substantial upgrades and enhancements to its power-generating infrastructure and public facilities, including:

  • New generators, water-intake structures and penstocks at Plant 1 and Plant 2, boosting project’s authorized output of 44 MW to a 54 MW capacity
  • Replacement of existing diversion structure with 2-foot-lower apparatus; new structure and riverbank work will ease upstream flooding in city of Snoqualmie with virtually imperceptible downstream effects
  • Within PSE’s existing park boundaries, redevelopment work will include improved hiking trails, enhanced park accommodations and landscaping, new interpretive and educational signage, improved river access and parking for boaters, and new lighting and fencing
  • Preservation and display of historical artifacts, photos and records
  • Habitat improvements for fish and wildlife
  • Increased minimum river flows over Snoqualmie Falls during summer months

Redevelopment Time Line

Major construction to commence in fall 2009 and continue, in stages, through 2014


Jason Van Nort
Government and Community Relations Manager
Puget Sound Energy