Highly Innovative Hydropower Design Reduces Impact, Cuts Costs

Snohomish County Public Utility DistrictSnoPUD’s Sunset Project Design Requires No Dam, Weir or Barriers

Everett, WA — After a series of studies and design analysis, the PUD has developed a highly innovative plan for a proposed hydropower project southeast of Index. It requires no dam, weir or river barriers, which reduces construction costs by $10 million. The project could power up to 22,500 homes at maximum output.  Diverse, locally owned power sources, such as the Sunset Fish Passage & Energy Project, help make the PUD and its customers more self-sufficient, resilient and energy secure.

“We have proven success delivering low-impact hydropower projects that provide multiple benefits to our customers,” said Kim Moore, PUD Assistant General Manager of Water, Generation & Corporate Services. “This project could be a valuable addition to our portfolio. Among the low-impact projects we identified in the past seven years, it’s the lowest cost power source.”

As part of the project the PUD would make improvements to an aging, state-owned trap-and-haul facility that trucks salmon upstream above three impassible waterfalls to 90 miles of spawning habitat. The utility also is studying potential road and recreation improvements.

The PUD’s updated design modifies the water intake area and fish screens to cut excavation needs in half. It also reduces construction time by an estimated six months. In addition, more efficient turbines at a proposed powerhouse would increase annual energy production.

The “No-Dam” Design

The no-dam design is possible due to the unique geography of the South Fork Skykomish River. Upstream from Sunset Falls, the river turns sharply – a complete 180 degrees – creating a deep pool of water, which can accommodate an underwater intake structure. The water for the project would flow from the upstream intake to an underground tunnel through solid bedrock a half-mile to the PUD powerhouse. Sufficient water would remain in the river for fish, aesthetics and recreation.

The PUD cites several key benefits of its hydropower projects. They are non-polluting, local renewable sources with no heat or noxious gas releases. Their generating output coincides with the times of the year when energy is needed the most. Small hydropower projects typically are sited at or above waterfalls or impassible barriers to minimize fish issues. Hydropower facilities also have long lives – many operate for 100 years or more.

Innovative Hydro Design

For decades, the bulk of the PUD’s energy has come from Pacific Northwest hydropower. The PUD has proven success operating its projects in a way that protects fish, wildlife, recreation and community resources. The utility has garnered numerous awards for its hydropower operations, including from the Puget Sound Regional Council, Renewable Energy World and the American Society of Civil Engineers.

In addition to the Sunset Project, the PUD is assessing two other local hydropower projects above Snoqualmie Falls near North Bend. These projects are the lowest cost renewable energy sources available locally, better in price than wind, solar, tidal and biomass/biogas.

Project Survey

Starting May 1, the PUD will survey customers about the Sunset Fish Passage & Energy Project. The survey will cover public access, recreation, aesthetics and other background information. Visit www.snopud.com/sunset in May to take the survey. Prize drawings for restaurant gift cards will be awarded.  The utility encourages customers to participate.