Small dam, major power

  • By Bill Sheets Herald Writer
  • Wednesday, October 19, 2011 12:01am
  • Local News

SULTAN — This winter, a little more of the power flowing into Snohomish County homes will be locally grown.

The Snohomish County Public Utility District has officially opened its new mini-dam and powerhouse on Youngs Creek south of Sultan.

The $29

million project, south of Sultan, is expected to produce enough electricity on average for about 2,000 homes. The dam, 12 feet tall and 65 feet across, is the first new one in the state in more than a quarter of a century, according to the PUD.

The project is easy on the environment and helps the utility’s goals of increasing its power independence and diversifying its sources, officials say.

“Considering we’re a growing utility, this project makes sense in terms of gaining more local control over our energy supply,” said Scott Spahr, senior engineer for water resources and generation for the PUD.

This could be just the beginning of small hydropower projects for the PUD. The utility has received permits to study placing dams on Hancock and Calligan creeks on the I-90 corridor in King County. The PUD also has applied to the Federal Energy Regulatory Commission for a permit to study building a small dam near Sunset Falls on the Skykomish River near Index.

Environmental groups have concerns about more dams, however small the structures may be, and are watching the PUD closely, said Tom O’Keefe of Seattle, Northwest stewardship director for American Whitewater, a national advocacy group for leaving rivers in their natural state.

“We’re raising general concerns with the approach the PUD is taking here, of developing new hydropower and building new dams on rivers,” he said.

Currently, the utility district buys about 92 percent of its electricity from other agencies, most of it hydroelectric power from the Bonneville Power Administration.

The PUD hopes to reduce that percentage and diversify its power sources as much as possible.

While the project will serve only about two-thirds of 1 percent of PUD customers, the utility also is studying the other dams, exploring geothermal and tidal power, and offers discounts for people using solar power.

The PUD already owns and operates two dams, one large and one small. The 640-foot-long, 263-foot-high Culmback Dam at Spada Lake produces enough energy to serve nearly 36,000 homes. The reservoir also provides much of the county’s drinking water.

In 2008, the PUD bought a tiny, 6-foot-tall dam and powerhouse on Woods Creek near Monroe from a private utility company for $1.1 million. It was built in 1982.

The Youngs Creek project took about three years to build. It consists of two main parts, a dam and a powerhouse. The dam creates a quarter-acre pond. An underground pipeline carries water alongside the creek down to the powerhouse, 3 miles downstream from the dam. There the water pushes a turbine that drives a 7.5-megawatt generator before it returns to the creek.

The 920-foot drop in elevation between the dam and powerhouse helps create the force to spin the turbine, Spahr said. An 8.1-mile-long underground and overhead transmission line connects the powerhouse to the Sultan substation.

The turbines will operate at their highest capacity in winter when water flow is heaviest and the power need is greatest. In those rainy months, it will be capable of tripling its average output, creating enough power for 6,000 homes. In the drier months, it will operate at lower capacity or shut off entirely.

The powerhouse is located 1½ miles above a steep waterfall that’s impassable to salmon, so the project will not affect their ability to spawn, officials say.

Trout live in the water around the dam, but many of them already are separated from each other by natural barriers such as small waterfalls. They still thrive, so the dam is not expected to cause a problem, Spahr said.

“It’s not affecting flow, it’s not affecting stream temperature,” he said.

Still, Rich Bowers of Bellingham, Northwest coordinator for the Hydropower Reform Coalition, says the cumulative effect of small dams is not worth the power they generate.

“We don’t take issue with Youngs Creek individually,” he said. Overall, however, “low power is a more appropriate name for these dams, which provide little generation, have high resource impacts, do little to help the state diversify its energy mix, and lead to additional dams in a state where rivers and streams are already highly stressed.”

Spahr said the PUD communicated with Bowers’ group, among others, during the planning for Youngs Creek. Eight government agencies and the Tulalip Tribes signed off on the project, he said.

Spahr said microdams are more economical than other environmentally friendly sources of energy such as solar or wind power.

“The best way to make (small hydro) as low impact as possible is to pick the right site,” he said.

Because of the effect on fish, “I think the days of building big dams like you see on the Columbia (River) are over,” Spahr said.

Six dams have been built in the state since the early 1980s, and they’re all roughly the size of Youngs Creek or smaller, according to the state Department of Fish and Wildlife.

The Youngs Creek project originally was planned and then shelved by Puget Sound Energy in the 1990s. The property was bought by a small private utility, which sold it to the PUD about three years ago for $750,000, Spahr said.

The Youngs Creek project is financed with bonds. The project won’t have an immediate effect on ratepayers’ bills, but officials say in the long run it could help reduce rates by reducing the utility’s need to buy power from other sources.

Bill Sheets: 425-339-3439;

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