City Light to Replace Newhalem Penstock Saddles

Seattle City Light will be replacing 52 deteriorating, wooden saddles that support the Newhalem Penstock with new, cast-in-place concrete saddles. These new saddles will provide structural stability and protect the integrity of the penstock.

The penstock is a pipe that delivers water from the creek to the hydro turbines that are located inside the Newhalem powerhouse. The water turns the turbines, which eventually produces electricity.

The Newhalem Penstock is located on the south bank of the Skagit River in the town of Newhalem, WA. The project is within the Ross Lake National Recreation Area, which is part of the North Cascades National Park Complex.

This project is expected to start in mid-July 2016 and last approximately 12-14 weeks. Daily work hours are from Monday through Friday, 7 a.m. to 6 p.m. Weekend work is possible.

Map of the construction work area

During construction, trucks will use the access road to Loop C and Group Sites A and B of the Newhalem campground. All park facilities will remain open. At times, a helicopter may be used to deliver materials and concrete to the site. Park users may encounter additional noise. The Trail of the Cedars will also be open during construction. It will be rerouted around the construction site.

For more information, customers can contact Lisa Williams, Project Manager at (206) 733-9268 or

This information is also available on the City Light construction website:

Diablo Lake to Be Lowered for Construction Work

Diablo Lake

To continue construction of a new heavy barge landing dock, Seattle City Light will lower the water level of Diablo Lake at the utility’s Skagit Hydroelectric Project by up to 10 feet. The drawdown will start on Sept. 10 and take up to six days to complete. Low lake levels are scheduled to last until Nov. 5.

Construction workers install a rockery fence above the site for the new barge landing.

With lower water levels, the boat ramp and fishing dock at Colonial Creek Campground will not be usable. Skagit Tours and the Diablo Lake ferry service will operate as scheduled though passengers should be prepared to walk much steeper ramps at the docks.

This $1.5 million project is one of the final phases of work needed to replace facilities destroyed by a 2010 rockslide.  The project must be completed to allow for the delivery of six new transformers to Ross Powerhouse scheduled for 2016.

Seattle City Light is the 10th largest public electric utility in the United States. It has some of the lowest cost customer rates of any urban utility, providing reliable, renewable and environmentally responsible power to about 750,000 Seattle area residents. City Light has been greenhouse gas neutral since 2005, the first electric utility in the nation to achieve that distinction.

Salmon habitat preserved by City Light

City Light recently purchased 40 acres of Day Creek Slough in the Middle Skagit River.

The property is one of the most productive habitats of juvenile salmonid in the area, and will provide refuge and a safe place for rearing for salmon and steelhead. The purchase has been added to the 274 acres of land bought through the Fisheries Settlement Agreement mitigation funds as well as over 3,288 acres of habitat conservation lands City Light currently owns.

The property was acquired with City Light funds under the Skagit River Hydroelectric Project Revised Fisheries Settlement Agreement, and also with funds under the city’s Endangered Species Early Action Program.




Seattle City Light Biologist’s Co-Author Research Paper on Chinook Salmon in Skagit River

Seattle City Light Biologists Ed Connor and Dave Pflug co-authored a research paper on Chinook Salmon in the Skagit River that was recently published by the scientific journal Transactions of the American Fisheries Society.


“The paper, titled “Abundance, survival, and life history strategies of Juvenile Chinook Salmon in the Skagit River, Washington,” investigated the influence of river flows in the survival of juvenile Chinook salmon. It found that fish management flows from City Light’s Skagit River Hydroelectric Project, particularly reductions in peak flows, have improved juvenile Chinook survival in the river downstream of the project.”

The paper identifies “potential actions for conserving Chinook Salmon Oncorhynchus tshawytscha in the Skagit River.” Seattle City Light contributed to the funding of this research that observed river flows as well as freshwater rearing patterns, spawning and more regarding the six recognized populations of Chinook salmon. The research demonstrated the importance for Chinook salmon survival of managing river flows to avoid peak flow events.  Furthermore, Chinook juveniles exhibiting extended freshwater rearing periods would benefit from additional restoration of freshwater rearing habitats.

Another conclusion derived from the research is that Chinook salmon juveniles with extended freshwater requirements could be enhanced with additional increases in the quality and quantity of rearing habitat, especially backwater areas, natural banks and off-channel habitat in the middle and lower portions of the Skagit River.

Seattle City Light is actively engaged in promoting healthy salmon runs on the Skagit River as part of its operations of the Skagit Hydroelectric Project. City Light’s three dams were built above natural barriers to fish passage and the utility operates them to manage river flows to support spawning runs and juvenile fish. Staff biologists monitor river conditions and research opportunities to enhance fish populations on the river.



Early Snowpack Near Normal for Seattle City Light Hydroelectric Dams

A story in this morning’s Seattle Times about snowpack conditions in the Cascades generated several questions about the amount of snow that will eventually support Seattle City Light’s hydroelectric dams once it melts.

The key to the answer is location, location, location.

Our friends at Seattle Public Utilities collect our area’s drinking water from the Cedar River watershed east of Seattle. Snowpack levels there are significantly below normal.

Seattle City Light’s large hydroelectric dams are located on the Pend Oreille River in Northeast Washington and the Skagit River northeast of Seattle. Those dams depend on snowpack in the Rocky Mountains of Montana and the North Cascades where conditions are close to normal for this time of year.

The water year starts in October, so it is still early in the measurements. A lot can change between now and May. Remember that conditions were very dry a year ago until March brought heavy snows. Our staff monitors those conditions so we can adjust our operations as needed based on how much power we expect to be able to generate.

Here’s a look at the snowpack levels measured across the region. 


Pacific Northwest snowpack levels.