Seattle City Light Lowering Diablo Lake for Boat Landing Repairs

Seattle City Light is making repairs to boat landings near the Ross Powerhouse at the utility’s Skagit Hydroelectric Project that will require lowering Diablo Lake.

A 2010 rockslide destroyed a landing for heavy-haul barges that carry heavy equipment to and from the Ross Powerhouse.  Six transformers now in use at the powerhouse are due for replacement, starting in 2016. A light duty landing survived and has been in use since the rockslide, however, it requires a sharp turn that the semi-tractor trailers that will transport the 80-ton replacement transformers cannot make.

A pickup parked near the National Park Service boat landing was hit by the 2010 rockslide.

The $1.5 million project will install a new barge landing and swap locations for two docks used by the National Park Service and a ferry that carries visitors to Ross Lake.

To avoid environmental impacts on the lake, construction needs to be done above the water line. City Light plans to lower the lake level either May 21 or 26. Construction will continue through June 15, when the utility will return the lake to its regular operating level.

A similar draw down will be done, starting Sept. 15 through Nov. 1 to complete the work.  If needed, another draw down may be scheduled in spring 2016.

Draw downs will limit boat movement and recreation. Among the impacts, Colonial Creek Boat Ramp, Colonial Creek canoe launch, boat-in camping at Buster Brown and Thunder Point, the National Park Service dock and the ferry dock will be unusable during some or all of the construction.

Last year, City Light improved the road from the landing and docks to enhance safety.

The access road for the docks in 2013.

The access road after safety improvements.