Officials are still trying to decide how to deal with a March 15 debris avalanche that has blocked a local access road that connects two reservoirs within North Cascades National Park.
Park officials said an estimated 56,000 cubic meters of debris came down in the avalanche measuring almost 200 feet across at the toe of the avalanche.
The slide has cut the Ross Dam haul road, which is about a mile long and is an key administrative road.
While the road does not connect to any public road, it serves several organizations.
It provides Seattle City Light, operator of three hydroelectric dams within the park, with access from Diablo Lake to the Ross Powerhouse and the top of Ross Dam; Ross Lake Resort, a park concession operator of floating cabins on Ross Lake, with transportation service for their guests to and from Diablo Lake; and paddlers with portage between Diablo Lake and Ross Lake.
The debris avalanche covers the road and destroyed Seattle City Light’s barge dock, Ross Lake Resort’s truck, and the National Park Service’s canoe and kayak landing.
Implications for Seattle City Light operations are significant, as access to the Ross Powerhouse and the top of Ross Dam is limited to foot traffic, prohibiting the use of any heavy equipment that may be necessary for service or repair, said a park news release.
The area remains unstable and dangerous. A contractor has been hired to evaluate and stabilize the cliff above the slide. Several large rocks could still fall and double the volume of material, making recovery even more difficult and time-consuming.
After the area is evaluated and stabilized, it could take several months to reestablish the road. The size of the slide makes it unfeasible to remove, so Seattle City Light plans to develop a new barge landing upstream of the slide to provide access to Ross Powerhouse. A new dock and trail downstream of the slide are also planned to provide Seattle City Light with access to the top of Ross Dam, support Ross Lake Resort and National Park Service operations, and reestablish portage between Diablo Lake and Ross Lake for paddlers.