Surface elevation : 1,604 ft (489 m)
Ross Lake is a large reservoir in the North Cascade mountains of northern Washington state, USA, and southwestern British Columbia, Canada. The lake runs approximately north-south, is 23 miles (37 km) long, up to 1.5 miles (2.5 km) wide.
The U.S. portion of Ross Lake is in the Ross Lake National Recreation Area. North Cascades National Park is adjacent to the west and south, while the Pasayten Wilderness is east of the lake. In British Columbia the lake is a part of Skagit Valley Provincial Park, and Manning Provincial Park is nearby to the east.
Ross Lake is formed by the impoundment of the Skagit River by Ross Dam, which is operated by Seattle City Light for hydroelectric power generation serving Seattle, Washington, and surrounding areas. After leaving Ross Lake, the Skagit River flows through two more reservoirs before running to Puget Sound.