Ross Lake Dam Trail at North Cascades NP

Ross Lake is a large reservoir in the North Cascade mountains of northern Washington state, United States, 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, and the full reservoir elevation is 1,604 feet above sea level (489 m).

Ross Dam is a 540-foot (160 m)-high, 1,300-foot (400 m)-long concrete thin arch dam across the Skagit River, forming Ross Lake. The dam is in Washington state, while Ross Lake extends 23 miles (37 km) north to British Columbia, Canada. Both dam and reservoir are located in Ross Lake National Recreation Area, is bordered on both sides by Stephen Mather Wilderness and combined with Lake Chelan National Recreation Area they make up North Cascades National Park Complex.