Ross Lake, the largest of the three reservoirs, winds nearly 25 miles from Ross Dam to Hozomeen on the Canadian border. The only vehicle access is via Hope, British Columbia, but small motor boats and canoes/kayaks can be portaged around Ross Dam from Diablo Lake. Nineteen boat-in campgrounds and Ross Lake Resort are available for those looking to spend multiple days in this remote landscape.
Ross Lake is currently being threatened by pollution from inefficient 2-stroke motor boats using the lake. The park is currently working on a General Management Plan for Ross Lake. NPCA has been involved in the development of this plan and has promoted a regulation requiring only more efficient, less polluting 4-stroke engines be allowed on the lake. Noise from float planes landing on the lake is also a nuisance and source of pollution, that should be better regulated. Finally, park service resources are being stretched thin by its requirement to control border crossing on the northern terminus of Ross Lake.