The St Regis River begins at Lookout Pass in which mountain pass on the Idaho/Montana border? 
St. Regis River (Montana): The St. Regis River is an approximately 32.5 mi tributary of the Clark Fork of the Columbia River in Montana in the United States. St. Regis River (Montana):  It begins at Lookout Pass on the Idaho/Montana border, flows east and ends at the confluence with the Clark Fork in the city of St. Regis.
i don't know