Barnston MountMount Barnston is a mountain located at Coaticook, in the regional [county municipality] of Coaticook, in the administrative region of Estrie, in Quebec, just north of the American border with Vermont. Its altitude is 743 metersGeographyThe mountain is located near Lyster [Lake (Estrie, Canada)|Lyster Lake] and the hamlet of Baldwin Mills in the agricultural valley of the Coaticook River.