Commencing from Tanjung Muara Tebas at position Latitude 01° 39.05' N Longitude 110 29.50' E; then following a line across to Tanjung Embang at position Latitude 01° 37.82' N Longitude 110° 30.50' E; and proceeding upstream across to Loba Batu Blat at Tanjung Sedap at position Latitude 01° 34.76' N Longitude 110° 20.13' E; then following a line across to Tanjung Buaya at position Latitude 01° 34.63' N Longitude 110° 25.90' E; and proceeding upstream towards its source.