Commencing from the mouth of Sungai Bako at position 01° 41' 12"N, Longitude 110° 25' 26"E, then following a line across to position Latitude 01° 41' 00"N, Longitude 110° 25' 26"E proceeding upstream to Sungai Deda, Loba Dedap, Sungai Serai and Sungai Pingam then to Sungai Santubong.