sentences:  The headwaters of the Arthur River is located about north of Wagin in the Arthur River Nature Reserve near the small settlement of Arthur River on Albany Highway.The longest tributary of Arthur River is Beaufort River but other tributaries include Hillman River, Kojonup Brook, Narrogin Brook and Yilliminning River.The river flows in a generally south-westerly direction until it meets with the Balgarup River to form the Blackwood River.