Park by the Heli Sika base at the gates to Poronui Station, the track is well marked with orange triangles on the gravel-road verge.
A rather un-inspiring hour or two walking along dusty gravel roads before getting into some small patches of eucalyptus and finally native before hitting the river.
Take care to find orange marker over the river when you cross - can lose your bearings on the river flats. Oamaru hut has a lovely outlook over the river valley - very popular with hunters and the odd adventurous fisherman.