The Kaukonahua Stream or Kaukonahua River is a river on the island of Oahu which is one of the Hawaiian Islands. Including its longer South Fork, the stream's total length is . It flows down in a generally northwest direction, from into the Pacific Ocean. The North and South forks meet at coordinates . It is the longest river of the whole island group. It empties into Kaiaka Bay near Waialua, Hawaii on the North shore.
Water quality monitoring has identified elevated levels of pollutants in Kaiûaka Bay and nearby waterways that drain the Kaukonahua River watershed. Some contaminants have been reported to exceed Hawaii State Water Quality Standards.