The City and County of Honolulu is responsible for the collection and treatment of wastewater for the majority of the Island of Oahu. Other wastewater is dealt with by several private systems and by the military. The City’s system is divided into eight major drainage basins defined by the Wastewater Treatment Facilities to which they drain. These are shown on Figure 1. The largest are the Ala Moana and Hart Street basins which serve the City of Honolulu, and drain to the Sand Island WWTP.