Since construction of the Breakout Creek outlet in 1937 to drain the Reedbeds (see above), and the closure of the former Port Adelaide Wastewater Treatment Plant with the diversion of wastewater to Bolivar Waste Water Treatment Plant in 2005, the upper reaches of the Port River now receive only limited amounts of locally derived stormwater, and are now largely marine. Flushing of West Lakes occurs through a one-way system that draws in seawater from the Gulf through an inlet off the coast at the southern end. The Lakes discharge into the upper reaches of the Port River at Ethelton.