Sewerage for the City of Yakima was first provided in 1886. By 1891 most of the original central business district was set up for the area’s raw waste to be conveyed to the Yakima River. In 1936, the  primary treatment plant was constructed, providing treatment for 2.0 Million Gallons per Day (MGD).  Nearly all of the City’s approximately 27,000 residents were connected to this system.

In 1955 food processing wastewater(fruit and vegetable waste) was separated from domestic wastewater treatment and sent to a 100-acre spray field which still borders the plant on the south and east. Although the spray field eliminated a major source of organic loading to the plant, deteriorating river water quality led the Washington State Pollution Control Commission to direct the city to provide secondary treatment. In 1965, the city added secondary treatment by building two 170-foot diameter trickling filters. The new secondary treatment facility was capable of treating a flow of 15.4 MGD.  In 1972, amendments to the Federal Water Pollution Control Act required the City to re-evaluate the performance of its wastewater treatment facility. This eventually led to further facility upgrades including the addition of an activated sludge system.

In 2009, the facility improved systems further by removing gas chlorination disinfection and installing an ultra violet disinfection system.   More recent upgrades, as described above, are helping to recover and sustainably re-use resources, expand capacity, encourage business and industry, improve the environment, reduce electricity costs and keep ratepayer costs down.