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Wastewater Treatment Plant
Wastewater Treatment Plant

The Wastewater Department provides the following services:

  • Treatment process
  • Solids removal
  • Disinfection
  • Clarification
  • Storm Drainage
  • Collections System
  • Operation, maintenance, and repairs to all systems
  • Industrial monitoring/metering
  • Expansion of existing sewage system

Overview of the System

The City of Prosser Wastewater facilities consist of a sewage collection system and a wastewater treatment facility. The sewage collection system includes approximately 129,175 linear feet (LF) of gravity pipe (with a majority of the pipe being 8-inch diameter), 11,874 LF of force main, and 6 sewage lift stations.


Since 1948, the City of Prosser has provided treatment and disposal for residential, commercial, and industrial wastewater generated within the City. Prosser's wastewater treatment facilities have undergone many expansions and upgrades since original construction, the most recent upgrade being in 2016.  These modifications have been in response to increasing population, increasing industrial waste treatment needs, and increasingly stringent discharge requirements.


Prosser's wastewater treatment facilities are located on the north bank of the Yakima River, below Prosser Dam, and immediately adjacent to the Chandler Canal.