Unified Sewer Plan Update

Unified-Sewer-Plan-iconEnvisioning Our Future Sewer System

Wastewater treatment facilities around Puget Sound face regulatory and environmental pressures to develop, implement, and improve wastewater treatment processes to meet increasing water quality regulations for effluent discharge. 
The Unified Sewer Plan will reflect Pierce County’s ongoing commitment to a healthy Puget Sound and our goals for supporting vibrant communities, effective government, and economic growth.
About the USP
What is the Unified Sewer Plan?

Pierce County Planning and Public Works is currently updating the Unified Sewer Plan, which is a comprehensive plan that will guide the Pierce County Sewer Division for the next 20 years. The plan describes the sewer service area, existing collection and treatment system and outlines policies, goals and approached that will guide future expansion and improvements. 

The Unified Sewer Plan will also address elements required by the Department of Ecology, including the general sewerage planning, expansion of sustainability, resource recovery efforts (biosolids and biogas management), and improved treatment to reduce nutrients in outflow.Unified Sewer Plan Graphic Opens in new window
  1. Stakeholders
  2. Goals
  3. Policy Topics

Sewer Division staff will engage with ratepayers, elected officials, tribal partners, stakeholders, and regulators to understand their expectations and to develop strategies for how best to balance those expectations while maintaining affordable rates. 

Our business case evaluations will include consideration of the environment and social awareness to the standard cost/benefit/risk analysis, and address sustainability, sewer capacity, resource recovery and wastewater treatment byproducts (such as biosolids, biogas and nutrient reduction).


Pierce County launched the Unified Sewer Plan update project in March of 2020 and expects to finalize the plan in 2025. Stakeholder engagement will assist in initial plan development, analysis and environmental review of alternatives.  
Washington State Department of Ecology and the Pierce County Council have approval oversight of the final plan. See below for more detail about the timing and goals for each phase.  

(Note: Timelines have shifted due to the pandemic response needs, prioritized policy work, and to ensure coordination with broader Pierce County’s Comprehensive Plan timing.)
  1. Prework/Contracting
  2. Phase 1
  3. Phase 2
  4. Phase 3
  5. Adoption

The prework and contracting took place in 2019-2020.