Water System Regulatory Compliance Plans
Project Status
To help keep area residents informed of our construction progress, we will post project updates to this site on a regular basis. Click here to see status updates.
Background
Washington State requires the City to update its Comprehensive Water System Plan every 10 years under state health regulations (WAC-246-490). The current plan expires in June 2026, and the updated plan must be submitted to the Washington State Department of Health for review and approval.
In addition, federal law (the America’s Water Infrastructure Act of 2018) requires communities to review and update their Risk and Resilience Assessment (RRA) and Emergency Response Plan (ERP) every five years. The City last completed and submitted these updates in 2021.
The updated Emergency Response Plan will be incorporated into the updated Water System Plan to ensure a coordinated approach to system safety, reliability, and emergency preparedness.
Description
The City is updating several key plans that guide how our water system is managed, maintained, and protected. This project includes updates to the Comprehensive Water System Plan, the Risk & Resilience Assessment (RRA), and the Emergency Response Plan (ERP). These plans are required on regular cycles to ensure the water system continues to meet state and federal standards and reflects current conditions.
The Comprehensive Water System Plan provides a detailed review of the City’s water system, including infrastructure, operations, maintenance, water demand, policies, and system improvements. This update is required in 2026.
The RRA and ERP evaluate potential risks to the water system – such as natural disasters and intentional threats – and outline how the City would respond to and recover from emergency events. These updates are also required in 2026.
Work on these plans will be coordinated with other major Public Works and Citywide planning efforts to ensure consistency across related projects and initiatives.
Project Timeline
Planning/Design: Q1 of 2025 – Q2 of 2027
Estimated Budget
$458,300
Contact:
Lauren Kumle, Utility Engineer; (206) 549-1036; lauren.kumle@mercerisland.gov
Status Updates
July 1, 2026
Development of the Comprehensive Water System Plan is continuing; however, adoption of the plan has been delayed to align with the City's Comprehensive Plan update. Coordinating these efforts ensures the Water System Plan incorporates the City's adopted growth forecasts, land use assumptions, and planned development, providing an accurate foundation for future water system planning and capital improvements. HDR Engineering continues to advance technical analyses and other plan elements while the Comprehensive Plan update is finalized.
April 1, 2024
City growth data for the next 10 years and 20 years has been provided to HDR and they have begun analyzing the results and evaluating impacts growth will have on the water system. This data will allow the City to properly plan for infrastructure improvements over the next 20 years.
January 1, 2026
HDR has started to update the City’s Risk and Resilience Assessment (RRA) to comply with America’s Water Infrastructure Act (AWIA) section 2013/Safe Drinking Water Act (SDWA) section 1433. This update will be completed over the next 6 months and will involve coordination of City staff from several different departments and HDR engineers. Following the completion of the RRA, the update to the Emergency Response Plan (ERP) will begin.
May 2, 2025
The contract with HDR Engineering has been executed, and they will serve as the consultant for this project. City staff met with HDR staff to establish key project elements and schedule. HDR has begun reviewing background documents and integrating GIS data to update their comprehensive hydraulic model of the water system. The next major step is City staff to provide any missing data to HDR.