Optimizing rapid rate filter performance for turbidity (particle) removal provides better public health protection for consumers.
Each month, rapid rate treatment plants across the state submit operation reports to document regulatory compliance. We enter maximum daily turbidity values from the 55 active treatment plants into Optimization Assessment Software and rank systems according to their relative performance.
Washington State Rapid Rate Treatment Plant Performance Trends (PDF) shows turbidity reduction performance improvement by all rapid rate treatment plants in Washington as a group from 2001 through 2024. Improved performance means improved public health protection. Read more about optimization criteria (PDF).
By optimizing water quality produced by their existing facilities, these utilities are able to cost-effectively provide a larger margin of safety and build greater resiliency to handle natural disasters and other unforeseen events.
Congratulations 2025 TOP Performers!
Turbidity monitoring data for 2025 show that Washington's conventional and direct filtration surface water treatment plants continue to perform above national regulatory standards—and provide better public health protection.
We are very pleased to introduce our new Quarter Century Award! Three systems are continuing their run of excellence and have reached a significant milestone of 25 consecutive years of optimization! This is a tremendous feat to celebrate!
We also award bronze, silver, gold, and platinum certificates to systems the first time they meet the turbidity goals for 3, 5, 10, and 15 consecutive years, respectively, as well as our 20-year award. This year we issued ten consecutive year awards, and fourteen other systems have been continuously optimized for 3-17 years.
See a complete list of systems that met optimization goals in 2025.
Congratulations to the treatment plant operators, utility managers, and decision makers for making this happen!
Quarter Century Award
- Arlington Water Department (2001-2025)*
- Lake Whatcom Water and Sewer District—South Shore Water System (2001-2025)*
- Pasco Water Department (2001-2025)*
Twenty-Year Award
- City of Kelso (2006-2024)*
Platinum Award Recipients (15 or more years)
- River Bend Water System (2009-2025)
- City of Yakima (2010-2025)
- City of Bellingham (2011-2025)*
Gold Award Recipients (10 to 14 years of continuously optimized performance)
- Castle Rock Municipal Water (2012-2025)
- Town of Metaline Falls (2012-2025)
- Department of Energy/200 W (2015-2025)
- Hoquiam Water Department (2015-2025)
Silver Award Recipients (Five to nine years of continuously optimized performance)
- Friday Harbor (2017-2025)
- City of Port Angeles (2019-2025)
- Seattle Public Utilities (2019-2025)
- City of Leavenworth (2020-2025)
- Roche Harbor Water System (2020-2025)
- City of Everett Public Works Department (2012-2025)*
- City of Ilwaco Water Department (2021-2025)*
Bronze Award Recipients (Three or four years of continuously optimized performance)
- Carbonado Water Department (2022-2025)
- Island View LUD 9 (2022-2025)
- City of Chelan Water Department (2023-2025)*
- Ryderwood Improvement and Service (2023-2025)*
*First-time award recipient for 2025.
Get the information and assistance you need to improve treatment plant performance. Contact our office at 360-236-3100 and ask for a surface water treatment specialist. Or go to our Contacts and Office Location page where you'll find program email addresses, and an interactive map with county assignments. Our Staff Directory page lists staff by program.