- ABC Recycling
- ACF West
- Advanced Drainage Systems
- AEC
- Alliance Technical Group
- ALL4 Inc
- Amiad USA
- Anchor QEA
- Antea Group
- Apex Companies
- Apex Laboratories
- AQUALIS
- Asotin County
- Associated Earth Sciences, Inc.
- Badger Daylighting
- Basalite Concrete Products
- Bedrock Natural Stone
- Bellevue Utilities
- Beveridge & Diamond PC
- Blaine Tech Services
- Blue Environmental
- Brown and Caldwell
- Bureau Veritas
- CatchAll Environmental
- Cedar Grove Composting
- City of Arlington
- City of Auburn
- City of Bainbridge Island
- City of Battle Ground
- City of Bellevue
- City of Bremerton
- City of Camas
- City of Covington
- City of Des Moines
- City of Edmonds
- City of Edgewood
- City of Everett
- City of Federal Way
- City of Kirkland
- City Lake Lake Stevens
- City of Mukilteo
- City of Newcastle
- City of Olympia
- City of Port Orchard
- City of Puyallup
- City of Redmond
- City of Richland
- City of Ridgefield
- City of Sammamish
- City of Seattle
- City of Spokane
- City of Sumner
- City of Tacoma
- City of Tumwater
- City of Washougal
- Clean Earth
- Clean Harbors Environmental Services
- CleanWay Environmental Partners Inc
- Clear Creek Systems
- Clear Water Services
- Community Transit
- Concrete Canvas US, Inc.
- Contech Engineered Solutions LLC
- David Evans and Associates, Inc.
- EA Engineering, Science, and Technology, Inc., PBC
- ECS Pacific, Inc.
- Encore Environmental, LLC
- Enpurion
- EnviroMet
- ERSM
- Eurofins Environment Testing Northwest
- Evergreen State College
- Evergreen StormH2O
- Farallon Consulting
- Floyd Snider
- FIeldLab
- Flexamat
- Forerunner
- GeoEngineers
- Georgia Pacific Gypsum LLC
- Geosyntec Consultants
- GSI Water Solutions, Inc.
- Gullywasher
- Haley & Aldrich, Inc.
- Hazen & Sawyer
- HDR
- Herrera Environmental Consultants
- HNTB
- Holt Services, Inc
- Husky Terminal
- Integrity Environmental
- Ironclad Environmental Solutions
- Janicki Industries
- Jensen Infrastructure
- K&L Gates
- Kindred Hydro
- King County
- King County International Airport
- Kitsap County
- KPFF
- Landau Associates
- Langan
- Louis Dreyfus Company
- Marten Law
- Maul Foster & Alongi
- Mead and Hunt
- Newterra
- Northern Environmental
- OptiRTC
- Oregon State University
- Osborn Consulting
- Otak
- Pacific Coast Carbon
- Pacific Seafood
- Pacific Stormwater
- Pape
- Parametrix
- Parks Tacoma
- PDC Tank Rentals
- Pierce County
- Pollution Prevention Resource Center
- Port of Bremerton
- Port of Everett
- Port of Grays Harbor
- Port of Ilwaco
- Port of Olympia
- Port of Seattle
- Port of Skagit County
- Port of Tacoma
- Port of Vancouver USA
- Prinsco
- Rain for Rent
- Ramboll
- Recology
- RIE Consultants, LLC
- Riparia Environmental
- Rivers Edge Environmental Services, Inc.
- RK Industries, LLC
- SCS Engineers
- Seaport Sound Terminal, LLC
- Seattle Public Utilities
- Simpson Door Company
- Skagit County
- Snohomish County
- Sound Environmental Concepts LLC
- Sound Transit
- Specialty Analytical
- SSA Marine
- Stoel Rives LLP
- Stormshield BMPS Inc.
- StormTank
- StormTrap
- Stormwater Controls
- StormwaterBiochar
- Tacoma Public Utilities
- Terraphase Engineering Inc.
- The Boeing Company
- The Integrated Group
- Thurston County
- TRC
- Trident Seafoods
- Triverus
- United Rentals Fluid Solutions
- University of Washington
- Washington State Department of Ecology
- Washington Stormwater Center
- Waste Connections
- WaterTectonics
- Weber Thompson
- Whirlwind Clean & Green
- Whitney Equipment Co.
- WM
- WSP USA
- Zurn