The City of Snoqualmie is projected to increase in population to over 18,000 people in the next 20 years, necessitating a major upgrade to the treatment plant and river bank outfall.

Waste Water


The city had an engineering report and design documents prepared for these improvements on a fast track time schedule. The engineering report for the project evaluated alternate processes for nutrient removal , eventually selecting a low speed "Carousel" oxidation ditch configuration for anaerobic / anoxic / aerobic treatment. The city began planning work in early 1994 and design work in early 1995. Construction was completed on the wastewater pumping, transfer, and treatment facilities in 1997. The plant was then upgraded again in 2003 increasing the capacity.

New Treatment Plant

The new 3.0 mgd treatment plant includes mechanically cleaned bar screens, vortex grit removal, secondary treatment by a modified Bardenpho process for advanced nutrient removal, traveling hood effluent sand filtration, and ultraviolet disinfection. Sludge disposal is by wastage to existing facultative stabilization ponds. Effluent disposal is based on discharging secondary effluent to a new Snoqualmie River outfall in the winter, and Eagle Lake for golf course irrigation in the summer. All water sent to Eagle Lake meets Class A Reclaim Water Standards.

Fallsgro Biosolids

Available to Residents (free)

The City of Snoqualmie’s Water Reclamation Facility, with the addition of Fallsgro biosolids production, is now capable of recapturing wasted nutrients and transforming them into a slow release nutrient-rich organic soil enhancer. The city has received clearance by the State of Washington Department of Ecology to make its Class “EQ” (Exceptional Quality) biosolids product available to the public. The product can be used in gardens and areas that require fertilizer. Biosolids Fact Sheet (PDF)

If You Have a Septic System

Routine maintenance of your septic system may cost a few hundred dollars, whereas a failed septic system can cost up to $15,000 to replace, and poses risks to you and your neighbors.

All septic systems have a limited life expectancy so one can expect that they will fail at some point in time. Failing septic systems can expose you, your family and your neighbors to sewage, containing pathogens that can cause disease. Sewage can also contaminate ground and surface water, polluting wells, rivers and creeks near your home.

You may know your septic system is failing if there are:

  • Bad odors around the drainfield, especially after heavy rains or heavy water use
  • Very wet spots with lush green grass growth over the drainfield or septic tank areas
  • Gurgling sounds in the plumbing system
  • Plumbing or septic tank back-ups
  • Slow draining fixtures
  • Standing water in the drainfield

King County Board of Health Code

The King County Board of Health code requires all septic owners to maintain their systems to protect and preserve public health. Septic systems require maintenance every 3 to 6 months with Mound and Sand Filter systems, every 6 to 12 months for some Pressure Distribution systems, or every 1 to 3 years for Gravity systems. The presence of Aerobic Treatment Units (ATUs) and household garbage disposals can affect inspection frequency.

Inspect & Monitor Your System

Contact a certified On-site System Maintainer to inspect and monitor your system on a regular basis to extend its useful life. A certified OSM has two or more years of experience, has completed a monitoring and maintenance class and has passed an exam given by Public Health - Seattle and King County.


Your septic system is considered "non-functioning" if sewage is surfacing on the ground and routine maintenance cannot fix it. If this is the case, you should contact the Public Works Department immediately to determine your best course of action.

More Information

For more information on septic systems, proper maintenance, and how to find a certified OSM, please visit Public Health - Seattle and King County. Please note this is an external website, and not all information may apply to residents within the Snoqualmie city limits.

Reclaimed Water

Reclaimed water is wastewater that gets treated to such a high level that it can be used safely and effectively for non-drinking water uses such as landscape and agricultural irrigation, heating and cooling, and industrial processing. Reclaimed water is available year-round, even during dry summer months or when drought conditions can strain other water resources.