Airport-Larkfield-Wikiup Sanitation Zone Consolidation

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Wastewater service for Airport-Larkfield-Wikiup Sanitation Zone (ALWSZ) is currently provided by Sonoma Water. A project is now taking shape through which some or all of the ALWSZ will consolidate with Windsor Water District. Once the project is complete, wastewater service will instead be provided by the Windsor Water District through its Water Reclamation Facility (WRF).


ALWSZConsolidationTOW ALWSZ service area


Why is the transition of wastewater services to Windsor Water District taking place?

The ALWSZ treatment plant is approaching the end of its operational lifetime and needs major renovations requiring significant financial investment. Sonoma Water conducted evaluations of alternative solutions and determined the best option is to consolidate ALWSZ’s operations with the Windsor Water District. By decommissioning the ALSWZ treatment plant and redirecting its wastewater to Windsor’s WRF via a new pipeline, Sonoma Water and its customers will avoid large cost increases that would be necessary to pay for substantial upgrades to the treatment plant. Windsor will benefit by using existing water storage at the ALSWZ treatment facility, enabling 100% of the wastewater from both systems to be recycled during most years, leading to increased beneficial reuse of recycled water and conservation of drinking water supplies. This is one of several efforts Windsor is developing to help attain net-zero status at its WRF. This path forward is the most cost-effective alternative and the most feasible to achieve, and will ensure continued reliable operations and full regulatory compliance.

When is the transition expected to be implemented?

 This is a complex transition/consolidation, and implementation will take some time. Together, Sonoma Water and Windsor Water District are carefully proceeding through a multi-step process, starting with developing a contract for the WRF to treat ALSWZ wastewater. That step will be followed by construction of a permanent sewer connection between ALSWZ and WRF, anticipated to be built in 2024. Once that connection is in place, sewer services will transfer from ALWSZ to the Windsor Water District.

Finally, some or all of the ALWSZ service area may officially become part of the Windsor Water District, and those customers will become Windsor Water District customers (ALWSZ areas not included in the legal consolidation, if any, will nonetheless be serviced by the Windsor Water District under contract with Sonoma Water).

The timing of the consolidation is uncertain and won’t be known until the process has moved further along.

How will this affect ALWSZ customers?

An important part of the consolidation planning and discussions centers on how to make this transition smooth for ALWSZ customers — there will be no interruption in service and our goal is that customers will notice little, if any, difference during or after the transition. The overall charges for sewer services between the two agencies are similar, and ALWSZ customers’ sewer services will continue to be charged on their property tax bill until the very final step of the consolidation. At that point, those customers who become Windsor Water District customers will be billed monthly based on their water consumption. 

Sonoma Water customers may begin seeing Windsor service vehicles in their area as soon as July of 2024; however, those customers should continue to contact Sonoma Water with any service issues, until otherwise notified. 

Your patience and understanding are appreciated as Sonoma Water and Windsor Water District work to maximize regional resources, increase the availability of recycled water, and help foster sewer rate stabilization.

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For more information: Contact Shannon Cotulla, Public Works Director/Engineer, Town of Windsor, (707) 838-1006.