Revised Larkfield Estates Sewer Connection and Financing Program

    Key Updates

    • (4/3/18) Temporary Holding Tank Information from Permit Sonoma - Permit Sonoma has released information describing how temporary holding tanks may be used by homes that plan to connect to sewer service after sewer service becomes available.  The use of temporary holding tanks will allow property owners to build in the footprint of their existing septic system and inhabit their home even if sewer service is not yet available.  For more information please visit the Permit Sonoma website at
    • (3/22/18) Point of Sale Requirement Removed - Based on recent feedback, the Water Agency has removed the point of sale requirement under this revised proposal. The revised proposal, outlined below, does not require connection to the sanitation system at the time of sale or transfer of property ownership.  There is no requirement to connect to the sanitation system under this proposed program.
    • (3/22/18) Assumable Loans – Based on recent feedback, the Water Agency is working to make all loans associated with this program assumable and transferrable to new property owners.


    The Airport/Larkfield/Wikiup Sanitation Zone (ALWSZ) is owned and operated by the Sonoma County Water Agency (Water Agency) to collect and treat wastewater.  The Water Agency is proposing to (1) make sewer service voluntarily available to current property owners within the ALWSZ boundary that were impacted by the Tubbs Fire, and (2) provide low cost financing for property owners wishing to connect. It is anticipated that sewer service will be available in 2020. 

    Permit Sonoma has indicated on their website that 'properties with compliant septic systems will not compelled to connect' to the new sewer system. For more information please visit the Permit Sonoma website at

    Sewer Service Costs and Financing

    Annual Service Charges

    The current Annual Service Charge for the ALWSZ is currently $901/year for a single family dwelling unit.  This charge must be paid annually by property owners receiving sewer service.  The fee typically increases between 4% and 5% per year.

    Airport/Larkfield/Wikiup Sanitation Zone Connection Fees

    Connection fees ($12,023) owed to the ALWSZ are due at the time of occupancy.  The ALWSZ is proposing to provide 20 year, 2% interest assumable loans for property owners impacted by the fire. Loan payments would be about $750/year from year 2020 to 2040.

    Sewer Collection System Construction Costs                                                                    

    It is estimated that the public sewer system will cost about $45,000 to construct per parcel, including laterals up to each property line.  This estimate is conservative meaning that the actual costs may be lower.  The following financing is proposed for current property owners:

    • No interest accrued or payments required until 2030.
    • Property owners would be provided with a 20-year, 2.5% interest assumable loan starting in year 2030. Loan payments would be about $2,750/year from year 2030 to 2050.

    The Connection Fee and Sewer System Construction financing options are proposed to be available to property owners that connect to the system before construction of the sewer collection system is compete. Loan balances and payment schedule could be transferred to future property owners.

    There is no requirement to connect to the sewer upon transfer or sale of the property.  Current and future property owners could voluntarily connect and pay the connection fee and sewer construction costs.


    Next Steps

    The Water Agency will seek direction from its Board of Directors to construct the sewer and offer the financing program in May 22, 2018.

    To ensure that you will be successfully contacted as information becomes available, please provide Water Agency Program Specialist Sophie Porcelli (contact information below) with your contact information and property address.

    Questions or comments? Contact Sophie Porcelli at or (707) 524-6430.


    Parcels Eligible to Connect to Sewer Under the Proposed Plan