The Marshall Onsite Wastewater Disposal Zone
The Marshall Onsite Wastewater Disposal Zone is a joint venture between property owners and the County of Marin. The Zone was formed in 2007 in response to concerns about human pathogens contaminating shellfish beds in Tomales Bay. The Zone boundary includes 53 parcels, 48 of which are connected to the system.
Each connected property has an upgraded septic tank and effluent pump that lifts wastewater to a pressurized main delivering waste to the six-acre treatment site. Here, wastewater is circulated through an underground pretreatment unit and discharged to the community-scale leachfield.
Construction of the project was funded by property owners, Marin County, the San Francisco Regional Water Quality Control Board, and the U.S. Environmental Project Agency. While some property owners paid for their assessment in a lump sum, most pay annual assessments with their property taxes. Property owners also pay an annual fee for the ongoing operation and maintenance of the system.
Marin County Environmental Health Services (EHS) is responsible for the administration of the Zone and contracts with a qualified wastewater management company to manage the system. The current operation and maintenance contractor is Natural Systems Utilities- CA (NSU).
If you have questions or need further information, please contact the EHS office at (415) 473-6907 Monday through Friday from 8:00 AM to 4:00 PM.
For immediate response to a problem in the Zone, call the NSU 24-hour number: 707-254-1931. Since this number may also be called for non-emergency questions, specify if the call is urgent or not.