The Marshall Onsite Wastewater Disposal Zone

Community Development Agency

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 a.m to 4:00 p.m.

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.


District Map

Marshall Wastewater District Service Area

Responsibilities of Property Owners and Residents

The proper use and maintenance of the wastewater system is vital to the proper functioning of the community system and potentially saves money on individual and community repairs. Each property owner is responsible for maintaining their household plumbing and the wastewater line running to their septic tank. The District’s operation and maintenance contractor inspects each septic tank annually and EHS notifies property owners when it is time to have a tank pumped. The property owner is responsible for scheduling and paying for this pumping in a timely manner.

Residents should familiarize themselves with the proper procedures to following in an emergency. If your STEP pump alarm goes off, immediately call NSU’s 24-hour number: 707-254-1931 and provide your name, property address, how long the alarm has been sounding, and any other observations that may be helpful to the maintenance person. Please print each of these documents for handy reference.

RENTAL PROPERTIES: All tenants should receive clear instructions on what to do when the power is out or the system’s alarm goes off. Please provide the following information to tenant.

Sewer System Management Plan

The following Sewer System Management Plan (SSMP) has been prepared pursuant to State Water Resources Control Board Order No. 2006-0003-DWQ, Statewide General Waste Discharge Requirements for Sanitary Sewer Systems, and Order No. WQ-2013-0058-EXEC, Amending Monitoring and Reporting Program for Statewide General Waste Discharge Requirements for Sanitary Sewer Systems.

Related Marin County Ordinances

Correspondence and Announcements