Dillon Beach Feasibility Study

Community Development Agency

Protecting Public Health and the Environment

The Marin County Environmental Health Services (EHS) endeavor to protect environmental health, public health and the well-being of all residents, workers, and visitors by preventing injury and the spread of disease. We are involved in the Dillon Beach Feasibility Study Project because we work to promote sound environmental health practices through education and the enforcement of public health statutes and regulations.

This is an update on the Dillon Beach Village Feasibility Project. To recap, we held a series of meetings in 2018 and 2019. During that time, residents and property owners answered a survey about their key issues and concerns related to water and wastewater. At the final meeting, there was unanimous support to proceed with a grant request to conduct a feasibility study of alternatives for a community wastewater (w/w) system. This is a no commitment step to gather information so that the community can make an informed decision on how to best address concerns with on-septic systems.

Dillon Beach Feasibility Study

Contact Us

Marin County Civic Center
3501 Civic Center Drive
Suite 236
San Rafael, CA 94903
(415) 473-7146 - T
(415) 473-4120 - F



The Feasibility Study Tasks

In the first phase of the project, we identified the status of available resources, existing problems, and created a narrative on water resources needs and assets for the community. In the second phase of the project, we are conducting a feasibility study of alternatives for a community wastewater system.

A feasibility study could include the following tasks:

  1. Background and study area characteristics – this first task will cover the compilation, review, and organization of all relevant background information on the project area conditions, prior studies, and regulatory requirements related to use of Onsite Wastewater Treatment Systems (OWTS)
  2. Problem Assessment – the purpose of this task is to provide an assessment of the nature and extent of operational and environmental problems associated with the current onsite wastewater systems in Dillon Beach Village. The objectives in this step are (i) evaluating the functioning problems, conditions, and constraints for continued use and/or upgrade of existing septic issues; and (ii) analyzing the impacts on groundwater, including problems associated with overt surface failures as well as cumulative watershed effects due to the large number and high concentration of wastewater discharges
  3. Based on the results of task (1) and task (2), the potential service area boundaries for a community wastewater project will be developed in collaboration with the community, the county, and Regional Water Board staff members.
  4. Formulate wastewater alternatives – a preliminary list of options, applicable regulatory requirements, and other alternatives will be compiled and will be reviewed with the community before finalizing the list of options to be examined. A broad range of conventional and alternative wastewater technologies will be considered, as applicable, within each alternative. For example. Innovation onsite technologies, annexation to the existing facilities, cluster and community wastewater treatment etc.
  5. Development and Analysis of Alternatives – under this task an analysis and comparative review of the various alternatives will be completed for the purpose of identifying the apparent best wastewater management plan for the community.
  6. Public outreach – the task covers the public involvement and education activities for the project, including community meetings, and process-related information .
  7. Project report – the last task incorporates the preparation of the previous projects report.


Project Area – The Village

There are four subareas within Dillon Beach: Oceana Marin, Village, Dillon Beach Resort, and Lawson’s Landing. This project focuses on the historic Village, which is the older and tightly clustered area of the community. Development began here in the 1910s, with most houses built in the 1930s and 1940s on very small lots, typically 1,725 square feet. Streets in this area are narrow and aligned in a general grid pattern. Of the 160 lots in the Village, 149 are developed. The Village has transitioned over the last decades from seasonal to year-round uses. Most of the area is zoned C-R1-BD for coastal single-family residential.

Water Supply


Water service to the Village is supplied by Coast Springs Water Company (owned and operated by California Water Service), which is an investor-owned utility (public water system) regulated by the California State Public Utility Commission (PUC). Coast Springs obtains its water from the following sources:

  1. Lower Well, also referred to as Well #4: This shallow well is their largest source of water and is in the channel alluvium of Dillon Creek Gulch, immediately south of the Village. This well yields between an average of 18,000 to 25,000 gallons per day, fluctuating according to the creek flow.
  2. Hilltop Wells: They maintain six vertical drill wells that service Coast Springs customers in Oceana Marin and the Village.
  3. Seasonally, they purchase water from a private well that is nearby Lower Well in the Dillon Creek Gulch.

The Village makes up approximately 60% of the Coast Springs system. Cal Water also provides service to 82 nearby properties in Oceana Marin and 13 residences south of the Village between Cliff Street and Bay Drive.

Water Storage

There are two storage tanks: One 120,000-gallon tank at their water treatment plant above Dillon Road east of the Village and a second 200,000-gallon tank further up the hill and east of Oceana Marin.

Water Treatment

The water supply is subject to several sources of contamination, including high bacteriology levels and turbidity from surface water infiltration; high natural mineral content; and possible contamination from septic systems serving the Village. Therefore, all water is treated in a single treatment plant that uses iron manganese removal system, Pall membrane filtration micro-filtration, ultraviolet light disinfection, and chlorination. All treatment is contained in the treatment plant on the hill east of the Village.

Fire Safety

Cal Water and the Tomales Fire Department routinely inspect the hydrants, which have been determined to have adequate pressure. The fire department is working with the Cal Water to maintain and upgrade older wharf hydrants.

Customer Service

Cal Water encourages consumers to contact them directly when problems arise: 707-274-6624

Media and Press Release



Technical Advisory Committee

2022 Agendas
Title Date
Technical Advisory Meeting Dillon Beach 02/11/2022

Frequently Asked Questions

Open All Questions

  • Dillon Beach was tagged by DWR as areas for water-resource planning and decision-making in rural communities. If that’s all correct, why is there being a study funded?

    The study is not funded for each area. The present study focuses only on the Dillon Beach. The Community Development Agency (CDA)/Environmental Health Services (EHS) recently received the external funding to study the environmental problems associated with current onsite wastewater system (OWTS) in Dillon Beach.

  • Why is the amount of $194,336 needed to complete a water waste feasibility study?

    No, it is an engineering study investigating the environmental issues (OWTS, Water Quality) in the Dillon beach village (DBV) specifically associated with current onsite wastewater systems in Dillon Beach. The project has comprehensive tasks starting from (i) collecting background and study area conditions; (ii) problem assessment regarding operational and environmental problems associated with the current OWTS, (iii) water quality impacts involving wet weather sampling to collect information regarding fecal indicator bacteria and other constituents (nitrogen and surfactants), groundwater testing etc., (iv) formulating wastewater alternatives including onsite upgrades, evaluating soil and site conditions etc., (v) analysis of the alternatives, (vi) public outreach, and (vii) project report.

    At the end of project, we will have an analysis and comparative review of the various project alternatives in identifying the best wastewater management alternatives for the DBV community.

  • What goes into a waterwaste feasibility study?

    This is a small-scale engineering study where the consultant will collect the background information and study area characteristics to help in identifying the reasonably possible wastewater alternatives and solving the complex environmental issues. The end goal of the study is to provide a preliminary list of range of alternatives regarding broad range of conventional and latest alternative wastewater technologies to the community.

  • How much say do the community have over what projects are produced from the study?

    The CDA heard the community concerns and priorities through various community engagement meetings (3 community meetings: Nov 2018, Jan 2019, and April 2019) and identified that the next steps for the community is to conduct the feasibility study for the old and failing septic system in the village. Therefore, we are proposing scope of work for completion of an engineering feasibility study to identify and evaluate wastewater management solutions for the DBV.

    It is a non-commitment project meaning that we are identifying the environmental issues like old, and failing septic system, water quality, etc. This is in regards to the needs assessment and capacity building. The report containing a broad range of conventional and alternative wastewater technologies, field studies, soil characteristics, groundwater quality/levels etc. will be available to the community. The project encompasses the public involvement and education activities including meetings, workshops, providing technical and other process-related information as required by the community.