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Marin County Land for Sale: Zoning, Septic and Coastal Permits

By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.

Land for sale in Marin County is mostly found in the unincorporated areas, especially West Marin, where the County of Marin sets the rules through its Countywide Plan, its Development Code and, along the coast, its Local Coastal Program. What you can build on a Marin lot or ranch depends far more on zoning density, coastal permits, septic feasibility and recorded easements than on acreage. Before you price a parcel, find out which of those rules apply and what they allow.

Marin’s undeveloped land is a mix of in-town lots, hillside parcels above the Highway 101 towns, and ranches in the Nicasio, Tomales and Point Reyes areas, many of them under agricultural easements. This guide covers how the county’s land-use system works, the coastal permit process, wells and septic, easements and contracts, hazards and costs, and how to sell land here. Our Marin County guide covers the county’s towns and housing market.

Marin County land for sale

Marin County market report

Who sets the rules for a Marin parcel?

Start with jurisdiction. Inside a city or town such as San Rafael, Novato or Mill Valley, that city’s zoning and design rules apply. Everywhere else, the County of Marin’s Community Development Agency handles zoning, design review, building permits and environmental health.

Document	What it does	Where it applies
Marin Countywide Plan	Sets land-use designations and density ranges; last amended in January 2023, including the 2023 Housing Element	Unincorporated county
Development Code (Title 22)	Zoning districts, design review, use permits, variances, subdivisions	Unincorporated county outside the coastal zone
Local Coastal Program: Land Use Plan and Coastal Zoning Code (Title 20)	Coastal policies and the standards for coastal permits	Unincorporated coastal zone
Community and area plans	Local policies; the county has 22 of them	Specific communities, such as the Nicasio Valley

The county’s online Zoning and Property Tool shows a parcel’s zoning and plan designation. For a deeper look, the Planning Division offers a Property Information Packet with a parcel’s permit history, a two-hour Planning Consultation for smaller projects, and a Preapplication review for larger ones.

Countywide Plan designations and agricultural zoning

Rural Marin land is typically designated for agriculture in the Countywide Plan and zoned in one of the county’s agricultural districts. A 2026 county design review record for a 45-acre ranch parcel in Nicasio shows how the two work together: the land is designated AG1, agriculture at a residential density of one unit per 30 to 60 acres, and zoned ARP-60, the Agricultural, Residential Planned district at one unit per 60 acres.

Two points follow for buyers:

Density, not size, sets the house count. A 100-acre parcel zoned at one unit per 60 acres supports one home, not two. Approvals can also fix where building goes: the Nicasio project placed its accessory buildings inside a designated building envelope.
Design review is common. That Nicasio project, two barn-scale accessory buildings with a new septic system and a fire truck turnaround, needed design review under Development Code section 22.42.020(A), because it could not be exempted.

The Ridge and Upland Greenbelt

The Countywide Plan also designates a Ridge and Upland Greenbelt: the county’s mapping describes it as the plan’s “visually prominent ridgelines,” also called community separators. If a hillside parcel falls inside it, expect siting, height and visibility from public areas to be central questions in review, and ask the Planning Division which plan policies apply before you design a house or road.

Building in the coastal zone

Much of West Marin lies in the unincorporated coastal zone, including communities such as Muir Beach, Stinson Beach, Bolinas, Olema, Point Reyes Station, Tomales and Dillon Beach. There, the Local Coastal Program applies. Its Land Use Plan was adopted by the Board of Supervisors in 2018 and certified by the California Coastal Commission on February 6, 2019.

Coastal agricultural land

On land zoned C-APZ, the Coastal Agricultural Production Zone, the plan sets these limits:

A maximum density of one agricultural dwelling unit per 60 acres, which the plan calls a maximum, not an entitlement.
A combined farmhouse size limit of 7,000 square feet per farm tract, plus 540 square feet of garage and 500 square feet of farmhouse office.
Intergenerational homes at 60 acres each: the first needs no use permit, a second needs one, and the coastal zone has a cap of 27 such homes.
Clustered development, roads and structures covering no more than 5% of gross farm acreage, to the extent feasible.
For land divisions and non-agricultural conditional uses, a permanent agricultural conservation easement over the undeveloped land and an Agricultural Production and Stewardship Plan keeping at least 95% of the land in agriculture or resource protection.

Development is allowed only where there is adequate water, sewage disposal and road access, and C-ARP land must cluster development to protect natural resources and coastal views.

Coastal permits and exclusions

Most development in the coastal zone needs a Coastal Permit, which is discretionary, usually involves a hearing before the Deputy Zoning Administrator, and in some areas can be appealed to the Coastal Commission. The Coastal Commission has approved categorical exclusions for some work. A new single-family home on a vacant legal lot is excluded only in specific places: the Point Reyes Station community expansion area, Olema, Old Dillon Beach, Tomales and Oceana Marin, each with conditions. Additions are excluded only up to 50% of existing floor area or 1,000 square feet, whichever is less, and not for structures built before 1930 or in listed historic areas.

Exclusions never apply on tidelands, wetlands, beaches or lots next to a beach, and an exclusion must be approved before the county issues building, septic or well permits. Our guide to buying coastal property in Sonoma and Marin goes further, and town guides such as Tomales, Olema and Bolinas cover local water and sewer limits.

Septic, wells and water

Most of West Marin, and pockets of east Marin, rely on septic systems, and septic feasibility is often what decides whether a lot is buildable. Marin County Environmental Health Services handles both septic systems and private wells.

Proving a septic system can work

Request a site evaluation from Environmental Health Services.
Run percolation testing with county staff present; some sites also need wet-weather testing, which the county does only during its testing season.
Obtain a construction permit, pass county inspections and receive a certificate of installation.
For alternative systems, hold an operating permit for the life of the system, with annual renewal and professional monitoring.

Properties in the coastal zone or a Stream Conservation Area may need additional permits. The county’s online records system lets you search past septic and well records for a parcel.

The LAMP update

Marin is rewriting its septic regulations as a Local Agency Management Program, or LAMP, which needs approval from the Regional Water Quality Control Board and the Board of Supervisors. The county says its program still runs on regulations and code last amended in 2011, and it is targeting adoption at the end of 2026. Current rules size systems at 150 gallons per day per bedroom, with a 30% reduction for water-saving fixtures; the county is reviewing whether to lower design flows and allow more alternative systems, which could change what some lots can support. Our Marin septic systems guide follows the update.

Wells

Drilling a water well needs a county permit. If the water will be used for human consumption, you also need a permit to operate the well as a domestic water supply, under performance, pumping and quality standards in County Code chapter 7.28. Wells must be at least 50 feet from any sewer line and 100 feet from animal enclosures, and the county’s dry-weather water testing season opens July 15. Where a water district serves the area, ask the district whether a new connection is available and on what terms. See our guide to well and septic inspections in Napa and Marin.

Easements and contracts that limit ranch land

A large share of Marin’s farmland carries recorded restrictions, so read title closely.

MALT easements. The Marin Agricultural Land Trust holds 99 agricultural conservation easements covering 59,028 acres, bought to keep land in farming and ranching. Owners must get MALT’s approval before adding new buildings or roads.
Conservation easements in general. Under California Civil Code section 815.2, a conservation easement is perpetual, is an interest in the land itself, and has the specific limits written in the recorded document.
Williamson Act contracts. Under the California Land Conservation Act of 1965, the owner agrees to keep land in agricultural or open-space use and is taxed on that use rather than full market value. See our Williamson Act guide for how contracts, nonrenewal and cancellation work.

Ask for the recorded easement or contract in the first days of escrow. It may fix building envelopes, ban further division, or require agricultural use, and it binds you as the next owner. The Nicasio guide shows how these restrictions play out on inland ranches.

Hazards, access and costs to budget

Fire, flood and access shape both the permit and the insurance.

Fire: Look up the parcel in CAL FIRE’s Fire Hazard Severity Zone viewer. The State Responsibility Area map took effect April 1, 2024, and the Local Responsibility Area maps were released in four phases in February and March 2025. Defensible space and home hardening are the owner’s responsibility.
Flood: Check FEMA’s Flood Map Service Center for low-lying and creekside land, including near Tomales Bay and the coast.
Access: Confirm legal and physical access, road maintenance and fire-truck turnaround needs; our Marin property access and improvement review walks through the checks.

Fees add up on a new house. The county charges an Affordable Housing Impact Fee on residential development over 2,000 square feet, at $5 or $10 per square foot of conditioned floor area, a Road Impact Fee of 1% of building permit valuation on projects of $10,000 or more, and a 10% Long Range Planning surcharge on selected permit fees. Transfer tax is $0.55 per $500 of value countywide (that is, $1.10 per $1,000), with San Rafael adding its own city tax. In Marin, the seller customarily pays transfer tax, but it is negotiable.

Building a house in West Marin: the usual sequence

Confirm the lot is legal and get its zoning, plan designation and coastal status from the county.
Prove septic and water with a site evaluation, percolation tests and a well or water-district answer.
Review easements and title for MALT, Williamson Act or other recorded limits.
Apply for planning approvals: design review, a coastal permit or exclusion, and any use permit. The county aims to decide completeness within 30 days of submittal. For a project found exempt from CEQA, the state Permit Streamlining Act generally gives the county 60 days from that determination to approve or deny it (Government Code section 65950).
Apply for building, septic and well permits, then build before the approval expires; planning permits not vested within three years generally expire.

On a tight lot or a remodel of an existing home, design review rules vary by town; see renovation and design review in Marin.

Selling land in Marin County

Buyers of Marin land pay for certainty. Before listing, gather the parcel’s zoning and plan designation, any Property Information Packet, septic site evaluations and percolation results, well logs and test results, surveys, easement documents and any planning approvals still in force. A lot with a documented septic design and water source is a different product from one with neither, and pricing should reflect which you have. Our Marin County selling guide covers the rest of the sale process.

This is general information, not legal advice; talk to a California land use attorney and a licensed septic designer or engineer about a specific parcel.

Questions people ask

Can I build a house on land in West Marin?

Often, but not always. You need a legal lot, zoning that allows a home at the parcel’s size, a workable septic system and water source, and in the coastal zone a Coastal Permit or a categorical exclusion.

What does ARP-60 zoning mean in Marin?

It is the Agricultural, Residential Planned district at a density of one unit per 60 acres. Other agricultural districts set their own densities, so confirm a parcel’s district and any land-division conditions with the Planning Division.

How big can a farmhouse be on coastal agricultural land?

On C-APZ land, the Local Coastal Program caps combined farmhouse space at 7,000 square feet per farm tract, plus 540 square feet of garage and 500 square feet of office.

Do I need a Coastal Development Permit to build in Marin’s coastal zone?

Usually. New homes on vacant legal lots are excluded only in parts of Point Reyes Station, Olema, Old Dillon Beach, Tomales and Oceana Marin, and the exclusion still needs county approval.

What is the Ridge and Upland Greenbelt?

It is a Countywide Plan designation for visually prominent ridgelines, also called community separators. Parcels inside it should expect close review of where and how high you build.

How do I know if a lot will pass a septic test?

Only testing tells you. Hire a qualified septic professional to schedule a county site evaluation and percolation tests, and make the purchase contingent on the results.

What is the Marin LAMP update?

It is the county’s rewrite of its septic rules as a Local Agency Management Program, targeted for adoption at the end of 2026 and subject to Regional Water Board approval. It may change design flows and expand alternative systems.

Can I drill a well on Marin land?

With a county well permit, and a separate permit to operate it if the water is for drinking. The well must meet county setback, yield and quality standards.

What is a MALT easement?

A permanent agricultural conservation easement held by the Marin Agricultural Land Trust. It stays with the land, and new buildings or roads need MALT’s approval.

Can I subdivide land in Marin County?

Only within the zoning density and with county approval; the county’s application guide lists a tentative map for creating more than four lots. On coastal agricultural land, a division also requires a permanent agricultural easement and a stewardship plan.

Is any Marin land under the Williamson Act?

It can be. A contract keeps land in agricultural or open-space use in exchange for a lower assessment, so ask the seller, check the title report and tax bill, and get a copy of any contract early in escrow.

What fees come with building a new home in unincorporated Marin?

Expect planning and building fees, plus an Affordable Housing Impact Fee on homes over 2,000 square feet, a Road Impact Fee of 1% of permit valuation and a 10% Long Range Planning surcharge on selected fees.

Who pays transfer tax on Marin land?

The seller customarily pays the county’s $1.10 per $1,000, but it is negotiable. San Rafael adds a city transfer tax inside its limits.

Thinking about a homesite or ranch in Marin, or selling one? We can help you gather the zoning, septic and easement records before you commit. Contact Diamond Real Estate Group to discuss a parcel.

Sources & notes

Last reviewed October 2026 by Matthew Martinez.