Blog · October 14, 2026 · California
Using the Martinez Plat Map
Lots in Martinez trace back to recorded plats filed with the county.
Main page: Contra Costa County, CA GIS & Parcel Viewer (official map link, county facts and neighboring maps).
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When a listing near Orinda mentions a lot number, you'll need the Martinez plat map to make sense of it. This Martinez guide covers: where plats are filed, how a plat differs from a parcel map, and what to look for on the sheet.
Who keeps the Martinez plat map
For a lot in Martinez, the deed or parcel record often names the subdivision and plat reference; that makes the request quick.
The free map to start with
Lots and tracts near Pleasant Hill appear on the Contra Costa County parcel viewer, a viewer that needs no account. When a rural tract has no street number, zoom in from Lafayette and select the outline. On ground around Hercules, the record panel typically gives the owner of record, assessed acreage, a parcel ID and in many cases the last transfer.
City limits and county records
Martinez sits in Contra Costa County, California, and the county assessor maps its lots. As the county seat, Martinez hosts the courthouse, which puts the County Recorder close by. For a tract near Concord, city or town hall handles things like zoning, permits and utilities within town limits, while the county keeps the tax map. Acreage past the town limits out by Walnut Creek generally falls under county rules instead.
When a parcel crosses a boundary
Contra Costa County meets Alameda County, Marin County, Sacramento County, San Francisco County, and San Joaquin County, and each of those keeps its own parcel map. Ground near Orinda that runs to the line can be split in two county records, so open the adjacent map as well. On ground around Pleasant Hill, our state page lists every neighboring county map for California.
Plat map vs. parcel map
When the two disagree for a lot near Hercules, trust the recorded documents over the GIS layer.
Reading the plat sheet
Recorded easements around Hercules can block a shed or pool; read the notes on the sheet.
Legal descriptions in California
California follows the Public Land Survey System, which means a tract near Orinda is described by section, township and range. A standard section is about one square mile, roughly 640 acres, and a township holds 36 of them, though corrections make some sections near Hercules odd-sized. Copy the legal description from the record for the parcel near Orinda before you request a deed or survey.
A word on accuracy
Acreage on the record is an assessed number; just a licensed surveyor sets the real lines on land around Orinda. For a home near Orinda, records update in batches, so a deed recorded last month might lag behind.
Recorded documents worth pulling
For anything that matters, request the recorded deed from the County Recorder; the parcel map near Hercules only summarizes it. Inherited tracts near Hercules may sit on many deeds, so a title company earns its fee before a purchase.
Using it on a phone
The parcel map usually runs in a mobile browser, useful out on a road near Orinda, so load it before you lose signal. A screenshot of the parcel near Hercules with its ID is a good backup.
Who handles what
Deeds, mortgages and recorded plats for land near Hercules sit in the index kept by the County Recorder, often with an online index. Building or septic questions for a lot near Orinda need the planning or permitting office, town or county, depending on location.
Land outside a subdivision
Rural land near Concord that was never subdivided is often described by metes and bounds or survey description; look for a recorded survey for land near Hercules.
Amended plats
Lots near Concord can be combined or reconfigured by a replat, search the index for replats of the same subdivision; street vacations near Pleasant Hill show up in the records too.
Places you'll see on the map
Martinez holds the county offices, where most land records are kept. You'll also find Pleasant Hill, Concord, Lafayette, and Walnut Creek, each with its own cluster of lots. Roughly 1,155,025 people live in Contra Costa County (Census estimate, 2023) on roughly 717 square miles. Landmarks such as Clayton-Marsh Creek-Greenville Fault, San Pablo Dam Reservoir, and Mount Diablo State Park help you orient on the aerial around Walnut Creek.
Ordering the Martinez plat map
If the land is near Orinda, some counties put plat images online, while others require a visit or a request; small fees are common.
Frequently asked
How do I read lot and block around Concord?
For a home near Hercules, the description sends you to a specific recorded plat, so pull that plat for dimensions.
How do I split a lot near Hercules?
Short answer: lot splits in the city go through the planning office; ask staff about the process for land near Hercules.
Is the Martinez plat map the same as the county GIS?
If you're looking near Lafayette, GIS parcels are tax drawings, and the recorded plat is the legal document; trust the plat when they differ.
Where can I find the Martinez plat map?
For most people, recorded plats near Hercules are filed with the County Recorder.
Is there an app for the parcel map near Lafayette?
No app is needed for most county viewers; load it before you lose coverage near Walnut Creek.
Open the official Contra Costa County, CA parcel map See it in the Platbookmapper directory
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey, especially for fences, setbacks, or boundary disputes.