This can be difficult, but we have several suggestions:
We can provide you with a copy of the Assessor's map, which will show an outline of your property according to the dimensions on your deed.
In rural areas, or in other areas where there may not be a regular lot pattern, you may have to reference an existing or obtain a partial or full survey from a licensed land surveyor or civil engineer.
In urban areas, you may sometimes determine the location of your front lot line once you know the width of the right of way in front of your property (a staff member at the counter can help you to find out the width). For example, suppose the width of the right of way is 50 feet. Your front property line will be located approximately one half that distance, or 25 feet, from the middle of the right of way.
Fence lines are not necessarily a good indicator of property lines and should not be relied upon for drawing plans and determining setbacks.
If in doubt, hire a licensed land surveyor to prepare a survey. Depending on the type of project you are proposing, you may need to obtain a full or partial boundary survey of your property for submittal with a planning or building permit application. A boundary survey is required for work within five feet of a required minimum setback.
To to find a surveyor that works in your area, you may search the California Land Surveyors Association.