Legal Question in Real Estate Law in California

If there was an assessors parcel map attached to your title insurance policy when you bought the house, it might show where the line is between your property and the public land of the street, though parcel maps are not legally binding. The only way to tell for absolutely sure would be to find the subdivision map or have a survey. Chances are about 50/50 that the fence is on the actual property line.

There is absolutely no way to tell where a property line is for such limited information. 99.5% of the time, the property line will be where the deed says it is, but deeds are written in surveyor talk and don't (usually, at least) mention streets, fences, fireplugs, or the old oak tree.

In some rural areas, such as where I live, the property line goes to the middle of the county road. Not a good deal for the property owner, especially when you decide to plant strawberries or play croquet on your land. Hmpfh. I know of one town (Ruth, Nevada, to be precise) where there was a huge town-layout survey error and the street-corner property owners found out, decades after the town was laid out, that their houses were in the street and the pavement that everyone thought was the street was where the first house in the next block should be.

There once was (and still is, to a limited extent) a so-called "agreed boundary doctrine" that said when neighbors have accepted a certain fence, or line of trees, or some other natural feature, as the boundary between their properties for a long time, AND the descriptions in their deeds are vague - perhaps referring to long-dead trees or long-disappeared monuments, then the accpted boundary will become the legal boundary, despite the deeds, because of the uncertainty of the deed descriptions. In modern California, where most properties are described with "metes and bounds" descriptions, the agreed-boundary doctrine is not used.

So, you need a survey (probably) to know for sure, although your neighbors or the tract developer might be able to make an educated guess. Also, keep in mind that parts of what you "own" might be encumbered by various easements for utilities, sidewalks, streets and roads, etc. so you might not have full use of what you theoretically own.