Legal Question in Real Estate Law in California

Re: Neighbors Fence

Civil Code section 841 covers boundary fences between neighbors. It says neighbors are "mutually bound equally to maintain the boundaries and monuments between them and the fences between them" unless one of them chooses to let his landlie without fencing" and so on.

In addition, Civil Code section 832 covering "lateral and subjacent support" may apply to your situation, or, if there is erosion due to non-natural causes such as careless development of an uphill property, you may have a claim for damages. California law regarding water runoff and erosion is largely case law (made by judges rather than the legislature), but it can be summarized by saying it relies heavily on fairness and reasonableness tests.

Without being able to see the situation first-hand, I can only speculate as to the probable outcome were this matter to go to court along with testimony from experts, but you make it sound as though the neighbors are primarily liable.

With half of $4,000 at stake, I think you should have the situation looked at "on the ground" by a professional. A mixture of contractor and attorney knowledge seems to be required. Probably it would be best to start with an attorney who has practical experience in outdoor, real-world land-development and land-use disputes.

You can negotiate with the couple who are in possession but before you agree to or sign anything make sure your deal is with either the actual owner or someone with full authority to bind the owner.