Legal Question in Real Estate Law in California

You have one of three options. You can build your fence without prior notice to the neighbors, thereby offending them. This course of action may or may not be legal; the only certainty is that it will enrich at least two lawyers in your town. Second, you could obtain written permission (a license) to construct the fence and maintain it at your expense, or at shared expense, and to use the 30 feet of land, for X number of years. Third, you could buy 30 feet of the easement from your neighbor, and have a revised easement recorded.

If that is all there is to the legal description it is unfortunately vague. It might be able to be interpreted for certain by reference to the parcel maps, but in the abstract, I can't give you a reliable answer.

The description doesn't seem "unfortunately vague" to me. Also, it may be supported by a map, but in any case it is adequate to describe the easment.

I agree with Mr. Stone about negotiating before fencing.

If push comes to shove, however, I think you would prevail, on the strength of the principles discussed by the Court of Appeal in Scruby v. Vintage Grapevine, Inc. (1995) 37 Cal.App.4th 697. Find the case at your county law library and give it a read. I think it supports your plan to fence the unused portion of the easement so long as it doesn't interfere with the intended purposes.