Hi Mary, Lynn is right about the area and the method for answering your question. From what I can tell the property is in the Williamson Act, per the listing agents. http://www.conservation.ca.gov/dlrp/lca/Pages/Index.aspx
The purpose of this act is to reduce the property taxes associated with land that is dedicated to open space or agricultural pursuits. There are very specific limitations as to development. Property can be withdrawn from the act over a period of at least ten years but of course would still be subject to zoning and planning restraints. The benefit to the farmer or rancher of course is reduced holding costs. As with any country property, issues of water, zoning, taxation, boundaries and sewage disposal are complicated and need to be fully explored by the country property buyer, hopefully with an agent who is experienced in those matters.