In the Napa-Sonoma wine growing region, as in many areas of California, land values are high. Non-agricultural development is often restricted. A storage warehouse reduces the land available to grow grapes, impacts open space and natural habitats, and precludes other land uses. Land-use regulation in California places limitations on the types and locations of land development. Many land use restrictions and permitting requirements do not apply to underground space. As of 2004, there were an estimated 130 to 150 caves used for wine aging, barrel storage, and tasting rooms in Northern California.
