The Airport Overlay (APO) is an overlay district and is intended to create airport approach zoning regulations for the purpose of promoting the health, safety and general welfare of inhabitants of the county by preventing the creation or establishment of airport hazards, and thereby protecting the lives and property of users of a county airport and of occupants of the land in the vicinity of a county airport and preventing destruction and impairment of the utility of an airport and any public investment therein. Within any specific APO the specific policies, standards and regulations of the Principle Zone with which the APO is combined, are modified in accordance section 17.64.010.A - J below.

1. Development standards for APO. Development standards for the APO shall be as follows:
   1. Uses:
      1. Permitted uses: In addition to the uses allowed by the principal zone the following additional land uses shall be permitted on the airport property, subject to conformity with Federal Aviation Agency (FAA) standards applicable to the particular airport property:
         1. Accessory structures and facilities, including aircraft and aviation accessory sales;
         2. Aircraft fueling facilities;
         3. Aircraft storage, service, and repair hangars;
         4. Lighting, radio, and radar facilities;
         5. Runways, taxiways, landing strips, and aprons, grassed or paved;
         6. Terminal facilities for passengers and freight.
      2. Conditional uses: None.
      3. Prohibited uses: The uses permitted by the principal zone shall be modified as follows:
         
         Zone A: No structures are allowed;
         
         Zone B: No industries involved in flammable materials or processes, major public utility distribution centers, or places intended for the general public to gather in which a population density of greater than 50 persons per acre will occur (including hotels, motels, restaurants, bars, churches, schools, hospitals, government services, concert halls, auditoriums, stadiums, arenas, or other uses) are allowed. Maximum structural coverage shall not exceed 50% of the total land area. Clustering of development is encouraged to avoid placing structures within the zone.
         
         Zone C: Residential uses and places of public assembly should be clustered so as to avoid placing structures under the most heavily used flight patterns; (A map showing properties within the Zones A, B, and C is available for public review in the office of the Mariposa County planning department.)
   2. Minimum parcel or lot size: Same as the principal zone.
   3. Density: Same as the principal zone.
2. Use limitations. No use may be made of land within any primary surface, horizontal surface, conical surface, or transition surface, in such a manner as to create electrical interference with radio communication between the airport and aircraft; make it difficult for pilots to distinguish between airport lights and other lights, use lights which will produce glare in the eyes of the pilots using the airport, impairing pilot visibility, or otherwise endangering the landing, takeoff or maneuvering of aircraft.
3. Airport Surfaces. In order to carry out the purpose of this chapter, all land within the boundaries of the Mariposa- Yosemite Airport, and other land in the vicinity of the airport is divided into: horizontal surfaces, conical surfaces, transitional surfaces, approach surfaces and primary surfaces, the boundaries of which are on a map designated as the Mariposa- Yosemite Airport surfaces map. The Mariposa-Yosemite Airport surfaces map shall be maintained in the Mariposa County planning department and available for public examination.
4. Definitions. Due to the unique character of the district, the following definitions shall apply to the provisions contained in this Chapter and shall not affect or otherwise alter any other provisions of this Title:
   1. Airport: The Mariposa-Yosemite Airport.
   2. Airport hazard: Any structure or tree or use of land which obstructs the airspace required for the flight of aircraft in landing or taking off at the airport, or is otherwise hazardous to such landing or takeoff of aircraft.
   3. Landing area: The area of the airport used for the landing, takeoff, or taxiing of aircraft.
   4. Structure airport: Any object constructed or installed by man, including but not limited to buildings, towers, smokestacks, and overhead lines.
   5. Tree: Any object of natural growth.
   6. Imaginary Surface: A horizontal surface above which objects affect navigable airspace. The imaginary surface is established at the 2,402 feet mean sea level.
   7. Primary Surface: A horizontal surface that extends 200 feet beyond each end of the runway. The elevation at any point on the primary surface is the same as the elevation of the nearest point on the runway centerline.
   8. Transition Surface: Laterally from the primary surface to the distance where a one hundred fifty (150) foot height above the primary surface is reached on a 7:1 slope: one hundred fifty (150) feet at the outer perimeters.
   9. Horizontal Surface: The horizontal surface is established by swinging arcs five thousand (5000) feet radii from the center of the ends of the primary surface, and connecting the adjacent arcs by drawing lines tangent to those arcs. The horizontal zone shall encompass the area from the outer perimeter of the transition surface to the limits of the five thousand (5000) foot radii and tangents: the elevation of the horizontal surface shall be one hundred fifty (150) feet at all locations.
   10. Conical Surface: Outward from the outer perimeter of the horizontal surface a distance of four thousand (4000) feet on a 20:1 slope: one hundred fifty (150) foot elevation at the inner perimeter to three hundred fifty (350) foot elevation at the outer perimeter.
   11. Approach Surface: From the edge of the clear zone at the ends of the runway a distance required to intersect the horizontal zone at a 20:1 slope with the outer edges sloping outward at a 10:1 slope: one hundred fifty (150) feet at the outer perimeter.
5. Height limits. In order to protect the safety of aircraft as well as facilities on the ground the following height limitations are imposed. In areas in which the ground surface lays below the imaginary surface the height of all structures shall be limited to the elevation of the imaginary surface or 35 feet, whichever is less. In areas in which the ground surface penetrates the imaginary surface the height of all structures shall be limited to 35 feet.
6. Exception to height limitations. Nothing in this section shall be construed as prohibiting the growth, construction or maintenance of any tree or structure to a height up to twenty-five (25) feet above the surface of the land except in the primary surface.
7. Multiple coverage: Where an area is covered by more than one (1) height limitation, the more restrictive limitations shall prevail except as provided for in item F.
8. Noise standards: New residential development and major renovations to existing residential development (exceeding 50% of the value of the existing dwelling) located within the future (2010) 60-65 CNEL contours (as contained in the Mariposa-Yosemite Airport Comprehensive Land Use Plan) shall provide a noise analysis of their project site to determine the level of noise insulation required to reduce the indoor noise levels to below 45 CNEL and shall incorporate the noise insulation into dwelling construction. The Mariposa-Yosemite Airport noise map shall be maintained in the Mariposa County planning department and available for public examination.
9. Amendments to general plans, specific plans, and zoning ordinances: Any proposed amendment to a general plan, specific plan, or zoning ordinance that affects land uses within the airport influence area boundary must be submitted to the ALUC for a determination of consistency with the Airport Land Use Plan. The ALUC shall provide its findings regarding project consistency to the county reviewing authority prior to public hearings on the project.