Union City City Zoning Code
CHAPTER 18
92 OPEN SPACE OS ZONING DISTRICT
§ 18.92.010 Purpose.
The purpose and intent of this district is to:
A.
Provide adequate recreation and open space lands for the needs of the population, present and future;
B.
Preserve and protect open space lands as a limited and valuable resource;
C.
Discourage premature and unnecessary conversion of open space land to urban areas in order to discourage noncontiguous patterns of development which unnecessarily increase the cost of community services to community residents;
D.
Prevent incompatible development of areas which should be preserved or regulated for scenic, historic, or conservation purposes;
E.
Insure the retention of certain lands in their natural or near natural state, so as to protect the public health, safety, and welfare of the community from natural disasters such as fire, flood, erosion, seismic activity, etc.
Provisions of this district also provide for the reasonable use of open space land while at the same time preserving and protecting its inherent open space character. |
(Ord. 55.117-74 § 5 (18.1), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.020 Definitions.
Lands defined herein constitute lands which shall be included in the Open Space Zone. As used in this chapter, unless otherwise apparent from the context, the following definitions shall apply:
"Conservation" or "natural resource"
includes but is not necessarily limited to streams, watersheds, ground water recharge, soils, wildlife habitat as defined herein, special land forms, and natural vegetation.
"Conservation of land" or "natural resource land"
means land which possesses or encompasses conservation or natural resource lands, the use or recovery of which can best be realized by restricting the use of the land as provided by this chapter.
"Hazardous lands"
means lands hazardous to the public health, safety, and welfare (evidence of faults, folding, ground movement, slopes, unstable soil bearing valves, natural fire areas, areas susceptible to floods and other similar conditions).
"Open space district"
means any area of land or water designated "OS" and subject to all the terms and regulations of this chapter.
"Open space land"
means any parcel or area of land essentially unimproved or in its natural state devoted to open space use as defined herein, which is designated in the open space element for an open space use.
"Open space use"
means the use of land for:
1.
Public or private recreation;
2.
Enjoyment of scenic beauty;
3.
Conservation or use of natural resources;
4.
Open field cultivation;
5.
Orderly structuring of urban development.
"Recreation lands"
means any area of land or water susceptible to recreation or scenic uses.
"Scenic lands"
means any area of land or water which possesses scenic qualities worthy of preservation.
"Unserviceable lands"
means lands which, because of their location, cannot be economically maintained or serviced by the City.
"Water supply lands"
means lands including but not limited to watershed or ground water recharge areas.
"Wildlife habitat"
means any area of land or water valuable or necessary to the preservation or enhancement of wildlife resources.
(Ord. 55.117-74 § 5 (18.2), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.030 Regulations established.
The following specific regulations and the general regulations set forth in this title shall apply to all OS districts.
(Ord. 55.117-74 § 5 (18.3), 1974; Ord. 670-06 § 3, 2006; Ord. 672-06 § 2, 2006; Ord. 903-22 § 4, 2022)
§ 18.92.040 Permitted uses.
All permitted uses, excluding uses devoted solely for the production of food or fiber within the district, shall be subject to approval for development, construction, or improvement as provided in Chapter 18.76.
A.
Outdoor recreation, including, but not limited to, parks and other areas of passive recreation usage in a natural or near natural state. Trails and other suitable corridors and areas for the preservation of outstanding scenic, geologic, historic, and cultural value.
B.
Agricultural uses as defined in Chapter 18.48, excluding the following:
1.
Greenhouses;
2.
Commercial feed lots;
3.
Commercial slaughtering of animals;
4.
Commercial packaging, processing, treatment, or storage of produce or meat products;
5.
Other uses which violate the purpose of this chapter, as determined by the City Council.
C.
Outdoor nature laboratories, natural wildlife sanctuaries, and similar facilities.
D.
Water supply lands, including but not limited to watershed and ground water recharge areas.
E.
One-family (detached) dwellings subject to Section 18.32.020.
F.
Archeological digs.
G.
Accessory structures and accessory uses.
H.
Temporary contractor yards, for public projects, on publicly owned properties.
(Ord. 55.117-74 § 5 (18.4), 1974; Ord. 670-06 § 3, 2006; Ord. 2026-002, 1/27/2026)
§ 18.92.050 Conditional uses.
All conditional uses within this district shall be subject to approval for development, construction, or improvements as provided in Chapter 18.56.
A.
Utility uses, i.e., small substations and/or transmission easements, which are low intensity (vehicle activity, land coverage, structural) and expressly conform to the purpose of the Open Space District.
B.
Educational, charitable, research and philanthropic uses, which are of low intensity (vehicle activity, structural) and expressly conform to the purpose of the Open Space District.
C.
Active or organized recreational uses including, but not limited to, riding academies, clubs, stables, country clubs, guest ranches and golf courses.
D.
Outdoor zoos, botanical conservatories, or botanical gardens.
E.
Accessory structures and accessory uses.
F.
Commercial tree farming operation.
(Ord. 55.117-74 § 5 (18.5), 1974; Ord. 670-06 § 3, 2006; Ord. 731-10 § 2, 2010)
§ 18.92.060 Walls, fences, and hedges.
Walls, fences and hedges exceeding six feet in height shall not be permitted in required yards.
(Ord. 55.117-74 § 5 (18.6), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.070 Area and yard standards.
Table 18.92.070, Area and yard standards — Open Space (OS) Districts, prescribes the area and yard standards for the Open Space (OS) District.
Table 18.92.070 Area and yard standards — Open Space (OS) District | |
|---|---|
Standard | |
Site area, Minimum | 10 acres |
Public Lands – No minimum for sites owned by a public agency | |
Hazards Lands – No minimum for sites designated open space due to natural hazards | |
Front yard setback, minimum | 100 feet |
Sites under 10 acres – 25 feet | |
Public Lands – No minimum for sites owned by a public agency | |
Side yard setbacks, minimum | 100 feet |
Sites under 10 acres – 15 feet | |
Public Lands – No minimum for sites owned by a public agency | |
Rear yard setback, minimum | 100 feet |
Sites under 10 acres – 25 feet | |
Public Lands –No minimum for sites owned by a public agency | |
(Ord. 55.117-74 § 5 (18.7), 1974; Ord. 670-06 § 3, 2006; Ord. 2026-002, 1/27/2026)
§ 18.92.080 Maximum building coverage.
Maximum impervious area and building coverage shall be 6%.
(Ord. 55.117-74 § 5 (18.8), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.090 Building height limit.
Residential buildings shall not exceed two stories, or 25 feet in height.
(Ord. 55.117-74 § 5 (18.9), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.100 Off-street parking.
Three vehicle spaces shall be required for each dwelling unit.
(Ord. 55.117-74 § 5 (18.10), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.110 Geologic and soils investigation report.
All applications for a use permit shall be accompanied by a combined in-depth geologic and soil investigation report prepared by a registered geologist, certified by the State of California as an engineering geologist, and by a licensed soils engineer. Such report shall be based on surface, subsurface, and laboratory investigations and examinations and shall fully and clearly present:
A.
All pertinent data, interpretations and evaluations;
B.
The significance of the data, interpretations and evaluations with respect to the actual development or implementation of the intended land use and with respect to the effect upon future geological processes, both on and off the site;
C.
Recommendations for any additional investigations that should be made.
Such reports may be required by the City Engineer for permitted uses in areas of questionable or unknown geological hazard as determined by the City. All costs and expenses incurred as a result of this section, including the cost and expense of an independent review of the materials submitted hereunder by qualified persons retained by the City shall be borne by the applicant. |
(Ord. 55.117-74 § 5 (18.11A), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.120 Soil erosion and land management.
No site development review plan or use permit shall be approved unless it includes soils analysis, erosion, and sediment control measures in accordance with adopted procedures, technical standards and specifications of the Soil Conservation Service and/or as prescribed by the City. The applicant shall bear final responsibility for the installation and construction of all required erosion control measures according to the provisions of said standards and specifications.
(Ord. 55.117-74 § 5 (18.11B), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.130 Building permits.
No building permit shall be issued in the Open Space District unless all needed erosion control measures have been completed or substantially provided for in accordance with said standards and specifications.
(Ord. 55.117-74 § 5 (18.11C), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.140 Landscaping.
The existing natural vegetation and land formations shall remain in a natural state unless modification is found to be necessary for a specific use allowed herein under the site development review or use permit procedure. Imported landscaping, as may be necessary and required, shall consist of indigenous species and/or species determined to be ecologically adaptable and compatible with the existing ecosystem.
(Ord. 55.117-74 § 5 (18.11D), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.150 Tree removal.
Removal of live trees of six inches or more in diameter at the base, shall be prohibited, except with the granting of site development review, use permit or approval of Director as applicable.
(Ord. 55.117-74 § 5 (18.11E), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.160 Access to road areas.
Roads, tracks, driveways, trails and other runways for automobiles, trucks, buses, motorcycles, or other wheeled vehicles shall not be developed except upon the approval of site development review or a use permit, as applicable. No such approval shall be granted except upon finding that the purpose for which the roads, tracks, driveways, trails, or runways as proposed, is essential for the establishment or maintenance of a use which is expressly permitted herein and that the design and location of the proposed roads, tracks, trails, or runways will be compatible with the terrain and the purpose of the Open Space District. The use of all roads, tracks, driveways, trails, or runways existing at the time of the adoption of this chapter, which have been established contrary to law, shall be terminated.
(Ord. 55.117-74 § 5 (18.11F), 1974; amended during 1990 republication; Ord. 670-06 § 3, 2006)
§ 18.92.170 Grading.
No grading shall be authorized except upon the approval of site development review or use permit as applicable. No such approval shall be granted except upon finding that the purpose for which the grading is proposed is essential for the establishment and maintenance of a use which is expressly permitted herein and that the design, scope and location of the grading proposed will be compatible with adjacent areas and will result in the least disturbance of the terrain and natural land features.
(Ord. 55.117-74 § 5 (18.11G), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.190 Substandard lots.
Any parcel of land not meeting the area or dimension requirements of this chapter shall be deemed a lawful building site if such parcel was a lawful building site on the effective date of the ordinance codified in this chapter. All other requirements of this chapter shall apply to any such parcel.
(Ord. 55.117-74 § 5 (18.11I), 1974; Ord. 670-06 § 3, 2006)
§ 18.92.200 (Reserved)
Note: Former § 18.92.200, Public lands, derived from Ord. 55.117-74 and Ord. 670-06, was repealed by Ord. 2026-002, 1/27/2026.