In order to classify, regulate and restrict the use of land, buildings and structures; to regulate and restrict the height and bulk of buildings; to regulate the area of yards and other open spaces about buildings; and to regulate the intensity of land use, the incorporated area of Alton is divided into districts as follows:

   Conservation Districts

   CR, Conservation/recreation

   Residential Districts

   R-1, Single-family residential

   R-2, Single-family residential

   R-3, Mixed single-family residential

   R-4, Multiple-family residential

   R-6, Manufactured home residential

   Institutional Districts

   HE, Higher education

   MED, Medical

   Commercial Districts

   C-1, Neighborhood commercial

   C-2, General commercial

   C-4, Downtown commercial

   C-5, Heavy commercial

   MR, Marina recreation

   Mixed Use Districts

   MUT, Mixed use transportation

   Industrial Districts

   M-1, Light industrial

   M-2, General industrial

   M-3, Mining

   M-4, Planned business park

(Ord. 6734, 6-11-2003; amd. Ord. 7333, 10-24-2012)

   A.   Boundaries: The boundaries of the various zoning districts are hereby fixed and established as shown in the accompanying zoning map. This zoning map is on file in the office of the city clerk of the city of Alton. This map is hereby adopted and made a part of this zoning ordinance as if the matters and information set forth by said map were fully described herein.

   B.   Measurement Of Boundaries: The boundaries of the various districts as shown on the zoning map shall be determined by the boundaries as shown and outlined thereon and when not clearly so determined, by use of the scale shown on said map unless actual dimensions are noted. Scale and field measurements and map dimensions shall be figured from the centerline of streets, highways, alleys and railroad rights of way as appropriate. Where uncertainty exists as to the exact location of said boundaries, the following rules shall apply:

      1.   Centerline As Boundary: Where district boundaries lie on or within streets, highways, road rights of way or railroad rights of way, the district boundaries shall be the centerline of the same.

      2.   District Boundaries Which Bisect Blocks: Where district boundary lines approximately bisect blocks, the boundaries shall be the median lines of such blocks between the centerline of boundary streets.

      3.   District Boundaries Dividing Parcels Of Land: In subdivided property or where a district boundary divides a subdivided lot, the location of such boundary, unless the same is indicated by dimensions, shall be determined by the use of a scale appearing on the district map. Where a district boundary divides a platted lot, the zone classification of the greater portion shall prevail throughout the lot.

      4.   Action In Case Of Uncertainty: In case any further uncertainty exists, the board of appeals shall interpret the intent of the zoning map as to the location of such boundaries.

      5.   Street And Right Of Way Abandonments: Where a public road, street, alley or other right of way is officially vacated or abandoned, the regulations applicable to the property to which it reverted shall apply.

      6.   Excluded Areas: Unless areas are classified on or by the official zoning map of the city of Alton, or the appropriate classification can be established by the rules above, such areas shall be considered to be classified as R-1, single-family residential district, until such time as the land is rezoned by the city council.

      7.   Amendment To The Official Zoning Map: No changes or amendments to the official zoning map shall be initiated, except in compliance and conformity with all procedures and requirements of this zoning ordinance. It shall be unlawful for any person to make any unauthorized change in the official zoning map.

   C.   Annual Publication: In accordance with state law, if any changes are made in the zoning districts or regulations during a calendar year, the city clerk shall publish the official zoning map of the city not later than March 31 of the following year.

   D.   Zoning Of Annexed Areas: Any territory hereafter annexed to the city shall have a zoning classification indicated in the annexation ordinance. If such classification is not indicated in the annexation ordinance, the land shall automatically be zoned as R-1, single-family residential district, until duly changed by an amendment to this zoning ordinance except under the following conditions:

      1.   The city council, with the recommendation of the plan commission, may annex any territory as any other zoning district or districts herein established if all legal requirements for zoning the property at the time of the annexation are recorded.

      2.   Any existing agricultural area within Madison County of five (5) acres or more may be annexed to the city as CR, conservation/recreation district, without a public hearing. (Ord. 6734, 6-11-2003)

It is the intent of this zoning ordinance to permit certain uses, not otherwise illegal, to locate in specified zoning districts, either as a permitted use or a special use. (Ord. 6734, 6-11-2003)

   A.   NAICS Manual: Most land uses are listed according to their code number assigned by the "North American Industry Classification System" (NAICS) manual (United States version) published by the office of management and budget. This manual is adopted by reference and shall be consulted if there is any question concerning whether a particular land use is allowed in a zoning district. The land uses described in this zoning ordinance are based on descriptions, definitions, and codes contained in the 2012 version of the NAICS manual. A copy of the 2012 NAICS manual is on file in the office of the city clerk. (Ord. 6734, 6-11-2003; amd. Ord. 7438, 12-17-2014)

   B.   Permitted Uses: No structure shall be erected, constructed, reconstructed or structurally altered, nor shall any structure or land or combination thereof be used, unless the use to which the structure and/or land is to be put is listed in the permitted use section of the applicable zoning district and the use fully complies with all of the applicable district regulations, except for nonconformities, accessory uses and special uses.

   C.   Special Uses: No special use, as designated within this zoning ordinance, shall hereafter be established unless such use has been approved pursuant to the provisions of chapter 11 of this title. Any existing use which was a permitted use or granted a special use prior to the adoption of this zoning ordinance and which is designated as a special use by this zoning ordinance may continue as if it were approved as a special use. However, if such use is changed to a nonconforming use by rezoning, such use must thereafter comply with section 11-3-9 of this title.

   D.   Uses Not Specifically Listed: In the event a particular use is not listed anywhere in this zoning ordinance, is not within the same "North American Industry Classification System" (NAICS) code as any permitted or special use, and such use is not an accessory use, it shall be considered to be not allowed within the city. Questions concerning such uses may be referred to the board of appeals. (Ord. 6734, 6-11-2003)

In order to carry out the purpose and intent and provisions of this zoning ordinance, size and dimension criteria for particular zoning districts are hereby established. Such size and dimension criteria shall be applied in accordance with this section and other applicable provisions of this zoning ordinance.

   A.   Lot Size Requirements:

      1.   Reduction Of Lot Size Or Yards: No lot or yard existing on the effective date of this zoning ordinance shall thereafter be reduced in size, dimension, or area below the minimum requirements set out herein, except by reason of a portion being acquired for public use in any manner, including dedication, condemnation, or purchase. Lots or yards created after the effective date of this zoning ordinance shall meet the minimum requirements established herein.

      2.   Applicability To All Uses: Unless otherwise specified in this zoning ordinance, all permitted uses and all special uses shall be subject to the lot size requirements specified for a given district, unless other minimum requirements are specified for such uses elsewhere in this zoning ordinance.

      3.   Structure Built On Two Lots: A building constructed on a site consisting of two (2) lots must be located either within the required setback from the common or center lot line, or the building must be constructed on both lots.

      4.   Lots Of Record Less Than Minimum Size: Any lot of record at the time of the adoption of this zoning ordinance which contains less lot area or width than required in the district in which it is located may be used for a use in such district provided that the lot has a minimum width of thirty feet (30'). This provision shall not be construed to permit more than one dwelling unit on a lot with less lot area per family than required for the district in which such lot is located.

      5.   Use Of Lots In Single-Family Districts: In single-family districts, every building hereafter erected or structurally altered shall be located on a "lot" as herein defined, and in no case shall there be more than the principal building and the customary accessory buildings on one lot or parcel of land.

   B.   Minimum Yard Requirements:

      1.   Generally: Minimum yard requirements shall be as specified for a given zoning district. The yard requirements shall apply to all buildings and structures, as they relate to the respective lot lines, except as otherwise specifically provided in this zoning ordinance or as exempted in subsection B2 of this section.

      2.   Exemptions: The following structures shall be exempt from the minimum yard requirements set forth in this zoning ordinance: underground utility equipment, clotheslines, flagpoles, regulation mailboxes, traffic signals, fire hydrants, light poles, or any similar structure or device (see section 11-3-4 of this title).

      3.   Exceptions To Required Front Yard Setbacks: Whenever a new house is proposed on a lot on a block that was developed prior to the adoption of this title and a majority of the existing houses on the same side of the block are set back less than the minimum required front yard setback established in this title, the new house may be erected based on the established setback of the existing houses. For example, if the minimum front yard set back established by this title is twenty five feet (25'), but the majority of the houses on the same side of the block are set back twenty feet (20'), a new house may be erected based on the established twenty foot (20') setback. When there is no uniform front yard set back, but the majority of the houses on the same side of the block are set back less than the minimum established by this title, the zoning administrator shall determine the appropriate front yard setback based on the predominant or average setback on that side of the block.

   C.   Maximum Building Height: Maximum building height shall apply to all structures located in the zoning district except those structures and appurtenances excluded in section 11-3-2 of this title or special uses which have a maximum height specified in this zoning ordinance.

   D.   Access Required: No building shall be erected on any lot unless such lot abuts, or has permanent easement of access to, a public or private street. (Ord. 6734, 6-11-2003)