The zoning districts enumerated in this Part 1 are hereby established for the County.
Zoning districts established by this Part 1 are bounded and defined as designated on the Official Zoning Maps and subsequent modifications thereto. Said Zoning Maps, properly attested, and maps indicating the effects of zoning cases conducted hereunder shall be and remain on file in the office of the Director of Planning and in the office of the Clerk of the Circuit Court of the County. The Director of Planning shall maintain maps showing the result of any zoning case approved pursuant to this Part 1.
The following rules shall be used to determine the precise location of any zoning district boundary:
A. 
Boundaries shown as following or approximately following the limits of any municipal corporation shall be construed as following such limits.
B. 
Boundaries shown as following or approximately following streets shall be construed to follow the center lines of such streets.
C. 
Boundaries shown as following or approximately following platted lot lines or other property lines as shown on the Tax Maps shall be construed as following such lines.
D. 
Boundaries shown as following or approximately following railroad lines shall be construed to lie midway between the main tracks of such railroad lines.
E. 
Boundaries shown as following or approximately following shorelines of any water body shall be construed to follow the mean high-water lines of such water body and, in the event of change in the mean high-water line, shall be construed as moving with the actual mean high-water line.
F. 
Boundaries shown as following or approximately following the center lines of streams, rivers or other continuously flowing watercourses shall be construed as following the channel center line of such watercourses taken at mean low water, and, in the event of a natural change in the location of such streams, rivers or other watercourses, the boundaries shall be construed as moving with the channel center line.
G. 
Boundaries shown as separated from and parallel or approximately parallel to any of the features listed in Subsections A through F above shall be construed to be parallel to such features and at such distances therefrom as are shown on the Map.
H. 
Boundaries shown as following or approximately following the edges of watersheds as identified by the U.S. Natural Resource Conservation Services shall be construed as following such edges of the watershed.
I. 
Whenever any road, alley or other public way is vacated by official action as provided by law, the zoning districts adjoining the side of such right-of-way shall be automatically extended, depending on the side or sides to which such lands revert, to include the right-of-way of the public way thus vacated, which shall thenceforth be subject to all regulations of the extended district.