The boundaries between districts are, unless otherwise indicated, either the center lines of streets or alleys or such lines extended or lines parallel or perpendicular thereto. Where figures are shown on the Zoning Map between a street and a district boundary line, they indicate that the district boundary line runs parallel to the street line at a distance therefrom equivalent to the number of feet so indicated, unless otherwise indicated. Boundaries indicated as following shore line shall follow the low water shore lines, and in the event of change in shore line shall move with the actual shore line; boundaries indicated as following the center lines of streams, rivers, canals, lakes, or other bodies of water shall follow such center lines. Boundaries indicated as approximately following the city limits shall be construed as following such city limits.
(1975 Code, § 11.04, Subd. 3)