The construction, maintenance, or existence within the City of any unprotected, unbarricaded, open, or dangerous excavations, holes, pits, or wells, or of any excavations, holes, or pits which constitute or are reasonably likely to constitute a danger or menace to the public health, safety or welfare, are hereby prohibited. This section shall not, however, prevent construction of excavations under a permit issued pursuant to this Ordinance or the Building Code of the City, where such excavations are properly protected and warning signs are posted in such manner as may be approved by the Administrative Official. This section shall also not apply to lakes, streams, or other natural bodies of water, or to ditches, streams, reservoirs, or other major bodies of water created or existing by authority of the State, County, City, or any other governmental agency.