Upon the declaration of a water supply emergency as provided in § 15-603, the Mayor is authorized to call on all water consumers to employ voluntary water conservation measures to limit or eliminate non-essential water uses including, but not limited to, limitations on the following uses:
   (a)   Sprinkling of water on lawns, shrubs or trees (including golf courses);
   (b)   Washing of automobiles;
   (c)   Use of water in swimming pools, fountains and evaporative air conditioning systems; and
   (d)   Waste of water.