A structure or the use of a structure or premises which was lawful before the passage or amendment of this chapter, but which is not in conformity with the provisions of this chapter, may be continued subject to the following conditions:
1. If such use is discontinued for six consecutive months, any future use of the structure or land shall conform to this chapter.
2. Uses or adjuncts thereof that are or become nuisances shall not be entitled to continue as nonconforming uses.
3. If any nonconforming use or structure is destroyed by any means, including flood, it shall not be reconstructed if the cost is more than 50 percent of the market value of the structure before the damage occurred, unless it is reconstructed in conformity with the provisions of this chapter.
Except as provided in subsection 2 of this section, any use which has been permitted as a conditional use or variance shall be considered a conforming use.