(2) In any ordinance adopted under subsection (1) of this section, a city shall not be authorized to:
(a) Levy assessments in an economic improvement district in any year that exceed one percent of the real market value of all the real property located within the district.
(b) Include within an economic improvement district any area of the city that is not zoned for commercial or industrial use.
(c) Levy assessments on residential real property or any portion of a structure used for residential purposes. [1985 c.576 §2; 1989 c.1018 §3; 1991 c.459 §350; 1991 c.902 §5]