Iowa Code § 101.4: Nonconforming use.

The rules shall make reasonable provision under which facilities in service prior to the effective date of the regulations and not in strict conformity therewith may be continued in service unless the nonconformity is such as to constitute a distinct hazard to life or adjoining property; and for guidance in enforcement may delineate these types of nonconformity that should be considered distinctly hazardous, those that should not be considered distinctly hazardous and those the need for elimination of which should be evaluated in the light of local factors. As to any rule the need for compliance with which is conditioned on local factors, the rules shall provide, as a condition precedent to evaluation or issuance of a compliance order, for reasonable notice to the proprietor of the facility affected of intention to evaluate the need and of the time and place at which the proprietor may appear and offer evidence thereon.