The county health officer may upon reasonable cause to believe that fly or odor nuisance, or rodent infestation exists, investigate conditions productive of flies, fly larvae, pupae, rodents or odor. He shall have the power while in the performance of his duty to enter upon any premises to discover, or to inspect any thing or condition which is productive or susceptible to the production of flies, unreasonable odors or rodents. A copy of the inspection report shall be given to any registrant. If he determines that a fly nuisance, production of unreasonable odor, or rodent infestation exists he may issue a written order requiring abatement. (Prior gen. code § 3-97.3)