The board, its employes [employees] and the appraisers hereinafter provided for and their assistants, may enter upon lands within or without the district in order to make surveys and examinations to accomplish the necessary preliminary purposes of the district, or to have access to the work; being liable, however, for actual damage done; but no unnecessary damage shall be done. Any person or corporation preventing such entry shall be guilty of misdemeanor, punishable by fine not exceeding fifty ($50.00) dollars.