(a) The division shall have the right to direct and conduct such investigations as it may reasonably deem necessary to carry out its duties as prescribed in this part. For this purpose, the employees of the division or any authorized representatives shall have the right to enter at reasonable times on any property, public or private, for the purpose of investigating the condition, construction, or operation of any dam or other artificial barrier dealt with in this part. Such employees or representatives shall also have the right to require written statements or the filing of reports with respect to pertinent questions relating to the construction or operation of any dam; provided, however, that no person shall be required to disclose any secret formula, processes, or methods used in any manufacturing operation or any confidential information concerning business activities carried on by him or under his supervision.

(b) It shall be unlawful for any person to refuse entry or access to any authorized representative of the division who requests entry for purposes of inspection and who presents appropriate credentials. It shall also be unlawful to obstruct, hamper, or interfere with any such representative while in the process of carrying out his official duties.