Any records, reports, or information obtained under this chapter shall be available to the public; except that upon a showing satisfactory to the department by any person that records, reports or information, or a particular part thereof to which the department has access under this section if made public, would divulge production or sales figures or methods, processes or production unique to such person or would otherwise tend to affect adversely the competitive position of such person by revealing trade secrets, the department shall consider such record, report, or information or particular portion thereof, confidential. Nothing in this section shall be construed to prevent disclosures of such report, record, or information to federal or state representatives as necessary for purposes of administration of any federal or state laws or when relevant to proceedings under this chapter. Information concerning the presence or concentration of substances in waters shall not be considered confidential by the department.