California Code, Government Code - GOV § 11515

In reaching a decision official notice may be taken, either before or after submission of the case for decision, of any generally accepted technical or scientific matter within the agency's special field, and of any fact which may be judicially noticed by the courts of this State. Parties present at the hearing shall be informed of the matters to be noticed, and those matters shall be noted in the record, referred to therein, or appended thereto. Any such party shall be given a reasonable opportunity on request to refute the officially noticed matters by evidence or by written or oral presentation of authority, the manner of such refutation to be determined by the agency.