California Code, Public Resources Code - PRC § 4601.3

(a) Any party who is aggrieved by a final order issued by the board or an administrative law judge under Section 4601.2 may obtain review of the order in the superior court in the county in which the violation occurred by filing a petition for a writ of mandate with the court within 30 days from the date of service of the order on the party.  If the aggrieved party does not petition for a writ of mandate within that 30-day period, the order of the board or an administrative law judge is not thereafter subject to review by any court.

(b) After the time for judicial review has expired, or where the party has not requested a review of the order, the administrative penalty shall be due and payable to the department within 20 days.  The department may apply to the clerk of the appropriate court in the county in which the civil penalty was imposed for a judgment to collect the penalty.  The application, which shall include a certified copy of the action by the board or the administrative law judge, constitutes a sufficient showing to warrant issuance of the judgment to collect the penalty.  The court clerk shall enter the judgment in conformity with the application.  Any judgment so entered by the court clerk shall have the same force and effect as, and is subject to the laws relating to, a judgment in a civil action, and may be enforced in the same manner as any other judgment of the court in which it is entered.