This is an AO pursuant to the Clean Water Act issued to Placer County. The violation involves the failure of Placer County to identify significant industries contributing to its Sewer Maintenance District No.1 ( SMD-1 ) sewers which resulted in the absense of pretreatment requirements in the NPDES permit issued by the State of California Regional Water Quality Control Board for the Placer County SMD-1 wastewater treatment plant. The AO requires Placer County to develop and implement an approved pretreatment program within a year.