Treated municipal wastewater is discharged to the Pacific Ocean through a 4,400 foot outfall/diffuser system as regulated by the California Regional Water Quality Control Board – NPDES Permit No. CA 0048003. The outfall terminates in approximately 55 feet of water. The design of the outfall is intended to diffuse the treated municipal waste prior to discharge, creating a minimum initial dilution of 165 parts seawater to 1 part treated municipal waste at the point of release.
This line also serves to convey treated wastewater from the City of Pismo Beach which shares this line by means of a connection at the District’s treatment plant site. Discharge of treated municipal waste from Pismo Beach is regulated under California Regional Water Quality Control Board – NPDES Permit No. CA0048151.
The outfall pipe/diffuser system is inspected tri-annually to ensure proper operation and structural integrity of the system. The inspection is conducted from the shoreline to its ocean terminus and includes general observations and photographic records of the outfall/diffuser as well as that of the ocean bottom in the vicinity of the system.