Early trunk sewers were built in Orange County as early as 1912. In 1920’s first ocean outfall and screening plant at the present location of Plant 1 were constructed. 1950 wastewater reclamation system was built and effluent from primary treatment at Plant 1 was discharged to bean fields for irrigation. 1954 Plant 2 was constructed located near the ocean and adjoining the Santa Ana River.  Second ocean outfall was constructed.

Most of the effluent is discharged five miles into the Pacific Ocean in 190 feet of water.  Plant 1 and 2 currently have activated sludge treatment, digester and sludge processing, and trunk sewer lines.  The system of sewage collection, treatment, and disposal is considered one of the most modern and advanced in the nation.Over 2.1 million people served.  Over 470 square miles.  825 miles of trunk lines.  Two treatment plants.  270 million gallons of wastewater per day.

The Orange County Sanitation District was designated as an Orange County Historical Civil Engineering Landmark in 1994.   There are plaques, one is located at Plant No. 1, Fountain Valley, CA and the other is located at Plant No. 2, Huntington Beach, CA.