For more than three decades, the Orange County Sanitation District (OCSD) has implemented an ocean monitoring program (OMP) to evaluate potential environmental and public health effects from the discharge of treated wastewater into the submarine environment offshore Huntington and Newport Beaches, California. The OMP provides a high-quality, long-term data set used by the U.S. Environmental Protection Agency and the Regional Water Quality Control Board, Santa Ana Region for compliance review of OCDS’s National Pollution Discharge Elimination System (NPDES) permit.

The monitoring program is composed of three elements that address specific permit limits, characterize the processes that influence or are influenced by the discharge, and reveal patterns and trends over the larger geographic area of the Southern California Bight (SCB). The discharge area is located offshore of Orange County, CA within a portion of the Southern California Bight that reaches roughly from Point Conception, CA to Ensenada, Baja California, Mexico.

An example of the value of the OMP is in response to a series (1999-2001) of summer beach postings and closures in Huntington Beach due to elevated levels of surf zone bacteria. OCSD conducted an extensive series of studies to identify the source. Although it was concluded that the OCSD discharge was not the probable source, it could not be ruled out as a potential source. Therefore, OCSD began to chlorinate and dechlorinate the treated effluent as an added precaution prior to its ocean discharge. After chlorination, OCSD examined the pre- and post-chlorination data. Elevated bacterial levels persisted at the beach and the spatial and temporal patterns did not change, supporting the original conclusion that OCSD was not the source. These events highlighted scrutiny on OCSD, noted as one of the most proactive and advanced publicly owned treatment water facilities in the country.

The Woods Hole Group was contracted by OCSD as part of a world-class team to assist with: developing Strategic Process Studies (SPS); data analysis, evaluation, and interpretation; scientific review of internal and external reports and manuscripts; preparation of reports and manuscripts for interested audiences including OMP data preparation for OCSD’s website; evaluation of new and proposed legislation and regulations potentially impacting OCSD; and liaison/ review meetings. The Woods Hole Group’s involvement continues the support for OCSD’s effort to present scientifically defensible evidence to Southern California Bight stakeholders.