A sewage flow crossing borders from Tijuana, Mexico, into San Diego County is potentially causing a multi-dimensional public health emergency.

This transboundary issue, stemming from insufficient infrastructure and urbanization, presents an ongoing threat to public health with substantial socioeconomic and legal consequences.

A white paper, shared with The Hill before its public release on Tuesday, highlights the concern that this cross-border contamination introduces a mixture of chemicals and pathogens into households not only through water but also through air and soil.

Of particular alarm is the risk of the resurgence of diseases previously eliminated in California, the presence of microbes carrying antibiotic-resistant genes, and the introduction of industrial chemicals banned in the U.S., as noted by the authors, The Hill reported.

The noxious flow, a consequence of inadequate sewage treatment on the Mexican side of the border, reaches San Diego County through both ocean plumes and the Tijuana River Watershed.

This watershed traverses Baja California before re-entering its U.S. counterpart.

Recent weeks have offered a glimmer of hope for local residents as Mexico initiates the overhaul of an outdated facility that discharges millions of gallons of sewage daily into the Pacific Ocean.

However, on the U.S. side of the border, the South Bay Wastewater Treatment Plant—responsible for treating some of Tijuana’s waste under an international treaty—also falls short of fulfilling its responsibilities.

Written by B.C. Begley