Real-Time Empirical Risk Assessment From Recurrent Coastal Sewage Plumes

Area of Science:

• Environmental Science
• Oceanography
• Public Health

Background:

• Untreated wastewater discharge from Mexico poses significant human health risks to coastal communities in the San Diego-Tijuana border region.
• Understanding the spatial and temporal dynamics of wastewater plumes is crucial for effective risk management.

Purpose of the Study:

• To develop and validate a risk assessment tool for coastal communities to predict wastewater exposure.
• To link environmental parameters (temperature, salinity) to wastewater concentration and associated health risks.

Main Methods:

• Utilized hindcast oceanographic simulations (2017-2019) to model wastewater plume behavior.
• Calculated exposure timescales (duration, return time) for popular beaches.
• Developed statistical models correlating environmental anomalies with wastewater concentration and illness risk.

Main Results:

• High wastewater exposure events occurred monthly at southern beaches, lasting less than a week, and less frequently further north.
• Lower salinity and temperature anomalies were strongly associated with high wastewater concentrations.
• Statistical models incorporating salinity and temperature anomalies effectively predicted wastewater-associated illness risk (R² = 0.63-0.78).

Conclusions:

• The developed risk assessment tool efficiently links environmental data to wastewater pollution.
• This approach provides a practical method for coastal communities to manage health risks from wastewater contamination.
• The tool has potential applications for other coastal areas impacted by pollution.