New tool forecasts sewage risk at San Diego beaches
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Imperial Beach has faced ongoing beach closures for years due to sewage contamination from the Tijuana River. Photo: Erik Jepsen/UC San Diego
UC San Diego scientists built a new tool that predicts the risk of sewage-contaminated water at local beaches up to five days in advance.
Why it matters: Similar to a weather forecast, families can use it to decide whether to plan a beach day, and where it will be safe to swim for the upcoming weekend.
Zoom in: The Pathogen Forecast Model, developed by Scripps Institution of Oceanography researchers, shows the sewage concentration along Coronado, Silver Strand, Imperial Beach and Playas de Tijuana shorelines.
- It uses forecasts of winds, tides, offshore currents, waves and river flow to estimate contamination levels and the risk of illness for swimmers.
- Color-coordinated indicators show the likelihood of getting sick: green is low (less than 1%), yellow is moderate (1%-10%) and red is high (10%+).
Threat level: Swimming in the bacteria-contaminated water can make people sick with norovirus — a highly contagious stomach bug that can cause vomiting, diarrhea and severe gastrointestinal problems.
Caveat: Just like with weather, "no forecast is perfect," Scripps oceanographer Falk Feddersen told Axios.
Between the lines: San Diego County currently monitors beach water quality conditions and updates daily advisories, warnings and closures.
- This model can predict those beach advisories with 82% accuracy, according to Feddersen.
State of play: This new tool, funded by the state, was created in response to the cross-border sewage crisis that's plagued San Diego for decades.
- Millions of gallons of untreated sewage from Mexico flows into the Pacific Ocean daily, forcing beach closures up the coast, harming public health and damaging the local economy.
- Scripps oceanographers have been leading the research on how polluted water travels across the border — and how to reduce it — that informs politicians and policymakers aiming to fix the issue.
What's next: Scripps researchers are currently measuring norovirus in the ocean to develop an enhanced risk assessment for swimmers for next summer.
- Congress is also considering an appropriations bill this week that would provide more funding to expand and continue operating the tool, according to UCSD.