Scientists at UC San Diego’s Scripps Institution of Oceanography recently launched a tool that can predict the health of water conditions five days in advance, and now a second phase will inform the public how much norovirus is in the water.
A team of researchers is working to improve the newly unveiled Pathogen Forecast Model, with plans to implement norovirus and human health forecasts in detail next summer.
The model was released in July. Its website, available in English and Spanish, aims to help families make informed decisions about when it is safe to go to the beach and swim in the ocean.
“The Pathogen Forecast Model has considerable skill in predicting five days into the future the beach water quality measurements made by San Diego County from Imperial Beach to Coronado,” said project lead Falk Feddersen about the website, which is updated daily. “Of course, just like with weather forecasts, the model has error. It is still experimental.”
According to the research team, they are in the process of performing observations of ocean currents and norovirus from the Tijuana River Estuary to Coronado.
Feddersen said they have been collaborating with Universidad Autónoma de Baja California to collect ocean current measurements. The teams began gathering samples on respective sides of the border in June 2024 and will continue through December.
According to Feddersen, norovirus, which causes gastrointestinal distress, can be contracted when swimming in sewage.
“It’s never been measured in a systematic way,” said Feddersen. “We are now measuring norovirus in a systematic way.”
The scientists are working with the county’s division of environmental health.
“They have collected water samples for us to test for norovirus,” said Feddersen, who added his team is using the county’s ddPCR Enterococcus data. “Phase two will entail a norovirus pathogen ecology module as well as perform a process called ‘data assimilation’ to improve the forecasts. Data assimilation is something that is routinely done in the weather forecasting world.”
New web dashboard
The current tool, developed with funding from the state of California, has been years in the making and follows previous studies that show how the untreated sewage flows entering the ocean at San Antonio de los Buenos travel north during summer currents.
Four sources of information feed the online dashboard’s forecast: weather forecast, offshore ocean and tide forecast, wave forecast, and river flow forecast.
In a YouTube video available on the dashboard, Feddersen says the color key — including red, yellow and green — represents the percentage of sewage at the ocean surface, indicating swimmer illness risk. The tool can be applied to the Playas de Tijuana, Imperial Beach Pier, Silver Strand and Coronado Avenida Lunar shorelines.
The colors indicate swimmer illness risk based on sewage percentage as follows:
- Red indicates high risk representing greater than 0.1% sewage
- Yellow indicates moderate risk at values between 0.001% and 0.1% sewage
- Green indicates low risk at values less than 0.001% sewage
According to Feddersen, those percentages are based on 2021 findings about human health risk monitoring of norovirus that show the value of 0.1% sewage corresponds to a 10% risk of swimmer illness and a value of 0.001% sewage corresponds to a 1% risk of swimmer illness.
“This forecast is experimental, no one has ever done anything like this before ” said Feddersen who noted the forecast has 82% accuracy. “We’re gonna get it right a good chunk of the time, but not all the time.”
The dashboard, however, is not a beach advisory or closure tool.
Official beach water quality conditions are available at http://www.sdbeachinfo.com/, as reported daily by the County of San Diego Beach & Bay Water Quality Monitoring Program.
On Aug. 20, the county and the city of San Diego began the installation of new warning signs alerting the public about the health risks from hydrogen sulfide gas in sections of the Tijuana River Valley Regional Park and Saturn Boulevard.
Earlier this year federal health survey results found that South Bay residents experience health symptoms including headaches and nausea related to the sewage crisis.
