old tires and trash in the Tijuana River channel

Tijuana River Research

Metagenomic analysis and non-targeted chemical analysis of transborder water flows in the Tijuana River watershed

(PI Kari Sant, Co-Is Scott Kelley and Eunha Hoh)

Transborder water flows at the US-Mexico border frequently occur during major storm events and when pump station failures occur carrying waste to water treatment facilities. As such, the Tijuana River is a significantly impaired watershed in the US, resulting in Imperial Beach closures for more than half of each calendar year. In this study, we use two modern methods (shotgun metagenomic sequencing of surface water DNA, and non-targeted mass spectrometry) to examine the microbiological and chemical constituents of these transborder flows at key sites and a downriver estuarine site. 

Read journal articles about the research: International Journal of Environmental Research and Public Health and Environmental Pollution.


Real-time water quality monitoring

(PI Trent Biggs, co-PI Natalie Mladenov)

Cross-border flows along the Tijuana River transport a combination of treated and untreated wastewater, stormwater, industrial pollution, sediment, and trash. This impaired water quality threatens human health and ecosystems, including the Tijuana River Estuary and coastal zones and beaches downstream. Therefore, there is an urgent need for real-time water quality monitoring in the Tijuana River and early warning systems of coastal contamination. This project employs a multi-sensor approach for monitoring water quality parameters in the Tijuana River at the US-Mexico border and in the Tijuana River Estuary. Our team is testing and ground-truthing fluorescence-based sensors that track the optical fingerprints of sewage and turbidity sensors for monitoring sediment loads. Outputs of this study will inform future binational efforts to monitor cross-border pollution in the Tijuana River.

Find out more about this project.


Surveillance of SARS-CoV-2 in the Tijuana River

(PI Natalie Mladenov, co-PIs Matthew Verbyla and Kari Sant)

In communities where many people lack sewer connections, sewage-laden streams may serve as sites of wastewater surveillance to provide critical information on community infection rates. In this research project, MS student Alma Rocha evaluated the presence and persistence of the novel coronavirus in wastewater and in the Tijuana River and Tijuana River Estuary. Using qPCR and digital droplet PCR to quantify coronavirus and other markers of fecal contamination, Alma found 1) high concentrations of SARS-CoV-2 RNA in the Tijuana River during the pandemic, but not in the estuary, and 2) that normalized coronavirus loadings could be used to predict increases in COVID-19 cases in Tijuana.

Learn more about this research.

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