Extreme rainfall disproportionately impacts E. coli concentrations in Texas recreational waterbodies

Waterborne pathogen contamination poses a significant threat to water resources globally and the exposure to waterborne pathogen contamination is widely recognized as unevenly distributed. Extreme weather events could exacerbate inequalities in waterborne disease as climate variability continues to escalate. However, there is a limited understanding of how extreme rainfall affects E. coli levels and whether disadvantaged communities experience disproportionate impacts from extreme rainfall on E. coli contamination. Leveraging 21 years of E. coli data along with climate data and watershed characteristics, this study employed Multiscale Geographically Weighted Regression (MGWR) models to quantify the seasonal and spatial impacts of extreme rainfall on E. coli concentrations in Texas. Our results indicate that during dry seasons, regions in northern and eastern Texas exhibit significantly higher impacts of extreme rainfall on E. coli concentrations, which is associated with high proportions of pastures, wetlands, and silt. However, during wet seasons, western and southern regions experience slightly higher extreme rainfall induced E. coli contamination risks likely due to significantly increased runoff from the rainfall together with higher slopes and clay-rich soil. In addition, we found census tracts with higher proportions of Black and Latino populations experience greater extreme rainfall impacts on E. coli levels in different months. Furthermore, an analysis of historical trends in extreme rainfall intensity indicates that climate variability could further amplify the existing inequalities in exposure to E. coli contamination. Our findings highlight the disproportionate impacts of extreme rainfall induced E. coli contamination on disadvantaged communities and emphasize the critical need for targeted intervention strategies to mitigate these risks effectively and equitably in Texas.