When rain falls across San Diego, it does more than send water rushing through local rivers and creeks. It can also mobilize pollution across the watershed. New research published in Journal of Hydrology: Regional Studies (October 2026) from San Diego State University finds larger storms transport greater pollutant loads through the San Diego River watershed, offering new insight into how storm intensity, urbanization and aging sewer infrastructure can shape water quality in the region. Researchers in SDSU’s Department of Civil, Construction, and Environmental Engineering examined the San Diego River and Alvarado Creek, a small, highly urbanized tributary adjacent to SDSU that feeds into the river. … They found a statistically significant relationship between a storm’s maximum discharge, or peak flow, and the cumulative amount of pollutants transported. 

Other pollution news:

• The San Diego Union-Tribune: County, CDC to start second health survey Thursday on Tijuana River sewage crisis