Heavy Rains Near Lisbon Trigger Sewage Overflow

An aging combined sewer system in the suburbs of Lisbon, Portugal, experienced a sewage overflow due to heavy rainfall. Untreated domestic sewage, containing nutrients and fecal contaminants, was discharged directly into the Tagus River estuary and spread into the coastal waters. Large amounts of nitrogen and phosphorus nutrients have entered the estuary’s slow-flowing areas; combined with current favorable water temperature conditions, this increases the likelihood of harmful algal blooms. At the same time, the pathogenic microorganisms carried by the sewage pose health risks to coastal bathing areas.