High heat and untreated wastewater flows from Mexico in the Tijuana River Valley have led to elevated hydrogen sulfide emissions in South Bay. The San Diego Air Pollution Control District's network of monitors are tracking these emissions. The county may also be contributing to a broken pump in Tijuana's sewage infrastructure. The US International Boundary and Water Commission reported a pump failure at Mexican Pump Station PB1 causing transboundary flows at Stewart’s Drain. While such incidents tend to rise during heat events, the Tij River Valley experiences dry-weather flows of untreated wastewater. The highest readings were found in an inland area in the Nestor neighborhood. The public can take steps to reduce the odor by limiting outdoor activities, keeping doors and windows closed, increasing air circulation indoors using fans or air conditioning on recirculation mode, and keeping rescue medication(s) readily available.