A congressional delegation from San Diego in October requested EPA support to assist the San Diego County Air Pollution District with air monitoring for neighborhoods near the Mexico border. “In early September, high levels of noxious gases such as hydrogen sulfide and hydrogen cyanide were measured by scientific teams in the river valley and noticed by residents due to the rotten egg smell even miles from the border,” reports ABC 10 News San Diego. “Ultimately, crews from San Diego County determined there was no immediate health risk, but many residents believed the crisis had reached a turning point.” … The Tijuana River sewage crisis has been an issue for decades and continues to worsen because of increasing population, a government sewage treatment facility that’s in disrepair, and strained relations with Mexico over immigration issues, according to the San Diego Coastkeeper.