The South Coast Air Quality Management District (South Coast AQMD) Governing Board has approved upgrading and expanding the monitoring and notification system that monitors for elevated levels of hydrogen sulfide (H2S) coming from the Salton Sea in the Eastern Coachella Valley.
As part of the upgrades, South Coast AQMD will develop a new, automated system that will be used to notify subscribers when H2S levels exceed the state odor nuisance standard. The California state standard for outdoor levels of hydrogen sulfide is 30 parts per billion (ppb), averaged over one hour.
Those who sign up online will receive real-time notifications via email. In addition to the upgraded public notification system, South Coast AQMD will add up to three additional H2S monitors in the area to better capture odor events. There are currently two H2S monitors in the Eastern Coachella Valley, one in Mecca, and one on the northern shore of the Salton Sea.
“Odors from the Salton Sea have long affected communities in the Coachella Valley,” said Ben J. Benoit, Chairman of the South Coast AQMD Governing Board. “Expanding the monitoring network and providing automated notifications will allow us to not only better understand odor events but provide quick and accurate information to residents.”
H2S measurements began in the Eastern Coachella Valley in 2013 to better understand and communicate odor events from the Salton Sea. In 2017, a public alert system was developed to provide notifications. Each year from 2018 to 2020, there were between 22 and 50 days where the H2S levels in the Eastern Coachella Valley exceeded the state standard. At that level, most people can smell the odor, and for some people, the odor may cause them to experience temporary symptoms such as headaches and nausea.
“I thank our communities, especially North Shore and the AB 617 committee for their commitment to ensuring this gets done,” said V. Manuel Perez, Riverside County Supervisor and South Coast AQMD Governing Board member. “I also appreciate South Coast AQMD staff for working with the community to bring clean air around the Salton Sea.”
H2S, a colorless gas that smells like rotten eggs, is formed by organic decay in the absence of oxygen at the bottom of the Salton Sea. Upwelling or mixing of the lake by regional winds can bring the H2S to the surface and into nearby communities, causing foul odors that can impact residents in the Coachella Valley. This process occurs throughout the year but is more common in the summer months.