In 2023, Alianza CV also mounted a hydrogen sulfide monitor on a platform above the sea on the north side to track production of the gas. Based on their results, researchers say the state monitoring isn’t sufficient.
Between January and August 2024, the Alianza hydrogen sulfide (H2S) monitor, mounted directly above the Salton Sea on the northern side, found 214 incidents in which H2S exceeded the 30 ppb threshold set by the California Air Resources Board compared to only 42 such events documented by the South Coast Air Quality Management District monitor on Torres Martinez land to the northwest. (Source: Diego Centeno)
Data from the monitor differs from a hydrogen sulfide monitor run by the South Coast Air Quality Management District (SC AQMD). “Since January, our sensor has detected 200 hydrogen sulfide exceedances; the SC AQMD sensor detected only 40,” says Diego Centeno, a doctoral student working with Arzeno-Soltero at UCLA, who grew up around the Salton Sea. The California Air Resources Board established the one-hour hydrogen sulfide standard at 30 parts per billion; anything beyond that is deemed an exceedance. The discrepancy, they believe, is due to the fact that the SC AQMD monitor sits on land northwest of the sea, and the exceedances the Alianza monitor detects typically occur when the winds come from the north.
Arzeno-Soltero says accurate exceedance data is crucial for public health protections. Even chronic hydrogen sulfide exposures below the level authorities consider dangerous have been associated with an increased prevalence of neurological effects, including headaches, mood disorders, and depression, according to a 2023 study.
There’s even less monitoring for HABs, which can produce cyanotoxins that can cause headaches, sore throats, nausea, vomiting, and other symptoms. A pilot study conducted between September 2020 to August 2021 found at least twelve genera of cyanobacteria were detected in the nearshore Salton Sea, and at least one animal was reported dead from ingesting toxins. Despite the report’s conclusion that the algal blooms presented “a significant health risk” from toxins, there is minimal monitoring at the state level. “Due to funding, recent Harmful Algal Bloom monitoring has only occurred before holidays when people may be recreating on the sea,” stated an email response from the CWB.
“Currently, there are no federal or state regulatory standards for cyanotoxins in recreational waters,” said the email reply. Participating state agencies have developed voluntary guidance for responding to HABs in recreational waters. The guidance suggests that if field screening determines cyanobacteria or cyanotoxins are present, responding organizations should collect water, scum or algal mat samples for laboratory analysis; if HABs or toxins meet or exceed trigger levels, the responding organization should report to the HABs hotline and post an advisory sign.
UCLA graduate student Cruz Marquez checks the mooring for the Alianza water quality monitor in the Salton Sea. (Photo credit: Alejandra Lopez)
Roxana Chavez, a regional organizer for a women’s farmworker leadership organization, Alianza Nacional de Campesinas, Inc, says the Imperial County Division of Public Health put up a billboard in early October near her home in Desert Shores, a community on the northwest shore of the Salton Sea. The billboard explains: “In certain conditions, the water may produce toxic Harmful Algal Blooms (HABs), in which children and pets are most susceptible to illness from water contact and/or ingestion”. It also offers a QR code that it says will be updated to reflect current water quality as yellow, orange, or red, corresponding to caution, warming, or danger, respectively. But they’ve done little else to inform the community about HABs. “We notice the smell but also the color when the water changes—it becomes more greenish,” Chavez says.
Jasmyn Phillips lives in Calipatria, on the sea’s southern end. Beyond billboards, she wants to see more effort to educate Salton Sea communities about HABs—and more consistent water quality monitoring, since the Salton Sea is such a dynamic ecosystem. “Just because there are algal blooms doesn’t necessarily mean they are producing toxins,” she says.
Looking to Nature-based Solutions
While excess nutrients fuel the conditions that cause microbes to produce hydrogen sulfide and LPS, reducing nutrient runoff enough to make a significant difference is not likely a viable solution in the near-term because the levels are so high.
The “LPS in sea spray” hypothesis is an intriguing one that needs further research—but it’s not clear how the story ends, says Cohen. “Even if you stopped nutrient inputs immediately,” he says, “you would not see immediate benefits, and you might not see benefits for decades, because there’s too much nutrient cycling within the Salton Sea.”
Community members, including Eric Reyes, executive director of Los Amigos de la Comunidad, a nonprofit organization that aids underserved communities facing environmental injustices in Imperial County, say the lack of engagement from policymakers as well as the agricultural community is wearisome. “We have a sense of urgency that we don’t see anyone else expressing,” says Reyes.
Palomino rejects the notion that nothing can be done to soak up nutrients. “How do we preserve wetlands or construct more, so they are a nature-based solution?” she asks.
