- Amid a water crisis, Yaqui communities in the northwestern Mexican state of Sonora lack safe drinking water due to contamination by arsenic, salinity and heavy metals as unveiled by several studies over the years.
- The water crisis, driven by decades of overexploitation, unequal water distribution and drought, intensifies contamination, particularly affecting coastal areas with saltwater intrusion and surpassing safe limits in certain regions.
- Members of the Yaqui tribe blame mining operations and agribusiness for the contamination, but there are few studies to confirm their source.
- They argue contamination has led to diabetes and health complications among community members, as well as cultural impacts.
YAQUI VALLEY, Mexico — In June, residents of communities along the Yaqui River found various dead tilapia, carp and catfish floating on the banks of the river. According to Guadalupe Flores Maldonado, this was not a singular event. Fish die-offs have been happening for over a month now.
Health officials said it was because of the heat, said Maldondo, a local from the Yaqui village of Loma de Bácum. “However, the heat has always been like this here, and there has never been a fish die-off. That makes us suspect that there is contamination.”
For generations, the waters of the Yaqui River ran so clean that the Yaqui peoples could fish from its banks and drink safely from the stream. But in recent decades, a large portion of the river has dried up and the little water that remains is contaminated. Locals point to a host of unresolved problems, including overexploitation, dams and aqueducts diverting water, drought, mining waste, agrochemical abuse and poor waste management.
Few scientific studies that analyze this contamination, its sources and its impact on locals exist, leaving a gap in assessing this environmental problem. Locals whom Mongabay spoke with say they feel left behind by the government and health officials.
Maldonado first noticed a change in the quality of water in 2016, when several large companies began mining operations in the upper course of the Yaqui River. Over the years, arsenic contamination produced by these companies has leached into the water, leading to health complications and other impacts in Yaqui villages downstream, he said.
“In recent times, there have been more deaths from cancer but both the Ministry of Health and the Federal Commission for Protection against Health Risks say it is due to other causes,” Maldonado told Mongabay over WhatsApp audio messages. “We are trying to get all the mining companies that are bordering our territory to go farther away because their toxic waste goes into the subsoil and that contaminates us.”
But overall water problems in the Yaqui Valley came way before the mining companies. Ever since the mid-20th century when the Mexican government began developing the Yaqui River dam system, which is an extensive arrangement of imposing concrete dams that stopped the river’s flow, the Yaquis have been largely left without water. In addition, locals complain that intensive agricultural producers who use large quantities of fertilizers have affected the little water that is left.
Tracking sources of contamination
There are no mining projects inside the Yaqui tribe’s territory. However, in the upper course of the Yaqui River, many kinds of minerals are mined along the river by transnational companies, including gold, silver, copper and lithium. Operations are carried out by the Canadian mining companies Pan American Silver and Kootenay Silver Inc., as well as several national companies.
Mongabay found no evidence that suggests these companies are directly responsible for the contamination in the Yaqui territory.
“In the middle basin of the Yaqui River, contamination has been associated with mining activity,” particularly mercury contamination, Martín Enrique Jara Marini, senior researcher at the Food and Development Research Center (CIAD), told Mongabay. In the lower basin where the Yaqui territory is located, the contamination is because of the large amounts of agrochemicals used, he said. “However, more precise studies are required to determine if this is really true.”
Although the Yaqui Valley is a semidesert, it’s considered one of the country’s most productive breadbaskets. Research has shown that intensive agricultural production contributes to poor water quality in the area because the large quantities of fertilizers applied, such as phosphorus, leach into water sources.
“These are places of very intensive agriculture where crops are grown several times a year in several agricultural cycles,” Maria Vicenta Esteller, a researcher at the Inter-American Institute of Technology and Water Sciences at the Autonomous University of Mexico State, told Mongabay. “The typical crop in the Yaqui Valley is wheat, so almost all of the companies have wheat crops, and when it isn’t the wheat season, they grow chile peppers and vegetables as well as a few fruit trees.”
One study found that, although minimal, the levels of phosphorus in the lower basin of the Yaqui River exceeded the recommended values for the protection of aquatic life. Too much phosphorus can stimulate the excess growth of algae, which leads to low dissolved oxygen levels, a blockage of sunlight needed by organisms and plants in the water and a degraded habitat for macroinvertebrates and other aquatic life.
Near the coast, shrimp farms dump waste into the Guasimas Bay, where the Yaqui River once poured into the Gulf of California. The contamination is made up of organic waste, chemicals that are added to the shrimp’s food and antibiotics. Mario Luna Romero, a spokesperson from the Yaqui community, said the shrimp farms have become a problem because they release contamination in the bay. In the past, Yaquis could fish and collect clams and put them straight on a plate. Now, the shells come out dirty because of all the pollution.
“It is true that [shrimp farms] are a problem because they use a lot of water, which is recirculated,” Vicenta explained. “[They] take water from the bay, put it in the farms, and a large volume of water from the shrimp farms is dumped back into the sea or, in this case, the bay.”
Impact on Yaqui community
According to José Moctezuma from the National Institute of Anthropology and History, due to the lack of water and contamination, the Yaquis have been unable to cultivate culturally important foods, such as wheat, corn and beans. This has led to a dependency on junk food, which has caused high rates of diabetes and other health issues among Yaqui peoples.
“A series of foods, both animals and vegetables, are disappearing or becoming contaminated in such a way that no one grows anything anymore,” he told Mongabay over a video call.
For the Yaquis, the river represents much more than production and profits; its decline threatens the survival of certain elements of Yaqui culture. “It has always been a connection with the spiritual,” Luna told Mongabay. “Water, due to its ability to evaporate, could then be a conduit to communicate with the gods or with your loved ones who died.”
In one study, researchers assessed the drinking water in three Yaqui villages — Vícam, Potam and Cócorit — and found high levels of arsenic, which is naturally occurring but can also be released into the environment through human activities, such as mining and agriculture. It is number one on the priority list of hazardous substances issued by the U.S. Agency for Toxic Substances and Disease Registry (ATSDR).
According to the researchers, Potam showed the highest concentration of arsenic, exceeding both Mexican and international standards. Vícam and Cócorit were within the national standards, but both exceeded the international limit.
Exposure to arsenic is linked to a variety of cancers in humans, as well as diabetes, cardiovascular diseases, kidney and liver problems and other health complications. Other studies from 2019, 2018, 2013 and earlier showed similar results.
“The main impact [of contamination] is environmental — with pollution, aquatic fauna and flora are lost, along with the ecosystem services the river provides,” Briseida Lopez Alvarez, a researcher at the College of San Luis, told Mongabay. “Likewise, water cannot be used for the population without treatment, nor for recreational or cultural activities. This last aspect is vital for the Yaqui peoples.”
Banner image: A traditional Yaqui ceremonial hut in Vícam which is made from alamo — a tree threatened by the lack of water in the region — mesquite (Prosopis) and giant reed (Arundo donax). Image by Abimael Ochoa Hernández for Mongabay.
As drought parches Mexico, a Yaqui water defender fights for a sacred river
Citations:
Almazán, B.R., Esteller, M.V., Garrido-Hoyos, S.E. et al. (2023) Nitrogen and phosphorus budget in an intensive irrigation area and effects on littoral water and groundwater (Yaqui Valley, Northwestern Mexico). Environ Monitoring Assessment, 195, 147. doi:10.1007/s10661-022-10721-5
Vega-Millán, C.B., Dévora-Figueroa, A.G., Burgess, J.L. et al. (2021). Inflammation biomarkers associated with arsenic exposure by drinking water and respiratory outcomes in indigenous children from three Yaqui villages in southern Sonora, México. Environmental Science Pollution Research, 28, 34355–34366. doi:10.1007/s11356-021-13070-x
García-Rico, L., Meza-Figueroa, D., Jay Gandolfi, A. et al. (2019). Health Risk Assessment and Urinary Excretion of Children Exposed to Arsenic through Drinking Water and Soils in Sonora, Mexico. Biological Trace Element Research, 187, 9–21. doi:10.1007/s12011-018-1347-5
Maldonado Escalante, J. F., Meza Figueroa, D., Dévora Figueroa, A. G., García Rico, L., Burgess, J. L., Lantz, R. C., … Meza Montenegro, M. M. (2018). An integrated health risk assessment of indigenous children exposed to arsenic in Sonora, Mexico. Human and Ecological Risk Assessment: An International Journal, 25(3), 706–721. doi:10.1080/10807039.2018.1449098
Burgess, J., Kurzius-Spencer, M., O’Rourke, M. et al. (2013). Environmental arsenic exposure and serum matrix metalloproteinase-9. Journal of Exposure Science & Environmental Epidemiology, 23, 163–169. doi:10.1038/jes.2012.107
Meza-Montenegro, M. M., Jay Gandolfi, A., Santana-Alcántar, M. E., et al. (2012). Metals in residential soils and cumulative risk assessment in Yaqui and Mayo agricultural valleys, northern Mexico. Science of the Total Environment, 433: 472-481. doi:10.1016/j.scitotenv.2012.06.083
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