In the communities surrounding the Endhó Dam in Hidalgo State, Mexico, residents are confronting a public health crisis they attribute to decades of environmental contamination linked to industrial and urban wastewater. Local activists report a disturbingly high incidence of cancer cases clustered within neighborhoods near the dam, which has become a symbol of environmental neglect.

Yury Uribe, a former seamstress and current community activist in General Pedro María Anaya, recounted the toll in her neighborhood, identifying dozens of residents who have died from various cancers. She pointed to more than 40 cancer-related deaths, 15 survivors, and six current cases within a few blocks—figures she describes as incomplete yet indicative of the scale of suffering. “It’s not normal to have this many sick people in a community,” she said.

The roots of the crisis date back to the 1970s, when federal authorities redirected Mexico City's storm runoff and untreated wastewater into the region. This policy effectively turned the area into a disposal site for the byproducts of a metropolis exceeding 20 million inhabitants. Compounding the problem is the presence of a heavy industrial corridor containing more than 100 factories and an oil refinery, many of which discharge untreated effluents into the Tula River. The river’s contaminated waters subsequently flow into the Endhó reservoir, turning it into what residents call a massive cesspool.

Environmental experts and human rights officials have classified the Endhó basin as one of Mexico's most persistent “sacrifice zones”—areas where local health and ecosystems are compromised for the economic benefit of a larger population. The United Nations special rapporteur on toxics and human rights has highlighted the region as emblematic of such zones, where environmental degradation and public health impacts are disproportionately borne by marginalized communities. Similar patterns of environmental sacrifice have been documented worldwide, including in the United States' "Cancer Alley," Italy’s steel production regions, and Canada’s oil sands operations.

Locals describe the environmental conditions as dire. The air is often thick with sulfurous odors, while chemical foam frequently floats across homes and roads. Water pollution has fueled rampant aquatic weed growth, contributing to a persistent ecosystem imbalance. Magnolia Sánchez, a resident of San Mateo La Curva, described daily life in the area as "hell," adding that her cousin died of breast cancer, another loss attributed to the toxic environment.

Longtime residents recall when the contamination first appeared. Feliza Camacho, who was newly married in 1972, observed the transformation of the reservoir’s clear waters into a murky and foul-smelling body, marking the start of decades of environmental and health challenges for the area.

Despite the visible impacts, efforts to address the contamination and its health consequences have been slow. Residents continue to demand greater attention and remediation, underscoring the ongoing struggle between industrial development, urban needs, and the protection of vulnerable communities’ health and environment.