"Mexico’s Laguna Region is famed as the country’s largest milk-producing area. But overexploitation of groundwater resources has combined with the effects of climate change to give the region a more dubious distinction. The remaining water supplies are contaminated with arsenic, and related rates of cancer are well above the national average."
Spanning parts of two states, Coahuila and Durango, in the north-central part of the country, the Laguna Region (known in Spanish as the Comarca Lagunera) is named after the numerous lagoons and ponds that were once found there.
But the construction of dams on the two main rivers, the Nazas and Aguanaval, in the 1950s led to the disappearance of the lagoons. The area is now largely semi-arid.
Dairy farming has taken a further toll on water resources with the planting of thirsty alfalfa crops to feed cows. A 2006 study found that milk production in Mexico required almost three-and-a-half times as much water per tonne as in the United States."