Pozo

With nearly groundwater supplying nearly 40% of the city’s drinking water, the implementation and maintenance of extraction wells is critical to water security. As of 2013, 1,965 wells pumped 57 m3 /s from the local aquifer, a number that may increase with an increasing population and reliance on groundwater. This high rate of extraction is calculated to be causing approximately 30m3/s of overdraft, exploiting the aquifer at an alarming rate. Although the city has implemented and continues to work on artificial recharge projects, some of these spaces which often need to be left open for water percolation are subjected to dumping or urbanization.

Extraction paired with differential subsidence, further reinforces a cycle of supply from a finite source with a force that disrupts stable ground, “lead[ing] to faults in water mains, sewers, oil pipelines and tanks..For water leaks, losses are around 37-40%, resulting in a total water loss of 23 m3/s (525 MGD). This represents a cost of 56 million USD at the lowest water tariff in the city for municipal water (1peso/m3 or 0.08 USD/m3).” Overexploitation of the aquifer through pumping also exposes it to further pollution, as Jimenez further notes “TSS content has increased from 1,000 mg/L to 20,000 mg/L, the sodium content from 50-100 mg/L to 600-800 mg/L, the ammoniacal nitrogen content from 0-0.03 mg/L to 6-9 mg/L, and the iron content from < 0.1 mg/L to 3-6 mg/L.”

The inability to distinguish the sometimes devastating effects of subsidence on parts of the city already affected by damage from earthquakes and institutionalized poverty is another key issue at play in Mexico City politics. Groundwater wells were historically shifted from the center of the city as subsidence destabilized the cathedral, but relocated wells were instated not only in places with the right geological conditions, but in some areas where urbanization was quickly taking hold, particularly in the district of Iztapalapa. Today Iztapalapa is the most densely-populated borough of Mexico City and one considered to be the most dangerous due to its high crime-rate and drug trafficking. These conditions have suspended many of its residents, thousands of whom have moved from rural parts of the country in search of work, within an environment of violence where water extraction can be used to politically position the district. Often depicted as a technological advancement capable of resolving the water crisis, the new deep wells in Iztapalapa may actually be responsible for further destabilizing ground.