Hydrogeology of a contaminated sole-source karst aquifer, Mérida, Yucatán, Mexico

The City of Merida, in the State of Yucatán, obtains its drinking water primarily from three well fields located in the periphery of the city. In addition, there are water supply wells within the city. Water from the public water supply contains lead, cadmium, chromium in excess of the Mexican Drinking Water Norm. The following organic contaminants have also been identified in the ground water in the southern portion of the city: TCA, PCE, TCE, and carbon tetrachloride (CTET). Mérida currently obtains about 65 % of its drinking water supply from the JAPAY-1 well field which draws water from the southeastern section of the city, where most of Merida’s industrial activity is concentrated. No information is available on the water quality from this well field, but it is likely to be also heavily contaminated. A ground water monitoring scheme is suggested. A hydrogeological reserve zone should be established to allow the inhabitants to have a sustainable source of drinking water.