Water Quality and Pollution
Information on the water quality of Mexico's rivers published by the National Water Commission is limited to only two parameters, Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). No other water quality indicators are used to classify water bodies and no water quality data using other pollutants as parameters are readily available.
Surface water bodies in Mexico are classified in five different ambient water quality classes, using BOD and COD as indicators. In 2005 surface water quality was measured in 509 sites using these parameters.
Using BOD as an indicator, in 2005 5% of water bodies were classified as highly contaminated (BOC > 120 mg/l) and 10% as contaminated.(BOD > 30 mg/l). If COD is used as an indicator, the respective shares increase to 12% for highly contaminated (COD > 200) and 26% for contaminated (COD > 40) waterbodies.
The highest levels of contamination are found in the hydrological regions of the Northeast, Balsas, Mexico Valley and Lerma-Chapala.
Read more about this topic: Water Resources In Mexico
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