Water Quality: Trends and Challenges

The complex dynamics of the interactions between natural factors (geology, hydrology, biogeochemistry) and human factors (mining, agriculture, urban space, infrastructure) underlie a diverse range of challenges related to water quality throughout Chile. Water quality in Northern Chile is characterized by high local concentrations of dissolved salts, metals, and metalloids in surface and groundwater. Salts and metals show decreasing concentrations towards Central Chile due to higher water discharge; yet still local enrichments are observed in some tributaries (notably copper). Reservoirs and lakes in Central Chile show mesotrophic and eutrophic conditions with chronic episodes of algal blooms and fish kills from the high influx of nutrients linked mainly to diffuse pollution from agriculture and urban wastewater discharges without tertiary treatment. Water quality in Southern Chile is characterized in general by low dissolved salts concentrations and oligotrophic to oligo-mesotrophic conditions, with local exceptions in streams and bodies of water that receive industrial and treated urban wastewater discharges or that are used for fish farming. Several challenges to water policy arise when considering water quality issues: (i) integrated management approach to water quality; (ii) a more comprehensive and dense monitoring network; (iii) protection and improvement of the trophic state of Chilean lakes and reservoirs; (iv) promote the use of more sustainable treatment alternatives like enhanced natural attenuation and constructed wetlands.