The governments of Argentina, Brazil, Paraguay and Uruguay reached an unprecedented agreement this month to jointly manage—and prevent foreign control of—South America’s largest freshwater aquifer. In a document signed by their foreign ministers on Aug. 3, the four nations agreed to notify each other if they are considering “works or activities” that might have cross-border impacts on the shared, 1.2 million-square-kilometer (460,000-square-mile) Guaraní aquifer. The signing came during a meeting in San Juan, Argentina of the South American Mercosur customs union, of which Argentina, Brazil, Paraguay and Uruguay are members. The same day, the countries’ respective presidents hailed the Guaraní aquifer system as “one of the greatest freshwater reserves in the world.” That system underlies the Paraná River... [Log in to read more]