"Damage to soils resulting from cultivation and elimination of the natural vegetation is widely reported in reference to the environmental impacts of illicit drug cultivation, as are the likely effects of the discharge of the chemical wastes from coca processing to soils and waterways. However, very little field assessment on the quantity of discharges and their effects on the environment (soils, fauna, flora or water) has been carried out by government agencies or universities. The only analysis found by this study was conducted in Chapare (Bolivia) in 1992 (Southwest Research Associates, 1993, quoted by Henkel, 1995). Here, a study of three cocaineprocessing laboratories found that pollution was concentrated in a small area at the processing site. Most chemicals were disposed of in holding ponds constructed for the purpose and were not dumped into nearby streams. Chemical spills at the site were quickly diluted by the high rainfall received in the region. Because coca processing sites are widely scattered in the Chapare, pollution is widely dispersed rather than concentrated at a few large sites. Some loss of soil microorganisms was noted, but no damage to wildlife, vegetation, fish species or bird life was detected near the processing laboratories. However, the study did not assess the long-term effects of pollution.
"For Colombia, DNE (2002) states that the agrochemicals used in coca processing are capable of polluting freshwater sources for human consumption, but no specific cases of this are given."

Source

United Nations Office on Drugs and Crime, "Coca Cultivation in the Andean Region: A Survey of Bolivia, Colombia and Peru" (Vienna, Austria: June 2006), p. 31.
http://www.unodc.org/pdf/ande…