and the methods used to extract it. Gold mining activities require high volumes of water to obtain the metal and this leads to an alteration in surface and underground water bodies. Rivers are affected as many local mines discharge untreated waters and tailings directly to waterways. When rivers like Magdalena and Cauca reach Antioquia, they receive polluted loads caused by mining activity from tributaries from the Northeast and Bajo Cauca regions. In addition to the local mines, informal mining operations add to the water pollution by directly discharging many pollutants like suspended sediment, organic matter, acid drainage, metals, grease, oils and fuels into the waterways. The major health risk from artisanal mining is mercury exposure. Among the emissions from artisanal mining, two thirds are released locally into soil and water near mining operations, and a third is released into the atmosphere, where it can potentially attack people far from mining sites too. Artisanal mining is the largest single source of atmospheric mercury. Pollution due to Mercury can occur in two ways- a) through Air and b) through Water. Mercury vapors in the air around amalgam burning sites can be alarmingly high and almost always exceed the WHO limit for public exposure of 1,000 nanogram/cubic meter. This risks the health of workers but also those in the communities surrounding the processing centers. Exposure to levels of mercury vapors above 1,200,000 nanogram/cubic meter can be fatal. Water pollution due to mercury has become one of the biggest concerns in recent years. Artisanal and small-scale gold miners use mercury to extract gold in developing nations worldwide, contributing an estimated 30% of global mercury emissions annually. Colombia is the world's highest per capita mercury polluter. The total mercury release/emissions to the Colombian environment can be as high as 150 tons/a. In the case of Antioquia, the total amount of mercury used in the Northeast and Bajo Cauca regions is around 93.4 tons/annum. Water pollution due to mercury contamination Studies conducted in the Department of Cordoba showed that mercury levels in fish species in the basin of San Jorge river exceed the specified threshold (200 ng/g) for populations at risk established by World Health Organization. Few other studies show mercury contamination in plants, fish and sediments in some water bodies in the region of Mojana. In the region of Ayapel, significant concentrations of mercury in water, plants, fish and sediments swamp was found. Sources suggest