2000 are only one indicator that market forces are at play in determining what activities are high-value and those that are not. Water tariffs that are charged by utilities to treat and supply water to residential and commercial users have to be clearly distinguished from the pricing of water resources. See:Water tariffs in Chile Water resource base Surface and groundwater resources Chile is characterized by irregular distribution of rainfall totals among three distinct climate regions: the Atacama Desert in the northern region, the temperate and Mediterranean central region, and the cold and rainy southern region. The dry Atacama Desert region receives an average of 44.5 mm of precipitation annually while the southern regions receive 3000 mm of annual precipitation on average. According to FAO, average annual precipitation is 1,522 mm with an annual volume of 1,152 km3. From this total volume, 884 km3 will runoff while 268 km3 will evaporate from rivers, lakes and reservoirs. Chile's rivers are generally short, running from the Andes in the East to the Pacific in the West. The most important rivers in Chile are the Loa River in the Northern Atacama desert, the country's longest river with a length of 420 km that has suffered pollution from copper mining; the Baker River in Patagonia, the country's largest river in terms of discharge that is the site of Chile's largest planned hydropower plant with a capacity of 2,400 Megawatts; the Biobío River, the country's second longest river that became famous for the construction of controversial Pangue Dam in 1996; the Maule River in the central part of Chile that is well known for its agriculture, including its irrigated vineyards, as well at the literature and poetry it has inspired; and the Maipo River that provides the capital Santiago with drinking water and is also a major source of water for irrigation. Groundwater usage from aquifers in Chile is notably much less than of surface water. As of 1999, only 1.455 km3 was pumped out of aquifers that are recharged by nine prominent watersheds in Chile. The table below further distinguishes among fifteen administrative regions of Chile and their main hydrological characteristics. Regions I through XV correspond to Northern Chile (drier) down to Southern Chile (wetter) respectively. NOTE: *Region XIV is between IX and X; ** Region XV is northernmost. Source for tables above: FAO (2000) data updated with 2002 census figures; ***The Global Precipitation Climatology