water resources management in peru water resources management in peru while peru accounts for about four per cent of the world's annual renewable water resources, over 98% of its water is available east of the andes, in the amazon region. the coastal area of peru, with most of economic activities and more than half of the population, receives only 1.8% of the national freshwater renewable water resources. economic and population growth are taking an increasing toll on water resources quantity and quality, especially in the coastal area of peru. not to be confused with water supply and sanitation in peru or irrigation in peru. water resources management in peruwithdrawals by sector 2000/2001 domestic: 12% agriculture: 80% industry: 8% renewable water resources1,913 km³surface water produced internally1,616 km³groundwater recharge303 km³overlap shared by surface water and groundwater303 km³external renewable water resources297 km³dependency ratio15.5%renewable water resources per capita58,321 m³/yearwetland designated as ramsar sites68,000 km²hydropower generation72% the government of peru is currently undertaking a major transformation of its water resources management from a centralized approach focused on irrigation development in the coastal area to a river basin integrated water resources management for the entire country. the 2009 water resources law (ley de recursos hídricos) and the draft national water resources management strategy of 2004 (estrategia nacional para la gestión de los recursos hídricos continentales del perú) contain the necessary elements for integrated water resources management as stated in international good practices namely, integration of sectoral policies, participation of stakeholders, decentralization of management to the river basin level and recognition of water as a social and economic good. despite the new law, several key challenges remain, including limited institutional capacity, increasing water stress in the coastal region, deteriorating water quality, poor efficiency in the irrigation sector, as well as inadequate access to and poor quality of water supply and sanitation. water management history and recent developments the second half of the 20th century witnessed heavy public investments in dams in the andes and associated irrigation infrastructure in the coastal region. for example, in the 1950s and 1960s, the san lorenzo dam and tinajones dam, the largest peruvian dams, were built in the northern coastal region. within the government the ministry of agriculture was given the responsibility to manage water resources, since irrigation was by far the largest water use. its lead role was confirmed by the 1969 general water law no. 17752 (ley general de aguas—lga) which defined the ministry of agriculture as the "national water authority". however, other laws—such as the general hydrocarbon law (dl 26221), the general mining law (ds 014-92-em), the law for electricity concessions (dl 25844)—also dealt with water resources on a sectorally fragmented basis within a centralized administrative system that gave little or no decision-making power to stakeholders at the local level. there was no legal basis for integrated water resources management at the level of each river basin, and consequently there were no institutions to implement such an integrated management. this began to change in the early 2000s with the approval of a decentralization law, a regional government law and a municipalities law. in 2003 the government began transferring powers to the newly created regional governments, including for water quality management and the operation and maintenance of major public infrastructure, despite the limited institutional capacity of regional governments. a draft national water resources management strategy prepared in 2004 (estrategia nacional para la gestion de los recursos hidricos continentales del peru) aimed at promoting integrated water resources management through a new institutional and legal framework. in this spirit a national water authority (autoridad nacional del agua – ana) was established in 2006 and its role was strengthened through the 2009 water resources law (ley de recursos hídricos – lrh). implementation of the law and the creation of basin-level institutions with meaningful capacities and enforcement powers still remain a challenge. (see legal and institutional framework below for more details) water resource base surface and ground water resources topographic map of peru peru has a large amount of water resources, with 159 river basins and a per capita availability of 68,321 cubic meters (m3) in 2006. according to fao the long-run average annual rainfall is 1,738 millimeters (mm). there is significant seasonal variability in river run-offs, two-thirds of which occur between january and april. map of lake titicaca the andes divide peru into three natural drainage basins: pacific basin (279,000 km2), atlantic basin (959,000 km2) and lake titicaca basin (47,000 km2). according to the national water authority (autoridad nacional del agua—ana), the pacific basin has 62 rivers; the atlantic basin has 84 rivers; and lake titicaca basin has 13 rivers. the number of rivers in peru varies depending on the source of information, because in some cases tributaries are counted as rivers in their own right and in other cases not. according to ana, the dry pacific basin, with 37.4 km³ available per year, accounts for less than 2% of peru's renewable water resources. its 62 rivers flowing west from the andes supply the bulk of the water to the coastal region. of these rivers, only about 30% are perennial. from 1984 to 2000, the average water availability decreased to 33 km³ per year and from 2003 to 2004 to 20 km³ per year. agriculture accounts for the withdrawal of 14 km³ per year (or 80% of total water use) and domestic withdrawals account for 2 km³ per year (12% of total water use). the atlantic basin holds more than 97% of all available water with nearly 2,000 km³ per year. agriculture also accounts for 80% of water use, while domestic use accounts for 14%. the lake titicaca basin receives 10 bcm per year, less than 1% of the total. in this basin, agriculture accounts for 66% of total water use, while domestic use accounts for 30%. key characteristics of the drainage basins drainage basin population (1,000) water availability (km³) per capita water availability (m³) number of river basins pacific 18,430 37.4 2,027 62 atlantic 6,852 1,999 291,703 84 titicaca 1,047 10.1 9,715 13 total 26,392 2,046.3 77,534 159 source: inei (2007) external resources of water enter peru though tributaries of the amazon, in the atlantic river basin, supplying 125 bcm annually. the main rivers are napo, tigre, pastaza, santiago, morona, cenepa, and chinchipe. ana estimates the total amount of groundwater available on the coast to be between 35 and 40 km³. there is specific data available only for eight valleys on the coast with 9.0 km³ of groundwater available. around 1.8 km³ of water are actually extracted on the coast. no sufficient information is available regarding groundwater availability and withdrawal in the highland and amazon regions. groundwater withdrawal per sector in peruvian coast (5) sector water withdrawal (million m³) water withdrawal (% of total withdrawal) urban 367 20 agricultural 911 50 industrial 553 30 source: ana storage capacity and infrastructure in 1980, the former national institute of natural resources (inrena) established an inventory of peru's water storage capacity, including lakes and dams. peru has 12,201 lakes, 3,896 of which are located in the pacific basin, 7,441 in the atlantic basin, 841 in the titicaca basin, and 23 in the closed basin of warmiqucha. inrena inventoried 186 lakes in operation with a total capacity of 3,028.07 million cubic metres and 342 studied lakes with a total capacity 3,953.04 million cubic metres. according to the inventory, the largest number of lakes in operation were located in the pacific basin, with 105 lakes and a total capacity of 1,378.58 million cubic metres, followed by the atlantic basin with 76 lakes and a capacity of 1604.73 million cubic metres. the pacific basin also has the largest number of studied lagoons, with a total of 204 lakes and a total capacity of 616.62 million cubic metres, followed by the atlantic basin with 133 lakes and a capacity of 3,006.42 cubic metres. peru also has 23 dams with a total capacity of 1,941.88 million cubic metres, and 238 studied dams with a total capacity of 44,028.04 million cubic metres. the pacific basin has 21 dams in operation with a total capacity of 1,875.88 million cubic metres; the atlantic basin has 2 dams with a capacity of 66,000 million cubic metres. the pacific basin also has the largest number of studied dams, a total of 126 with a capacity of 17,200.60 million cubic metres. the atlantic basin has 105 with a storage capacity of 26,274.83 million cubic metres. the largest reservoirs are poechos with a capacity of 1,000 million cubic metres, tinajones with 320 million cubic metres, san lorenzo with 258 million cubic metres, and el fraile with 200 million cubic metres, all of them in the coastal region. water quality the gradual decrease in peru's water quality is due to the release of untreated effluents from mining, industries, municipalities and polluted runoff from agriculture. of the 53 rivers in the coastal area, 16 are polluted by lead, manganese and iron threatening irrigation and potable water supplies. in particular, the ministry of agriculture considers "alarming" the quality of seven rivers: the mantaro and tambo rivers in the central andes that drain towards the amazonas; the small moche river near the northern coastal city trujillo and the santa near the northern coastal city chimbote; the chillon and rimac rivers near lima; and the chili river near arequipa which is well known for its rafting. in the mantaro basin alone 18 mining facilities discharge polluted water into the river. pollution from mining mining, which provided more than 60% of peru's export earnings in 2006, is a major water user and polluter. it is estimated that mining uses about 5% of peru's water. in addition, it severely affects water quality. it has been estimated that more than half of peru's peasant communities have been affected by mining activities, leading to the creation of organizations such as the national committee of mine affected communities (conacami). the government had to declare an environmental state of emergency at several mining sites due to environmental disasters. for example, in july 2008 it declared a state of emergency at a mine near lima over fears that arsenic, lead and cadmium from its tailings dam could pollute the main water supply for the capital. in july 2010 the government declared another state of environmental emergency in the central mining district of huancavelica after a wastewater storage dam of the caudalosa chica company collapsed and leaked water laden with heavy metals into local rivers. the city la oroya on the mantaro river in central peru where the company doe run operates a big mining complex has been ranked as one of the 10 most contaminated cities in the world in 2007. furthermore, an estimated 100,000 small-scale informal miners pollute rivers with cyanide and mercury. often the exact scope of pollution is a matter of dispute. an example is the yanacocha mine in the andes, the largest and most profitable gold mine in latin america that was created with the support of the international finance corporation (ifc). according to a report in 2000 by an organization called "project underground" levels of copper were 10 to 20 times higher than who standards and the acidity of the water was extremely high with a ph of 3.3 compared to 6.5, the highest acidity considered drinkable. according to local communities, fish and frogs had disappeared from the river, both of which were previously a food supply for the rural communities. subsequently, an independent report by stratus, a colorado consultancy, found that the pollution from the mine "posed no threat to human health or to drinking water". but the mine's rapid expansion has affected farmers: several irrigation channels have dried up, while extra sediment in rivers has killed trout. in almost all cases, local communities are overwhelmingly opposed to mining because of its environmental impact on their livelihoods. an example are conflicts witnessed in piura province since 1993. a canadian mining company departed shortly after a local referendum in tambogrande in which over 93% voted against mining. when another company began exploration in ayabaca and huancabamba, this elicited new conflicts and a referendum held in september 2007, in which again over 90% of voters voted against mining. one of the main concerns of local and downstream communities relates to the effects that the mine would have on water quality and quantity. the