Annex C. The Chillón, Rímac and Lurín River Basins (Chirilú)

The Chirilú River Basin, made up of the individual Chillón, Rímac and Lurín Basins, is one of the most critical basins due to its importance for the daily lives of millions of people and the country’s economy (Box A C.1). The Chillón and Rímac River Basins contribute the most to supply the water needs of the urban population of Lima, a city of 10 million inhabitants, which represents one-third of the country’s total population. A total of 69% of surface water in the area is generated by the Rímac River system, 20% by the Chillón River and 11% by the Lurín River. The latter is smaller in comparison to the other two basins and a less relevant source of water. However, the lower valley of the Lurín River Basin is considered Lima’s last “green lung” and is crucial for food supply to the city. It is also essential to the good functioning of the hydrological system in the region because it significantly supports the recharge of groundwater bodies.

This basin supplies most of the water resources for domestic and agricultural use. The main use for the water resources of the Chirilú River Basin is for domestic purposes (69%), followed by agricultural (22%) and industrial (8%) uses (MINAM, 2019[1]). In 2016, the demand for water resources reached 833.7 hm3. The total volume of available water resources in the 3 basins is 1 109 hm3, in which the Rímac River, which flows through the city of Lima, plays a very important role. The National Water Authority (ANA) has reported that most of the domestic water licences correspond to the Rímac River basin, due to the fact that it is the closest to Lima. Water licenses in the Chillón and Lurín River basins cover mostly agricultural users. The volume of water used for domestic purposes has significantly increased since 2009, where domestic demand required 753.1 hm3 and, in 2017, where domestic demand required 833.7 hm3 (75% of total surface water), which represents an increase of over 10% in less than 10 years. The water in this basin is also primarily used for energy purposes and five of the most important hydroelectric plants in the country are situated there. These plants are situated in the middle part of the Chirilú Basin, where water is harvested for power generation and is then returned to the river.

Groundwater is a much less significant source of water in the Chirilú River Basin than surface water. Approximately three-quarters of this demand is covered through surface water and the remaining 25% is supplied by groundwater (Figure A C.2). The total volume of groundwater provided by the Chillón, Rímac and Lurín aquifers amounts to 310 hm3, less than one-third of the volume provided by surface water. The Rímac aquifer, like its corresponding river basin, is the most resourceful of the three. Together, the Chillón and Rímac aquifers cover 88% of groundwater demand. According to the Lima Drinking Water and Sewerage Service (Servicio de Agua Potable y Alcantarillado de Lima, SEDAPAL), during the period 2006-13, the average abstraction flows fluctuated between 3.5 m3/s and 4.0 m3/s. Between 1997 and 2006, the abstraction flows strongly decreased from 8.3 m3/s to 4.0 m3/s (SEDAPAL, 2015[2]). Also, in the period between 1969 and 1997, abstraction flows increased from 1.1 m3/s to 8.3 m3/s, causing severe overexploitation and a decrease in phreatic strata from 30-40 to 60-80 metres. The Lima Drinking Water and Sewerage Service (SEDAPAL) established in its Optimised Master Plan a maximum abstraction flow of 3.5 m3/s for the Rímac aquifer, 1 m3/s for the Chillón aquifer and 0.3 m3/s for the Lurín aquifer (SEDAPAL, 2015[3]).

The amount of water resources available in the basin is currently insufficient to cover the amount of demand from the cities of Callao and Lima. Dealing with the threats posed by the insufficient quantity and low quality of water, in a context of strong anthropogenic pressure and vulnerability to climate change, is Chirilú’s greatest challenge. Total water availability in the Chirilú Basin is 125 m3/per capita/per year (AQUAFONDO, 2016[4]), well below the water scarcity rate of 1 000 m3/per capita/per year established by the United Nations (UN). The city of Lima is also expected to grow substantially in the next decades, reaching a population of over 12 million inhabitants by 2030 (UN, 2018[5]). Consequently, water demands for domestic and non-domestic uses are expected to increase by 10% in the next 15 years, rising from 26.8 m3/s to 31.7 m3/s in 2030 (SEDAPAL, 2015[2]). In comparison to other Latin American cities, Lima has one of the lowest per capita water resource reserves rates (Table A C.1), meaning that Lima is also ill-prepared to meet increasing water demand over the next decades. In fact, according to SEDAPAL projections, if Lima were to endure a period of drought (increasingly frequent, intense and lengthy as a result of climate change), it would not be able to provide adequate water and sanitation services to its citizens for more than two years.

Problems in water quantity are compounded by threats to water quality. The pollution of the Rímac River is one of the most serious cases of river pollution on the national scale. There are at least 1 185 sources of pollution in the Rímac River Basin, with 260 (22%) in the upstream area, 336 (28%) in the central area and 589 (50%) in the downstream area, where the urban population is concentrated (ANA, 2015[6]). As for the types of pollution sources, the number of pollution sources related to municipal wastewater is the highest, with 736 (62%), followed by sources of contamination related to solid waste, with 323 (27%), attesting to the magnitude of the city’s impact in the pollution problem (K-Water, 2015[7]). In 2016, high levels of metals were detected in the upper Rímac River Basin, mainly arsenic, manganese, iron and lead. The lower part of the Chillón River Basin presents poor water quality, with high levels of biological oxygen demand (BOD), copper, lead and thermotolerant coliforms (i.e. E. coli). The Lurín River Basin, on the other hand, presents excellent quality levels in the upper basin; however, there is a high presence of thermotolerant coliforms in the lower basin, presumably from the dumping of solid waste (ANA, 2018[8]). Monitoring results for groundwater quality show better results. The Rímac, Chillón and Lurín aquifers all generally show normal to high-quality results at the different measuring points. However, quality decreases on approach to the coastal area, where the city of Lima and the district of Callao are located (ANA, 2018[8]). In order to reach target water quality levels, ANA has put into place a Water Pollution Prevention Plan for the Rímac River (Plan Maestro para la Restauración del Río Rímac). This plan includes both structural and non-structural measures.

One of the main issues affecting the health of the rivers in the Chirilú Basin is the outcome of the informal human settlements that have appeared along the riverbanks and that contribute heavily to pollution levels, increase illegal abstraction and depletion of the aquifers, and hamper the recuperation of riparian ecosystems. One of the best-known cases is the left bank of the Rímac River (Margen Izquierda del Río Rímac, MIRR), where more than 80 000 people reside (IDRC/CRDI, 2012[9]). This area faces myriad vulnerabilities in the form of social, economic and environmental issues. Due to their proximity to the riverbank, the geophysical conditions of the terrain, seismicity and precarious constructions, these areas are much more vulnerable to water erosion and flooding, which result in many instances of houses being washed away. The lack of adequate sewerage systems leads to the dumping of untreated domestic wastewater directly into the Rímac River. Informal settlements are the result of complex social, economic and political factors that require sensible solutions for the effective disassembling of the settlements and relocation of the communities living there to improved living quarters.

The Chirilú River Basin belongs to the Cañete-Fortaleza Administrative Water Authority, which contains 17 hydrographic units and 5 Local Water Authorities (ANA, 2019[10]). The Chirilú River Basin is governed by the Chillón-Rímac-Lurín Local Water Authority, which holds competency over 9 384.61 km2, amounting to 23.50% of the total land under the auspices of the Cañete-Fortaleza Administrative Water Authority. The basins that concern Chirilú concern 78.1% of the land governed by the Chillón-Rímac-Lurín Local Water Authority, amounting to 7 329.68 km2 (ANA, 2019[11]), making this basin system the most important under its control.

Key actors in the water management system are the following:

  • The Chillón-Rímac-Lurín Local Administrative Water Authority (ALA) is a deconcentrated organ of the National Water Authority (ANA) charged with the operational management of the water resources found in the basins that constitute the Chirilú system. Given the importance of domestic use in the basin, its main function is managing the supply of drinking water.

  • The Lima Drinking Water and Sewerage Service (SEDAPAL) is the main water operator in the Chirilú Basin and the most relevant water utility in Peru. Its main mission is the provision of sanitation services such as drinking water and sewerage. It is also charged with executing sectorial policy in the operation, maintenance, control and development of basic services, with specific functions in aspects of regulation, planning, programming, project development, financing, execution of works, advice and technical assistance. It can also engage in other related and/or complementary activities. Like other urban water operators, SEDAPAL is regulated by the National Superintendence of Sewerage Services (SUNASS). Its main purpose is to regulate and supervise the provision of sanitation services by providers, independently, objectively and in a timely manner. An annual rate of 1% of total revenues from SEDAPAL’s service provision was established for the collection of PES (Box A C.2).

  • The Chillón-Rímac-Lurín River Basin Council, founded in 2016, is a space for consultation in which the institutions and other organisations of the region linked to the integrated management of water resources can present their needs, projects and claims, in order to plan and co-ordinate the sustainable use of water in the basin.

  • The Sub-sectorial Irrigation Program (PSI) is a decentralised organ of the agricultural sector. Its main objective is to promote the sustainable development of irrigation systems in the coast and mountains, the strengthening of user organisations, the development of management capacities, as well as the dissemination of the use of modern irrigation technologies to contribute to increasing agricultural production and productivity. Its overall mission is to improve the profitability of agriculture and raise farmers’ living standards.

  • The Agricultural Regional Directorate of the Regional Government of Lima (GORE Lima) is a decentralised body of the Regional Government of Lima that promotes agricultural productive activities at the regional level and depends technically and functionally on the Ministry of Agriculture.

A River Basin Council is in an advanced implementation phase to ensure the provision of continuous and quality basic water and sanitation services to the bustling City of Lima and the District of Callao. The River Basin Council for the Chillón-Rímac-Lurín basin was formally created in 2016 by the Supreme Decree 009-2016-AG. Yet, its operationalisation was not secured until 2018. The initiative was spearheaded by ANA, with the support of the regional government of Lima and Callao, which grouped potentially interested stakeholders and proposed their inclusion as members of the council. The scope of the Chirilú Council is broad: it covers 15 hydrographic units totalling 9 384.6 km2. It is composed of 19 representatives and currently contains 8 working groups (Table A C.2).

The council representatives hail from a variety of organisations and institutions, including regional governments, the Cañete-Fortaleza Administrative Water Authority, universities, agricultural and non-agricultural water user boards, local governments, peasant communities and professional associations belonging to the water sector. The council is currently presided by the Regional Government Programme of the Metropolitan Municipality of Lima.

The first objective of this council, which has been functioning for over a year, is the elaboration and successful implementation of a Water Resources Management Plan (PGRHC), which has been designed by the Technical Secretariat and is now pending approval. This plan will be the council’s main management and operating instrument. There is not yet a Chirilú PGRHC, approved by ANA. What has been advanced is the creation of working groups such as the Natural Infrastructure and Water Conservation Group, the Water Culture group, the Chirilú water observatory group, among others. Thematic groups are soon to be formed to put together the management plan. Of particular interest in this council is the extent to which its operations have advanced, including the creation of working groups with specific objectives and scopes of action (Table A C.2). The working groups not only gather council representatives but also non-governmental organisations (NGOs), private sector companies and other types of organisations in order to advance work in key areas of interest. No other River Basin Council in Peru has established working groups with the amount of outreach and institutional development as those that have been established within the Chirilú River Basin council.

In the Chirilú Basin, institutional fragmentation and lack of effective cross-sectoral co-ordination make it difficult to align policy with objectives across several institutions and sectors. For example, the issues of water quality in the city of Lima should be dealt with through the engagement of actors from the sanitation and health, housing, education and waste management sectors.

The authorities in the metropolitan area of Lima have made great progress in the use of legal and economic instruments in order to achieve more articulated and integrated basin management. However, the main planning tool is still pending approval, despite the fact that the council has been operating for over three years. The successful creation of the Chirilú River Basin Council is the clearest example of these efforts of stakeholders coming together to discuss and agree on joint objectives for better water governance. However, this process required a significant amount of time for all stakeholders to gather and agree on the fundamental structure and operation of the basin council, and while its operation has somewhat advanced, there are still impediments when it comes to the operative instruments of the council, such as the PGRHC.

Data and information on the state of water quality in the Chirilú Basin is lacking given that information is not collected every year. Moreover, there are gaps in the territorial scope of the collection, in particular in the Lurín River Basin. In addition to the lack of frequency of data collection, the data collected by ANA on groundwater quality in Lima only show an assessment of the presence of salts. Therefore, there is a lack of information regarding other pollution indicators such as pesticides, hydrocarbons, benzene, toluene, ethylbenzene and xylenes (BTEX) and heavy metals. As such, the full extent of the quality of groundwater sources is unknown.

Technical capacities are pending regarding the implementation of projects related to the MERESE funds (mentioned above as PES). As such, SEDAPAL opened a call for projects to fill this gap. MERESE funds have been collected for over 4 years in the region and a sizeable amount of funding (an estimated PEN 90 million) is available for upstream ecosystem protection. However, the operative use of these funds is lagging. There is some evidence of MERESE operating to serve the district of Callao but no projects have been implemented for Lima. SEDAPAL is in charge of collecting the funds but, due to its nature, it is not necessarily equipped with the capacity to effectively co-ordinate with upstream players and design conservation projects in order of priority.

There is a deficit of social legitimacy of some charges. Mostly industrial users paying SEDAPAL to the groundwater monitoring and management tariff in Lima have been complaining or expressing their doubts about the actual use of collected revenues. Sometimes this has even implied litigation between those users and SUNASS. Unless the necessary provisions are made, social issues may emerge due to the lack of management of the expectations of taxpayers and those implementing water management projects. In that sense, it is important to keep actors involved informed and ensure their participation in the various stages. It should also be acknowledged that the water and sanitation service company’s (EP) regulatory tariff update every five years tends to create a climate against private engagement in water services delivery and in favour of considering affordability concerns.

Co-ordination across sectors is needed to collectively deal with the problems of water scarcity and pollution in the Chirilú Basin. Institutions and operators could jointly elaborate a catalogue of issues that should be addressed and/or explored and, where possible, indicate actions that could be taken in this respect. Negative externalities on the water sector often stem from other sectors, like solid waste. As such, members of the manufacturing sector can also be involved, given the amount of waste that is produced through their activities.

More relevant and up-to-date data and information are needed for basin authorities to make efficient policies and plan for effective implementation. There is a consistent lack of updated, concise and easily accessible environmental information related to the environmental status of the Chirilú Basin and its conforming elements, including a wider variety of indicators on pollution and consumption of water resources. The difficulties in the quality of information are coupled with the fact that many institutions are in charge of collecting data. Addressing this issue to provide timely, easily accessible and transparent data should include careful consideration about what administration should be responsible for this data collection and establish priorities in terms of what categories of data need to be collected and who the target groups for such data collection should be, taking into account the economic, social and financial implications of these decisions. The creation of a water observatory as one of the working groups within the Chirilú Basin Council that has as one of its aims the collection and exchange of information is a promising initiative that will hopefully grow once the mandate of the basin council is effectively operationalised through the approval of the PGRHC.

The expertise and knowledge of private companies could be tapped to ensure more effective PES structures. Challenges showed by SEDAPAL in using the revenues from the MERESE funds effectively are an example of a capacity gap. To fill this gap, the operator is involving the private sector and associations able to implement projects related to the preservation of the basin. In fact, some of the most advanced PES projects in the Chirilú Basin are being co-ordinated through AQUAFONDO, a multisectoral platform containing members from academia, the private sector and civil society. This organisation is carrying out conservation projects both in the upper and lower basins. NGOs such as Forest Trends are also at the forefront of co-operation with SEDAPAL, especially in projects involving natural infrastructure, Furthermore, the expertise that has been generated by the Siembra y Cosecha scheme driven through the Sierra Azul Programme by the Ministry of Agriculture could be of inspiration to SEDAPAL and its partners for the design and implementation of its portfolio of conservation projects. Furthermore, there is a growing dynamism within the private sector in the region that is resulting in conservation efforts being increasingly embedded in their corporate social responsibility programmes in their respective areas of influence, beyond the actions foreseen through the PES funds. Many companies already invest private funds into the recuperation and conservation of the aquifers.

The involvement of wider civil society such as NGOs, academia and the private sector could act as a catalyst for the MERESE to take off. Actively engaging citizens in the recuperation and conservation efforts of the waters in the Chirilú Basin and empowering them as agents of change will be essential for the full recovery of the rivers’ vitality and health. Some work is already underway through their participation in the working groups (see Table A C.2). The practice of creating specific working groups to tackle areas or subjects of interest within the council is a good way to focus on specific problems and solutions while keeping the motivation high (see Table A C.2). However, particular attention should be devoted to the implementation phase and to the co-ordination across the working groups to avoid duplication and overlaps.

The public investment system needs to be adapted to these new forms of green infrastructure, as the system is designed to build rather than to conserve. As such, the releasing of the funds take place too slow to be able to effectively address the conservation efforts needed as part of the green infrastructure schemes. Financing and investment schemes should be adapted to the characteristics of natural infrastructure so that projects can be designed and implemented successfully. Transitioning from grey to green infrastructure has been flagged as an issue of national priority, especially in the Chirilú Basin where one of the working groups within the River Basin Council works specifically on the conservation of water and natural infrastructure (GT CAIN CHIRILU). Natural ecosystems – which provide key services and benefits such as the regulation of flows and erosion prevention – are indispensable in the fight against water stress in the region. Green interventions could substantially contribute to addressing the current dry season flow deficit experienced by the city of Lima at costs that are lower than, or competitive with, proposed grey infrastructure projects (Gammie and De Bievre, 2015[12]). Several civil society organisations and NGOs work with SEDAPAL to create and implement natural infrastructure projects. These interventions range from the conservation of wetlands and forests to the restoration of pre-Incan infiltration channels and the improvement of grazing practices, incorporating this issue as a pillar of the sustainable management of water resources. The development of a specific regulatory framework, new technical tools and the allocation of financial resources, are recent advances that help shift attitudes towards integrated and sustainable management of water resources.


[10] ANA (2019), Administración Local del Agua Chillón-Rímac-Lurín, Autoridad Nacional del Agua,

[11] ANA (2019), Autoridad Administrativa del Agua Cañete-Fortaleza, Autoridad Nacional del Agua,

[8] ANA (2018), Estado Situacional de los Recursos Hídricos en las Cuencas Chillón, Rímac y Lurín, ANA Repository, Autoridad Nacional del Agua,

[6] ANA (2015), Plan maestro del proyecto de restauración del río Rímac: informe final, (accessed on 12 March 2021).

[4] AQUAFONDO (2016), Estudio de Riesgos Hídricos y Vulnerabilidad del Sector Privado en Lima Metropolitana y Callao en un Contexto de Cambio Climático,

[12] Gammie, G. and B. De Bievre (2015), “Assessing green interventions for the water supply of Lima, Peru”, Forest Trends,

[9] IDRC/CRDI (2012), Sistematización: Una experiencia de investigación acción participativa de reducción de la vulnerabilidad en la Margen Izquierda del Rio Rímac del Cercado de Lima, Proyecto Ciudades Focales,

[7] K-Water (2015), Plan Maestro para el Proyecto Restauración del Río Rímac: Informe Final, ANA Repository,

[1] MINAM (2019), Ficha Técnica “Cuenca de Los Ríos Chillón, Rímac y Lurín (CHIRILÚ)”.

[2] SEDAPAL (2015), Afianzamiento hídrico para el abastecimiento de agua para Lima Metropolitana, (accessed on 12 March 2021).

[13] SEDAPAL (2015), Afianzamiento Hídrico Para el Abastecimiento de Agua para Lima Metropolitana,

[3] SEDAPAL (2015), Plan Maestro Optimizado 2015 - 2044, (accessed on 12 March 2021).

[14] SEDAPAL (2015), Plan Maestro Optimizado 2015-2044,

[5] UN (2018), The World’s Cities in 2018, United Nations,

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