Multiple Use Systems for Urban and Agricultural Demand
Summary
Mexico City has developed multiple-use water systems to meet both urban and agricultural demand: the megacity receives first-use freshwater from rural areas in surrounding states through inter-basin transfers and, in return, sends agricultural producers (both in other states and in the city's peri-urban peripheries) treated municipal wastewater for use in irrigation.
Mexico City's water supply relies heavily on inter-basin transfers of freshwater from surrounding regions, in particular, from the Lerma and Cutzamala systems, which supply 43% of the megacity's water (Engel et al., 2011; Freeman et al., 2020). These regions, however, are agricultural producers and the constant use of their water to provide a distant megalopolis' water supply has resulted in tensions in the Lerma and Cutzamala river basins (Engel et al., 2011; Sosa-Rodriguez, 2010; Tortajada, 2006).
Intervention
Mexico's national water authority, CONAGUA (Comisión Nacional del Agua), in conjunction with local and municipal governments in Mexico City and beyond, created the Water Sustainability Program (WSP) for the Valley of Mexico in 2007 (CONAGUA, 2008). The WSP was a subproject of the National Water Program (NWP), a 5-year program launched by CONAGUA to ensure water sustainability and security for all Mexican citizens and enable dignified, sustainable urban development in the future (CONAGUA, 2008). CONAGUA's WSP was a multifaceted program dedicated to tackling a number of key issues, including the provision of bulk water supply, storm-water drainage and wastewater treatment in the Mexico City Metropolitan Region (ZMCM) for the period of 2007-2012. More specifically, the WSP addressed the need to balance the water demand between Mexico City and the agricultural producers in the area. As such, balancing water and food security and balancing the water needs of urban and rural populations were among the primary drivers behind the program. The WSP program was funded through a combination of private sector Build-Operate-Transfer (BOT) projects, federal funds from CONAGUA's budget, the National Infrastructure Fund, loans from a state-owned investment bank, and a trust fund created by the Federal District, the State of Mexico and the federal Mexican government (IANAS, 2015; OECD, 2004).
As part of the WSP, CONAGUA defined a wastewater treatment, reuse and exchange program, that hinged upon two-way inter-basin transfers (i.e. to and from Mexico City). Specifically, wastewater from Mexico City leaves the city through one of the city's 'deep drains' (i.e. wastewater tunnels) until it reaches a treatment plant (e.g. Atotonilco Wastewater Treatment Plant in Hidalgo State or Cerro de la Estrella Wastewater Treatment Plant in the city's southern periphery) where the municipal wastewater is treated. Thereafter, treated wastewater in Hidalgo State is distributed to agricultural producers for use in irrigation outside of the city while treated wastewater from Cerro de la Estrella is distributed to agricultural producers in Xochimilco (the city's southern periphery). Similarly, treated wastewater is also sent to the Vaso del Christo area and the Tula and Mezquital Valleys for use in irrigation, in exchange for first-use groundwater and freshwater (IANAS, 2015).
Challenges
Despite the program's success in integrating wastewater reuse as a fundamental part of Mexico City's water management policy, issues related to inter-basin transfers still remain. Specifically, conflicts due to inter-basin transfers and the externalization of Mexico City's water scarcity remain a challenge. In the Lerma basin, transfers have decreased water availability for local demand, resulting in decreased soil fertility and a dependence on rain-fed (as opposed to irrigated) agriculture, and it is unclear to what degree agricultural producers in the Lerma basin benefit from the wastewater exchange program (Tellman et al., 2018; Tortajada, 2006; Sosa-Rodriguez, 2010). In the Cutzamala basin, indigenous groups feel threatened by the constant use of their land and resources to meet the distant megacity's needs, while homes in their own communities remain without access to a potable water supply (Engel et al., 2011; Sosa-Rodriguez, 2010; Tortajada, 2006).
Outcomes
Although the WSP ended in 2012, wastewater treatment, reuse and exchange remains an active and important part of Mexico City's water resources management strategy. Overall, it makes better use of all existing water resources in the megacity through careful and integrated water resources management. Treated wastewater, which is naturally nutrient-rich and good for irrigation, is sent to agricultural users in exchange for first-use groundwater and other potable supply sources. As such, the wastewater can be treated moderately (thereby saving money, time and energy) while still remaining of suitable quality for use in irrigation. Similarly, first-use water (which also necessitates less treatment for potable use than reclaimed water) can be used for municipal and urban consumption. As such, the wastewater treatment, reuse and exchange program is an example of effective management of water resources to ensure both food and water security, as well as balance the needs of rural (i.e. agricultural) and urban users (IANAS, 2015).
Since the completion of the WSP, Mexico City has continued to implement projects aimed at enhancing water security in the megalopolis. Although not a direct result of the WSP, the city started a 'water culture' campaign, seeking to inform the megacity's populace about its water system and encourage conservation. Fundamental aspects of the campaign include educating the public about urban water metabolism (i.e. from source to tap to sewage and reuse), the importance of water conservation (and ways to integrate conservation into daily life), and the megacity's reliance on multiple use systems in order to foster understanding among Mexico City's many citizens that the water they use is not solely theirs, but rather, a shared resource.
References
Multiple Use Systems for Urban and Agricultural Demand
Summary
Mexico City has developed multiple-use water systems to meet both urban and agricultural demand: the megacity receives first-use freshwater from rural areas in surrounding states through inter-basin transfers and, in return, sends agricultural producers (both in other states and in the city's peri-urban peripheries) treated municipal wastewater for use in irrigation.
Mexico City's water supply relies heavily on inter-basin transfers of freshwater from surrounding regions, in particular, from the Lerma and Cutzamala systems, which supply 43% of the megacity's water (Engel et al., 2011; Freeman et al., 2020). These regions, however, are agricultural producers and the constant use of their water to provide a distant megalopolis' water supply has resulted in tensions in the Lerma and Cutzamala river basins (Engel et al., 2011; Sosa-Rodriguez, 2010; Tortajada, 2006).
Issue
Intervention
Mexico's national water authority, CONAGUA (Comisión Nacional del Agua), in conjunction with local and municipal governments in Mexico City and beyond, created the Water Sustainability Program (WSP) for the Valley of Mexico in 2007 (CONAGUA, 2008). The WSP was a subproject of the National Water Program (NWP), a 5-year program launched by CONAGUA to ensure water sustainability and security for all Mexican citizens and enable dignified, sustainable urban development in the future (CONAGUA, 2008). CONAGUA's WSP was a multifaceted program dedicated to tackling a number of key issues, including the provision of bulk water supply, storm-water drainage and wastewater treatment in the Mexico City Metropolitan Region (ZMCM) for the period of 2007-2012. More specifically, the WSP addressed the need to balance the water demand between Mexico City and the agricultural producers in the area. As such, balancing water and food security and balancing the water needs of urban and rural populations were among the primary drivers behind the program. The WSP program was funded through a combination of private sector Build-Operate-Transfer (BOT) projects, federal funds from CONAGUA's budget, the National Infrastructure Fund, loans from a state-owned investment bank, and a trust fund created by the Federal District, the State of Mexico and the federal Mexican government (IANAS, 2015; OECD, 2004).
As part of the WSP, CONAGUA defined a wastewater treatment, reuse and exchange program, that hinged upon two-way inter-basin transfers (i.e. to and from Mexico City). Specifically, wastewater from Mexico City leaves the city through one of the city's 'deep drains' (i.e. wastewater tunnels) until it reaches a treatment plant (e.g. Atotonilco Wastewater Treatment Plant in Hidalgo State or Cerro de la Estrella Wastewater Treatment Plant in the city's southern periphery) where the municipal wastewater is treated. Thereafter, treated wastewater in Hidalgo State is distributed to agricultural producers for use in irrigation outside of the city while treated wastewater from Cerro de la Estrella is distributed to agricultural producers in Xochimilco (the city's southern periphery). Similarly, treated wastewater is also sent to the Vaso del Christo area and the Tula and Mezquital Valleys for use in irrigation, in exchange for first-use groundwater and freshwater (IANAS, 2015).
Challenges
Despite the program's success in integrating wastewater reuse as a fundamental part of Mexico City's water management policy, issues related to inter-basin transfers still remain. Specifically, conflicts due to inter-basin transfers and the externalization of Mexico City's water scarcity remain a challenge. In the Lerma basin, transfers have decreased water availability for local demand, resulting in decreased soil fertility and a dependence on rain-fed (as opposed to irrigated) agriculture, and it is unclear to what degree agricultural producers in the Lerma basin benefit from the wastewater exchange program (Tellman et al., 2018; Tortajada, 2006; Sosa-Rodriguez, 2010). In the Cutzamala basin, indigenous groups feel threatened by the constant use of their land and resources to meet the distant megacity's needs, while homes in their own communities remain without access to a potable water supply (Engel et al., 2011; Sosa-Rodriguez, 2010; Tortajada, 2006).
Outcomes
Although the WSP ended in 2012, wastewater treatment, reuse and exchange remains an active and important part of Mexico City's water resources management strategy. Overall, it makes better use of all existing water resources in the megacity through careful and integrated water resources management. Treated wastewater, which is naturally nutrient-rich and good for irrigation, is sent to agricultural users in exchange for first-use groundwater and other potable supply sources. As such, the wastewater can be treated moderately (thereby saving money, time and energy) while still remaining of suitable quality for use in irrigation. Similarly, first-use water (which also necessitates less treatment for potable use than reclaimed water) can be used for municipal and urban consumption. As such, the wastewater treatment, reuse and exchange program is an example of effective management of water resources to ensure both food and water security, as well as balance the needs of rural (i.e. agricultural) and urban users (IANAS, 2015).
Since the completion of the WSP, Mexico City has continued to implement projects aimed at enhancing water security in the megalopolis. Although not a direct result of the WSP, the city started a 'water culture' campaign, seeking to inform the megacity's populace about its water system and encourage conservation. Fundamental aspects of the campaign include educating the public about urban water metabolism (i.e. from source to tap to sewage and reuse), the importance of water conservation (and ways to integrate conservation into daily life), and the megacity's reliance on multiple use systems in order to foster understanding among Mexico City's many citizens that the water they use is not solely theirs, but rather, a shared resource.
Issues |
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Water Scarcity and Access |
Solutions |
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Integrated Water Resources Management (IWRM) |
References
Comisión Nacional del Agua (CONAGUA). (2008) National Water Program 2007-2012 (2008). Secretaría del Medio Ambiente y Recursos Naturales. Tlalpan, D.F, México. Retrieved from: http://www.conagua.gob.mx/CONAGUA07/Contenido/Documentos/PNH_Ingles.pdf.
Engel, K., Jokiel, D., Kraljevic, A., Geiger, M., & Smith, K. (2011). Big Cities. Big Water. Big Challenges. Water in an urbanizing world. WWF.
Freeman, S. S. G., Brown, C., Cañada, H., Martinez, V., Nava, A. P., Ray, P., ... & Wi, S. (2020). Resilience by design in Mexico City: A participatory human-hydrologic systems approach. Water Security, 9, 100053.
Inter-American Network of Academies of Sciences (IANAS). (2015). Urban water: challenges in the Americas: a perspective from the Academies of Sciences. Tlalpan, Distrito Federal, Mexico.
Organisation for Economic Co-operation and Development (OECD). (2004). OECD Territorial Reviews: Mexico City. OECD.
Sosa-Rodriguez, F. S. (2010). Impacts of water-management decisions on the survival of a city: from ancient Tenochtitlan to modern Mexico City. International Journal of Water Resources Development, 26(4), 675-687.
Tellman, B., Bausch, J. C., Eakin, H., Anderies, J. M., Mazari-Hiriart, M., Manuel-Navarrete, D., & Redman, C. L. (2018). Adaptive pathways and coupled infrastructure: seven centuries of adaptation to water risk and the production of vulnerability in Mexico City. Ecology and Society, 23(1).
Tortajada, C. (2006). Water management in Mexico City metropolitan area. Water Resources Development, 22(2), 353-376.