The Right to Sewage: Digesting Mexico City in the Mezquital Valley

Almost 200,000 acres of land in the fertile Mezquital Valley are irrigated with the untreated sewage of Mexico City. Rainwater, urban runoff, industrial effluent, and sewage in Mexico City are sent to the Mezquital Valley through a 60-kilometer pipe. Soils in this valley have been continuously irrigated with urban wastewater since 1901, longer than any other soil in the world. The capacity of these soils to produce conditions in which agriculture can be safely practiced and produce healthy crops depends on complex interactions between soil composition, chemistry, ecosystem function, farming practices, public policy, land management, and the urban design of Mexico City’s hydraulic infrastructure. Without this wastewater, the Mezquital Valley would be a desert, as it falls into the United Nation’s “drylands” climate category, where rates of evapotranspiration exceed precipitation. Currently, more than 40 percent of the world is classified as “drylands,” making the Mezquital an important case study in wastewater reuse for a warming world. The goal of this research project was to evaluate the successes and failures of the Mezquital Valley as the world’s largest experiment fertilizing agriculture with human wastewater. What hydraulic, soil, ecosystem, social, and policy conditions increase chances for success? What are its prospects for socioecological sustainability? In order to address these questions, we partnered with farmers, urban water experts, and soil scientists in order to understand both sides of the wastewater pipe as part of the same agricultural system. This research produced an advanced studio curriculum at Harvard University on the architecture of postnatural soils.

Bonhevi Rosich and Denizen’s presentation was followed by a conversation with respondents Teresa Galí-Izard (professor of Landscape Architecture at ETH Zurich and head of Arquitectura Agronomia), Christina Siebe (senior researcher at the department of Soil and Environmental Sciences of the Institute of Geology at the Universidad Nacional Autónoma de México), and Elena Tudela (associate professor at the Facultad de Arquitectura, Universidad Nacional Autónoma de México, and cofounder of the Office of Urban Resilience).

Presenters

Montserrat Bonvehi Rosich is a licensed Spanish architect and urban designer with an interest in living systems, climate, and soils in urban environments. Her ongoing project “The Landscape We Eat” seeks to unfold geomorphological, climatic, and infrastructural relationships in food systems. The work was launched as a performance at CA2M contemporary art museum in Madrid, exhibited in Milan’s EXPO 2015, and included different publications such as Food Atlas. She is currently teaching in the Department of Landscape Architecture at the Harvard University Graduate School of Design, where she was named the 2017–2018 Daniel Urban Kiley Fellow. Previously she has taught both architecture and landscape architecture at the University of Virginia, as well as architecture and industrial design at Iowa State University and urban design at Escola Tècnica Superior d'Arquitectura de Barcelona-Universitat Politècnica de Catalunya (ETSAB-UPC). Her designs, built and unbuilt, have received several awards and have been published in Detail, Plataforma Arquitectura, and Quaderns, among others.

Seth Denizen is a writer, researcher, and design practitioner trained in landscape architecture and human geography. In 2019 Denizen completed a PhD at the University of California, Berkeley in Geography, where his research investigated the vertical geopolitics of urban soil in Mexico City. In addition to his geographical work he has published widely on art and design with the Asia Art Archive, LEAP International Art Magazine of Contemporary China, Volume, and Fulcrum, among others. He is currently a member of the editorial board of Scapegoat Journal: Architecture/Landscape/Political Economy. Collaborations include scientific research on Hong Kong’s urban microbiome, as well as art exhibitions in the Blackwood Gallery (Toronto), The Kunsthal (Netherlands), and Para/Site Art Space (Hong Kong). He currently teaches at the Sam Fox School of Design & Visual Arts at Washington University.

Respondents

Teresa Galí-Izard is a professor of Landscape Architecture and program director of the new Master of Sciences in Landscape Architecture at ETH Zurich in Switzerland. She also heads Arquitectura Agronomia, a landscape architecture firm based in Barcelona. In the last twenty years she has been involved in some of the most important contemporary landscape architecture projects in Europe including TMB Park, Coastal Park, the new urbanization of Passeig de Sant Joan in Barcelona, and the Vall d’en Joan Landfill restoration, which won the European Prize for Urban Public Space in 2004. Through her work, Galí-Izard explores new languages and forms while working with living materials such as earth, water, and vegetation and using a contemporary approach involving dynamics and management. Galí-Izard is the author of The Same Landscapes: Ideas and Interpretations (Gustavo Gili, 2005) and coeditor with Daniela Colafranceschi of Jacques Simon: Los otros paisajes, Ideas y reflexiones sobre el territorio (Jacques Simon: Other Landscapes, Ideas and Reflections on Territory, Gustavo Gili, 2012).

Christina Siebe is a senior researcher at the department of Soil and Environmental Sciences of the Institute of Geology at the Universidad Nacional Autónoma de México (UNAM). She received her PhD from the University of Hohenheim, Germany, in 1994. She studies soil degradation processes in peri-urban and urban environments, with a special focus on waste management strategies that promote water and nutrient cycling. She oversees a Critical Zone Observatory at the Mezquital Valley where wastewater has been reused for agriculture for more than a century. She currently coordinates the graduate program in Earth Sciences at UNAM, is an editor of the journal Catena, and represents the German Science Foundation in Mexico.

Elena Tudela has a degree in Architecture from the Facultad de Arquitectura at the Universidad Nacional Autónoma de México (UNAM) and a master's degree in Architecture in Urban Design from the Harvard University Graduate School of Design. She is a PhD Candidate in Architecture at UNAM. She was urban design coordinator of the project Parque Hídrico Quebradora (IIS-UNAM) in Iztapalapa, Mexico City, which received the 2017 Regional Gold award and the 2018 Global Gold from LafargeHolcim Sustainable Awards. She worked at the General Office of Strategic Projects of the Secretary of Urban Development and Housing of Mexico City and at the Public Space Authority, also of Mexico City’s government. Tudela is an associate professor at the Facultad de Arquitectura UNAM and cofounder of the Office of Urban Resilience (ORU), an urban design firm specializing in water infrastructures, landscape, and public space. She cocurated, along with Isadora Hastings and Mauricio Rocha, Mexico’s National Pavilion “Displacements” at the 17th Architecture International Exhibition Biennale di Venezia 2021. She is a member of the Advisory Council for Public Space and the Resilience Council of Mexico City and is part of the National System of Art Creators for Mexico’s Ministry of Culture since 2020.