The most pressing environmental challenge of our time consists in imagining an alternative development that uses ecosystems sustainably and offers dignified, creative, and solidary living conditions and employment. This horizon, which we could name sustainable societies, unfortunately has not yet been fully established in the greater part of development plans and projects implemented in the world and, specifically, in our country. Within this challenge, without a doubt water represents the first step for any other activity of social life, since access to water together with an adequate climate has represented the starting point of great civilizations in at least the last 3000 years. In our country this was not the exception; the fertile valleys of the center of the Trans-Mexican Volcanic Belt offered the first inhabitants the conditions for establishment and development for rich and valuable civilizations; this is what archaeological evidences show in the cultural urbanistic complexes of Cacaxtla, Xochitécatl and Cholula, among others. It is in this context where we find the presence of the Zahuapan River and its tributaries within the state of Tlaxcala, which has been the articulating axis of the development of multiple urban and industry settlements. The Zahuapan River is located in the high part of the Balsas Basin, which gives it a strategic location for its conservation. Thus, the book Zahuapan: River-Region-Pollution, coordinated by professors Raúl Jiménez Guillén and María de Lourdes Hernández Rodríguez, both researchers in El Colegio de Tlaxcala, addresses the environmental problematic of the Zahuapan River in the state of Tlaxcala.

The book was designed in four parts: in the first, which addresses the theme of pollution of the Zahuapan River, the authors Rafael Villalobos Pietrini, Ana Rosa Flores Márquez and Sandra Gómez Arroyo study the problem of the river’s contamination from the effects of the industrial activities, through a technique that consists in exposing roots of Vicia faba, that is, broad bean, to the river water and later recording the chromosome alterations in the growth meristems of that plant. Evidences of chromosome damage are found from their work in three river tributaries. With this, possibilities of continuing with this type of trials are opened, among others, as useful monitoring tools of river pollution. In the second study of the first part of the book, the authors Juan Suárez Sánchez, Miguel F. Carreón Coca, Silvia Chamizo Checa and Saturnino Orozco Flores present a detailed study of water balance simulation of the Zahuapan River basin. For this purpose, they use the software Evaluation of Water and Planning Systems, where they evaluate the behavior of two variables: water availability and river pollution from organic material, considering constant growth rates of the population and changes in precipitation from the impacts of climate change. This type of studies contributes very valuable elements for decision making in the management of the basin from the so-called work units and from which an adequate institutional action plan and active citizen participation can be designed. The next study is an interesting study of the presence of metals and metalloids in the Zahuapan River sediments. According to the authors this is the first study of its type in the Zahuapan River. Its importance lies in understanding the presence and magnitude of potentially toxic metals for the ecosystem and for human health. Although the results are still not conclusive, they do point to a clear research line that should be strengthened. Later, the authors Juan Suárez Sánchez, Miguel F. Carreón Coca, Silvia Chamizo Checa and Saturnino Orozco Flores present a simulation of water balance in the Zahuapan River basin; for this purpose, they use the software Evaluation of Water and Planning Systems, where they evaluate the behavior of two variables: water availability and river pollution from organic matter, considering constant growth rates of the population and changes in precipitation from the impacts of climate change. This type of studies contributes very valuable elements for decision making of the basin management, from the so-called work units and from which an adequate plan of institutional action and active citizen participation can be designed. The third study of the first part is an interesting study of the presence of metals and metalloids in the sediments of the Zahuapan River. According to the authors this is the first of its kind in the Zahuapan River. Its importance lies in understanding the presence and magnitude of potentially toxic metals for the ecosystem and for human health. Although the results are still inconclusive, they do point to a clear line of research that must be strengthened.

The second part of the book that develops the theme of the social and historical context begins with the study by Ricardo Nava Olivares which documents and shows that the historical pattern of settlement of the industrial corridor of the Zahuapan River has its basis in a pre-Hispanic territorial planning system and which, in addition to having a north-south orientation, also presents an outline following the pattern of more than 100 tributaries of the Zahuapan River. The next study by Maura Pérez Jaramillo is an excellent approximation to what we could call the phenomenology of the Zahuapan River, where the Zahuapan River is described in the style of Merleau Ponty, at times melancholic and others idyllic. This chapter approaches the knowledge of the river experienced by the local population. Without a doubt it is a research line about the perception of rivers that should be fostered as a complement to other river research approaches. The next chapter by Ramos Montalvo Vargas elaborates, from the dominion of digital terrain models and of geographic information systems, an excellent characterization of the state of Tlaxcala and particularly the Zahuapan Basin, following as a research lead the conflict between the altimetric conditions and three elements: the productive potential of the primary sector, risks from flooding, and territorial planning. For this purpose, it builds different terrain profiles in order to outline and make visible these conflicts in territorial zoning. Doubtless, this is a strategic effort for territorial planning of the Zahuapan River basin, which, according to the author, should be complemented with an interdisciplinary approach. In the next chapter, written by Vidal Guerra de la Cruz, Juan Islas Gutiérrez and Enrique Buendía Rodríguez, the relationship between soil erosion in the region of Atoyac Zahuapan and socioeconomic welfare indicators is addressed. This is important work in incorporating the socioeconomic dimension into the basin dynamics. Its results, as the authors clearly point out, must be studied in depth, so as not to fall into explanations that could be “evident” and even justifiable within a certain logic: with higher erosion, higher poverty. The study which closes the second part of the book was written by Enriqueta Tello García, David Pájaro Huerta and Patricio Sánchez Guzmán. It is a valuable work in peasant ethnic soil science in the municipality of Nativitas, Tlaxcala, which shows the living peasant knowledge and classification of five different types of river soils. This study opens the possibility of a waterway territorial zoning of the Zahuapan River banks, taking into account the peasant knowledge of soils, something possible unprecedented in the world.

The third part of the book, devoted to management, opens with the work by María de Lourdes Hernández Rodríguez, who addresses the theme of water conflicts through a comparative descriptive method, using a double-entry table. The study contributes a valuable exploration into this issue that deserves to continue being studied at depth, in order to build working hypotheses that explain better the strategic role that the author mentions state and municipal governments have in the conflicts identified. The next chapter is written by Guillermo Aragón Loranca, who develops a detailed case study of the Las Cunetas Dam, which was the site where in 2005 the high-level report of fish mortality in the dam was documented, associated to several accidents in the nearby industrial corridors. The author performs a detailed documental study that comes to question the authorities’ actions to make law prevail in favor of environmental protection; with this, the scenario described in previous chapters is complemented, highlighting the complexity of water management in the Zahuapa River basin, which touches with a research situation of transdisciplinary type. The next chapter is written by María Elza Eugenia Carrasco Lozano and addresses the theme of the perception of water scarcity, specifically from the perspective of women, recognizing that he role of women is a central element in the supply, management and protection of water in our rural and urban societies, so that an inclusive water policy is proposed in benefit of equity and justice for women. The following work, by José Dionicio Vázquez Vázquez, develops a greatly current and relevant theme, which is recent migration and immigration within the context of availability and access to water services in the Zahuapan Basin. This is probably the circumstantial theme of greatest relevance that the book specifically contributes. Without a doubt it is an aspect that recognizes the need to review the capacities of the Mexican State in general and the state of Tlaxcala in particular to be able to receive and accompany the migratory return flows and domestic migration towards the Zahuapan Basin, in terms of taking care of ecosystems, food production, housing, education, jobs, and naturally, access to water and its corresponding treatment.

The fourth and last part of the book that outlines the field of economy, planning and public policy begins with the study by Américo Saldívar Valdés and Sacha Marcelo Olivera. They approach a very important theme for the planning of sustainable management of the Zahuapan River hydrologic basin, related to environmental accounting. The authors carry out a detailed study of the economic benefits that the river’s sanitation would imply. For this purpose, they account for the decrease in morbidity rates provoked by diseases related to or due to bad water quality, in the long term, and the possible promotion of economic development in potentially profitable activities. Their results show that the benefit/cost analysis expected by sanitation of the river water contributes a coefficient of 1.12, which means that the economic benefits expected are higher than the costs of the river sanitation. Although this is encouraging, the authors correctly state that paying for polluting is not enough and steps should be taken to stop contaminating and to repair the damages caused during all the years when no river sanitation activities have been performed by the companies. This last point leads me to suggest for this study a complementary calculation which would consist precisely in valuing in economic terms the water that the companies have dumped into the river without treatment in the past 50 years, that is, what they have saved in their production costs. The next study devoted to the theme of protected agriculture is developed by Juan José Castellón Gómez. The author correctly suggests strengthening one of the strategic productive activities of the state of Tlaxcala, which is protected agriculture. His study directed at a design of intensive agriculture through advanced techniques can be complemented from the wealth of the broad and documented peasant knowledge present in the state of Tlaxcala. The work offers me the opportunity of glimpsing a synergy between state-of-the-art technology and traditional peasant knowledge, which would offer an unprecedented model for the Mexican countryside. To this, an additional strength may be added: for the model’s inputs to be organic, which would increase their nutritional value to supply markets inside the Zahuapan Basin. An additional element in favor of protected agriculture under this scheme would be its potential as a strategy for adaptation in face of the contingencies from climate change. The next chapter, written by Sergio Vargas Velázquez and Denise Soares Moraes, offers the description of the process of constitution of the Technical Committee on Underground Water in the Atoyac-Zahuapan (Comité Técnico de Aguas Subterráneas del Atoyac-Zahuapan). Something worth mentioning about this process is that it was framed by the approach of Integral Management of Water Resources, with a participative study which entailed the creation of Basin Councils, Basin Commissions, and Technical Committees of Underground Waters (Comités Técnicos de Aguas Subterráneas, COTAS), in order to involve the different social actors of the aquifer. However, as the authors themselves mention, water management has a strong stroke of centralism, with large voids prevailing for the implementation of actions at the local level. The authors describe that the process is from the top down, so that vertical relationships between the State and society are reinforced. The workshops for the constitution of the Atoyac-Zahuapan COTAS were performed with the methodology of project planning guided by objectives, better known as ZOPP for its initials in German. However, the authors mention that outside the activities from the ZOPP workshop no further actions have taken place, and more so given the discrepancies in interests between users from Tlaxcala and users from Puebla. Thus, an important task of being able to redesign the participant methodology of users from a diagnosis of actors and relationships between actors is still pending, in order to establish the best possible consensus and alliances based on this. This also implies an inescapable horizon of complex coordination not only at the level of aquifer users, but also between the three levels of government, the business sector, and the civil society organizations from the states of Tlaxcala and Puebla.

Finally, I consider that the book as a whole is quite valuable due to its production, since it contributes many elements for a future systemic diagnosis, where the contributions from so many specialists are interconnected. The book becomes a mandatory reference for future projects in planning, management and administration of the Zahuapan River basin.

As I mentioned at the beginning of my commentary, the greatest challenge that this 21^st century presents is the ability to imagine scenarios for sustainability. Imagination is the first step to change the current situation. Innovation schemes must be promoted in planning, where all the actors are fully represented and have the capacities for negotiations about legitimate interests. There should be recognition that all the inhabitants of the Zahuapan Basin, with the wealth of local ecological and cultural diversity, can achieve a common project. This challenge implies, without a doubt, the participation of local and state governments together with civil society, and within this, scholars are called to the challenge of doing research that goes beyond the interdisciplinary approach and enters the paths of what Ravetz and Funtowitz call post-normal sciences.