Aguas Informales
The History and Future Of Water In Mexico City
“God must think we’re crazy. We let the rain fall off of our roofs onto our soil; it washes the soil away and flows to the bottom of the hill. We then climb down the hill and carry it back up to drink.” — Unknown Ugandan Water Management Worker
In 1325, the Aztecs founded Tenochtitlan, their capital city, on an island in the middle of Lake Texcoco which was part of a series of connected lakes that used to occupy the Valley of Mexico. The city was connected to the mainland by a series of causeways, while all of its land was also broken up by a series of canals which allowed all portions of the early city to be accessed by land or water, on foot or in canoe. During the nearly two centuries that the Aztec capital prospered, it existed in tune with nature, respecting the environmental conditions that it inhabited. Due to the limited size of the city, though, the Aztecs had to become creative as the city grew on its island, a situation which informed and necessitated the development of the chinampa system, an agricultural strategy which allowed the Aztecs to begin to inhabit the water surrounding the island using ‘floating gardens.’
The chinampas were artificial islands created by fencing in areas of fertile soil with stakes and then planting trees along their edges to maintain the form over time and provide shade to the causeways and the islands themselves. These islands were then planted with crops and accessed for farming by canoe. This was an early innovation that allowed for the successful expansion of Tenochtitlan into the surrounding lake, and by 1521 when it was conquered by the Spanish, it had already become one of the world’s largest cities. This early growth coupled with the development of this innovative agricultural system was a precursor for the future of the city.
Unfortunately, though, after Tenochtitlan was conquered and the colonial city that would become Mexico City was established, expansion continued at unsustainable rates and the respect for nature that Aztec development had exemplified was largely lost. Since 1521 as the city has grown, the lakes which surrounded the city have rapidly been consumed, taken over, and filled in to the point where in modern Mexico City, the presence of the former lakes is almost nonexistent and the future of the city’s water supply is in question. This counter-intuitive condition illustrates the results of one of the major problems with contemporary urban growth. In a context where water supply should never have been a problem, the way that the city has grown has forced its citizens to consider this one of the major challenges facing Mexico City.
The Valley of Mexico is a major water basin which collects significant volumes of water from the surrounding mountains and which receives plenty of rainfall annually over a very large land area. Only a few centuries ago, much of this surface area was an enormous series of lakes, and yet today the urbanized valley surface has almost no surface water, and the underground aquifer has been almost entirely drained. As the city has struggled to make the supply meet the demand, significant infrastructure has been constructed to bring major volumes of water from the surrounding areas into the city. At the same time, though, the problem of drainage and wastewater removal has become an equally challenging concern; so, while immense efforts go into bringing water into the city, equal measures must be taken to later remove that water from the city after use. None of these systems work in cooperation with nature, in fact they are all fighting the natural systems of the land and the city’s hydrological conditions. Water is being forced in and out, in each case opposing the natural systems that would naturally have done both.
Although for the time being these systems are allowing Mexico City to continue to exist and even expand, there is no way that the current trajectory can be maintained: it is simply unsustainable. With Mexico City as an example, we can easily conclude that contemporary urbanization models are not sustainable, that currently, cities do not operate in harmony with nature, and it is with this understanding that urban planners, designers, developers, and architects must begin to plan for an urban future that respects the environment. This is true at the smaller scale of very basic private construction as well as at the much larger scale of urban infrastructural planning and development. And unfortunately, it is not enough to say that we must take these issues into consideration for future growth only, we must retroactively apply the principle of sustainable urbanism to the existing city and hope that we can reverse the damage that has already been done.
At the time that most modern cities were founded or established we did not possess this understanding, and in almost every example of extreme rapid urbanization over the past century there has been very little formal planning. The majority of contemporary urban growth occurs informally, often illegally, and often on marginal land that is either at a high risk for natural damage or is of a high ecological value. In either case, the consequences are significant for both the city and the land it depends on. It is difficult to imagine a solution to this phenomenon; however current trends cannot continue, strategies for more sustainable urban growth must be developed.
In the case of Mexico City, the specific solution must provide a framework for more sustainable growth while seeking to mitigate the environmental damage that has already been done over the past few centuries by urbanization completely indifferent to the present ecological conditions.
This solution requires returning to the aquatic origins of the city for direction and reintegrating a system of water bodies within the existing and future urbanism. This system of water bodies should be informed by the existing hydrological conditions of the valley basin, which is to say that although they must be reformed artificially, these water bodies will respect the ecological situation and require little artificial infrastructure to be maintained. In addition to reincorporating water into the city fabric this move would help promote urban revitalization along the edges of the newly reformed water bodies.
Mexico City is a heterogeneous mix of contradictions that cannot easily be reduced; however, as the city continues to experience rapid urban growth, the major challenges facing it are focused around water. With a population of nearly 20 million people, land that was once a series of lakes has been almost entirely transformed into a sprawling urban mass critically questioning the future of its water supply. As the population continues to rise and the city continues to expand, the demand on the water supply has increased dramatically. However, increasing demand is not the only problem. In recent years, the majority of urban growth has occurred informally, which means that the city is expanding onto land that is unsuitable for urbanization. With regards to the water supply, such expansion not only increases the strain on the existing ecology and municipal infrastructure, but threatens to further limit the city’s ability to supply its population with water. As the informal population grows, the percentage of the city without access to formal infrastructure increases rapidly, which forces many to seek alternative sources. These informal alternatives are often inadequate, unreliable, and more expensive than their formal counterparts. Fortunately, though, the city’s potential to collect rainwater offers a solution. Through an improved understanding of the city’s informal growth and its geographic and hydrological conditions, there is an opportunity to establish a framework for recharging the ground water supply and harvesting rainwater at the domestic scale. In addition, actions should be taken to reestablish surface water bodies in the form of a network of river corridors based on historic precedent. These interventions would begin to restore the water supply, while also providing a domestic solution which would enable the informal population to collect the water they need without relying on the municipality.
