Mexico City, a thriving metropolis of 20 million, is built on and around the ancient Aztec city of Tenochtitlan. Founded in 1325, this city was at its greatest a sophisticated and technologically-advanced city of 200,000 inhabitants nestled in the valley of Mexico and surrounded by a series of connected lakes.
The market district, Tlateloco was estimated by Spanish explorer Bernal Diaz del Castillo to be twice the size of Seville and bustling with over 60,000 shoppers and traders. The produce and goods for this market and several others in the city came mostly from the intricate and efficiently irrigated gardens created by the Aztecs in the shallow lakes surrounding the city. These gardens, called chinampas , were artificial island plots of 30 x 2.5-3 meters. These “floating gardens” produced 3 crops a year and grew at least a half to two-thirds of the food consumed by the 200,000 residents of Tenochtitlan.
Irrigated by the surrounding lake water, the chinampas were fertilized by digging up the nutrient-rich mud from the bottom of the canals and also by using human waste from the city itself. In this way, Tenochtitlan was able to better fertilize its crops while treating its wastewater― creating a healthier living environment for all. Crops were easily transported to market along the many canals and lakes surrounding the chinampas. When the Spaniards arrived it did not take them long to dimantle the complex system and put in place traditional monocropping. Today, some chinampas survive in the Xochimilo area close to Mexico City. They are cared for in the traditional way and create both food and an opportunity for a healthy tourist industry. Mexico city is currently trying to create a waste-water treatment system incorporating the use of chinampas similar to the ones used by the Aztecs so long ago.