First Attempt at Draining of the Valley of Mexico

The Valley of Mexico is a closed basin that contained five interconnected lakes prior to the arrival of the Spaniards. As the Spaniards began development of present-day Mexico City, periodic flooding of the lakes threatened the urban development and the lifestyle of the citizens. Over multiple centuries, New Spain and later independent Mexico constructed various hydraulic works to reduce flooding and to increase the land area available for development and farming. These hydraulic works eventually led to the complete drainage of the Valley of Mexico. This study presents an engineering analysis of the first set of hydraulic works developed to reduce the inflow into Lake Zumpango, the most upstream lake in the northwest extent of the basin, which would reduce the overall flow into Lake Texcoco, the lake in which the capital city was built. The main hydraulic works included a 6.4-km-long tunnel, with a maximum depth of approximately 50 m, extending from Huehuetoca near the northwest border of the basin through the low hills forming the basin boundary; a 650-m-long open trench from the tunnel outlet to the Tula River; a 6.2-km-long canal from Lake Zumpango to the tunnel entrance at Huehuetoca; and a 25-km long diversion dam to redirect the Cuautitlan River to the newly constructed lagoon at the head of the canal at Lake Zumpango. The project was constructed in less than one year, using 60,000 indigenous laborers through a system of forced labor. Operation of the drainage project began in 1608, but faced a series of operational and maintenance challenges. The Heuhuetoca tunnel and maintenance of the other hydraulics works of the first drainage project were abandoned in 1623 when the cost of repairs and maintenance outweighed the benefit of the drainage system. This study also discusses the social inequalities interwoven in the drainage project.