Lakes gone, causeways remain

I marvel at the ways the ancient lakes of the Valley of Mexico play a role in contemporary life in Mexico City. 

At first glance at a map of the Valley of Mexico as it was in 1519, the year the Spanish conquerors arrived, reveals only one large, irregularly-shaped lake. But look closer and you’ll see six parts to it, each with its own name. That’s why it is proper to refer to them in plural, as the lakes of the Valley of Mexico.

Politically the most important of the six lakes was the Lake of Mexico. In the center of that lake lay the island of Tenochtitlan -- presently Mexico City's Historical Center.  It was there that Aztec priests saw an eagle perched on a cactus eating a serpent. They had been on the lookout for that sign, which their gods said would indicate where they should settle, since leaving their homeland in Aztlan in the thirteenth century. That sign is now on the shield of Mexico.

The Aztecs saw that sign in June of 1325 after fleeing from the area known as Culhuacan, near where the Taxqueña metro station is today. At that time Tenochtitlan was a swampy, snake-infested and difficult to access island. The Aztecs had little choice of where to settle and fewer friends. By 1325 no chieftain in the Valley of Mexico wanted to have anything to do with the Aztecs.  They were known as a powerful fighting force that won just about every battle they participated in. But they turned sides quickly. It all depended on who paid them the most.

With time and ingenuity the Aztecs solved the swampiness problem on Tenochtitlan by adding soil from the shore. They solved the snake infestation problem by acquiring a taste for them. This was so successful that they had to start importing them. They made the island more accessible by building earthen levy-type causeways to connect the island to the shore. Aztecs built dikes both for flood control and to regulate the salinity of the lakes to make them good for agriculture.  The lakes with the freshest water were used for "chinampa" farming. Instead of taking water to the fields as in contemporary irrigation, they took the fields to the water and built islands in the shallow lakes. 

Lake Texcoco, the largest of the six lakes, occupied the lowest elevation in the valley and hence was the saltiest.  Its salinity made it ideal for the production of spirulina, the topic of last week’s Charlie's Digs.  

Though all six lakes have mostly disappeared, Lake Texcoco still maintains a significant presence.  During take-off from the Benito Juarez airport look at the green and marshy area to the east and you’ll see the remnants of Lake Texcoco. Thankfully urban sprawl can't encroach on it because buildings would quickly sink into its very soft soil.

The lakes still determine how we travel through the Valley of Mexico.  Highways circle Lake Texcoco, and a toll road shoots right across Lake Texcoco from the aiport to the city of Texcoco.  My favorite way to return from Teotihuacan to Mexico City is on the toll road inaugurated within the last six years that skirts right along the northwestern shore of Lake Texcoco. You’ll see the wetlands of Lake Texcoco on the east side of the highway. An evening drive allows a view of the dark ancient lake and the city of Texcoco 15 kilometers away on the other side. 

Several of Mexico City's present-day thoroughfares follow the causeways the Aztecs built connecting the island of Tenochtitlan to the shores of the Lake of Mexico.  Of these, Viaducto Tlalpan is the most heavily traveled.  Though much wider now, it is the route Hernan Cortez chose when he entered Tenochtitlan for the first time in 1519. Two more Aztec causeways are under Avenida Hidalgo going west from the island of Tenochtitlan and under Calzada de los Misterios connecting Tlatelolco and the Basilica of Guadalupe. They all share the characteristic of being almost perfectly straight.  Understandable since they were originally built as earthen causeways crossing lakes. They were probably not even as wide as a lane of traffic today.

The ancient lakes also determine the route of Mexico City's grandest exspressway -- the Periferico.  It skirts along the southern and western shores of several of the lakes.  Last month I experienced driving on the Periferico's upper level for the first time.  Being an urban toll road it is touted as being lightly traveled; I now drive it every chance I get for its spectacular views of the innate beauty of this marvelous city.  Colonial church domes seem within arm's reach.  Long horizontal views of treetops are punctuated by Mexico's stunning high-rise architecture. Very different from aerial views in which we are looking down.  I like the views the best on the northbound drive.  That would have been the lake view when the lakes were visible -- surreal, tranquil views of this bustling crowded city.