196 • The deaTh of azTec TenochTiTLan, The Life of mexico ciTy
some of the solutions that were proposed and carried out,
many of them with roots in indigenous experience.
The shoRTage of fReshwaTeR
As we saw in chapter 3, pre-Hispanic Tenochtitlan had
suffered acutely at times from a scarcity of freshwater, and
freshwater was always a valued resource. The project of
the Acuecuexco aqueduct under Ahuitzotl of 1499 tells us
that the densely populated city of that epoch needed more
water. Yet the city under Ahuitzotl’s successor, Moteuc-
zoma, seemed to function well enough just by using
Chapultepec water and by drawing on the springs that
existed within the city itself. So the lack of water resources
was not entirely crippling to the pre-Hispanic city, even
for the large populations of the first two decades of the
sixteenth century, when Tenochtitlan is estimated to have
had 150,000 residents. One reason was certainly the careful
husbanding of potable water; the city was largely supplied
by water sellers who delivered potable water by canoe, so
households had a limited supply of freshwater. And the
gradual desalinization of the laguna meant that canal water
from it could be used to nurture crops.
It was only after the Conquest that the problem of
freshwater scarcity escalated rapidly. This need is surprising
given the presumed overall drop in the city’s post-Conquest
population as the result of both the war and epidemic
diseases, a drop that should have diminished the demand
for water after 1521. But all evidence shows that it did not.
Why was this so? The unprecedented demands by new
Spanish residents on the water supply are well chronicled
in the Actas de cabildo: grants for orchards given along
the Tacuba causeway siphoned off needed potable water
for agricultural use even before it reached the city. And
the mills being constructed to grind wheat in and around
Tacuba, on the lake’s western edge, put another strain on
water resources. In addition, after freshwater coming over
the Tacuba causeway reached the entrance to the city at
the edge of Alameda park, it flowed into underground
pipes. City residents and institutions were given grants of
water from these pipes, allowing them a constant flow of
freshwater, a stark contrast to the parsimonious use that
canoe delivery encouraged. But another cause, less obvious
to Spanish observers, was having long-term and devastat-
ing consequences.
The breaching of the Nezahualcoyotl dike during
the wars of conquest and the subsequent neglect of the
Ahuitzotl dike meant that water resumed its natural flow
eastward, toward the salty Lake Tetzcoco. A drought
in the two decades following the Conquest reduced the
freshwater feeding the laguna, so the western side of the
city, where sweet water was once trapped in the laguna by
the system of dikes, began to dry out. Any backflow from
Lake Tetzcoco coming in during the rainy season would
have increased the salinity of these crucial wetlands. In
addition, the loss of forest cover of the surrounding hills
and mountains and resulting erosion in the slopes around
the valley silted up the laguna. 17 So overall, what had once
been a freshwater reservoir to the west of the city became
a shallow, salty swamp. Evidence for the drying out of
the western laguna in the mid-1530s comes from various
sources. During the second audiencia, when Bishop Sebas-
tián Ramírez de Fuenleal headed the government ( January
1531 to April 1535), the desiccated lake area around the city
emitted a foul odor, which was blamed for the outbreaks of
epidemic disease; the proposal of 1545 to fill in the laguna
and make it dry ground also indicates low water levels con-
tinuing through the 1540s. While indigenous agricultural-
ists, like those pictured in the Plano Parcial de la Ciudad
de México (figure 4.4), had reason to be concerned about
the dramatic loss of agricultural wetlands, Spanish lead-
ers were most concerned with maintaining sufficient canal
levels so that canoes could continue to move goods and
provision the city, which was made difficult when even the
canals that were cut into the lakebeds ran dry. Thus Span-
ish policies differed dramatically from earlier indigenous
ones. They wanted to fill the system from the north with
just enough water to help keep canoes afloat, a strategy that
helped to feed the salty Lake Tetzcoco but did little for the
wetlands of the laguna. Thus, so that canoe traffic could
move, Ramírez de Fuenleal requested that the waters of the
Cuauhtitlan river and waters from the Asumba (Otumba)
spring be allowed to freely flow into Lake Xaltocan. 18 Tw o
decades later, Viceroy Mendoza, in a similar vein, man-
dated that a canal be built so that the freshwater river
of Cuauhtitlan would be diverted farther north to Lake
Zumpango, thereby increasing the northern lake levels and
buoying canoes into Lake Tetzcoco, but not attending to
the sweet-salty balance. 19
As discussed in chapters 2 and 3, Tenochtitlan had
always been a marginal growing environment, given that a
salty lake originally surrounded it. But the construction of
the dikes transformed the waters in the Laguna of Mexico
by trapping the freshwaters flowing into the system from