Originally constructed in 1852, the Presa de San Renovato (Saint Renovate Dam) was a pragmatic structure meant to reinforce the water-holding capabilities of the older Presa de la Olla (Clay Pot Dam).

Both were designed to control the water levels of several springs and little rivers that flow from the surrounding hills (La Bufa chief among them), and placed the city in danger. On one side, the springs and rivers often ran dry, resulting in major droughts. On the other, water levels would rise dramatically and lead to floods, such as the floods of 1760 and 1905. The 1905 flood occurred despite both dams being in place. 

A redesign of San Renovato during the early 20th century Porfiriate period beautified the dam. Walls were painted red and featured tiles designed by artist Manuel Leal. An inland lighthouse was built on Bufa Hill and the lower river embankment was transformed into a sunken garden. Located in the garden are two larger-than-life sculptures depicting a snake and an alligator.

In typical Guanajuato fashion, these creatures represent a local legend. It's believed that two neighbors would race each other daily to be the first to fill their clay pots with water. Their confrontation escalated one morning and they broke each other's pots. Both fell into the river during the struggle and were forever cursed. The curse transformed them into the two sculptures visitors see today.