A multi-university archaeology team led by the University of Cincinnati said the dam, constructed from cut stone, rubble and earth, was more than 260 feet long, stood about 33 feet high and held about 20 million gallons of water in a man-made reservoir.
It was one of several new landscaping and engineering feats uncovered at Tikal, a paramount urban center of the ancient Maya, a university release reported Monday.
The discoveries shed new light on how the Maya conserved and used their natural resources to support a populous, highly complex society for more than 1,500 years despite environmental challenges including periodic drought, the researchers said.
Water collection and storage were critical in the environment, where rainfall is seasonal and extended droughts not uncommon, the said.
"Their resource needs were great, but they used only stone-age tools and technology to develop a sophisticated, long-lasting management system in order to thrive," UC anthropologist Vernon Scarborough said. "So, they managed to sustain a populous, highly complex society for well over 1,500 years in a tropical ecology."