Archaeologists Unearth Israel’s Largest Ancient Dam in City of David

Israeli archaeologists have uncovered a groundbreaking piece of national heritage: the largest ancient dam ever discovered in Israel, located at the Siloam Pool within Jerusalem’s City of David National Park. This monumental structure, dating back nearly 2,800 years, offers powerful new insight into how ancient Jerusalem’s leaders adapted to environmental threats with engineering brilliance.

A joint study by the Israel Antiquities Authority and the Weizmann Institute of Science has dated the dam’s construction to the reigns of King Joash or King Amaziah of Judah (circa 805–795 BCE). The massive dam, which stretches over 21 meters long, 12 meters high, and more than 8 meters wide, still extends beyond the current excavation zone a testament to its colossal scale and importance.

“This is the largest dam ever discovered in Israel, and the earliest found in Jerusalem,” said excavation directors Dr. Nahshon Szanton, Itamar Berko, and Dr. Filip Vukosavović. “It was a dual-purpose solution collecting water from the Gihon Spring and diverting flash floods from the Tyropoeon Valley to the Kidron Stream.”

The researchers believe the dam was constructed in direct response to a severe climate crisis, revealed through advanced analysis by Weizmann Institute experts Dr. Johanna Regev and Prof. Elisabetta Boaretto. Using radiocarbon dating of short-lived organic material embedded in the mortar, scientists were able to date the construction to within a decade a rare level of precision in archaeological research.

By correlating this data with climate records from Dead Sea sediment cores, Soreq Cave formations, and solar activity patterns, the team concluded that Jerusalem’s rulers were responding to a period of drought punctuated by violent storms. Their answer? A royal-scale waterworks project that fed growth in the city’s southern and western regions, including Mount Zion.

This discovery joins two other major waterworks from the First Temple period a fortified tower protecting the Gihon Spring and a sophisticated water channel system leading to the Siloam Pool. Together, they form a complex urban water management network built centuries before the Babylonian exile, revealing a Jerusalem that was not only spiritually central, but technologically advanced.

Eli Escusido, Director of the Israel Antiquities Authority, called the find “one of the most impressive and significant First Temple-period remains in Jerusalem.” Heritage Minister Rabbi Amichai Eliyahu added: “This dam is tangible proof of the strength of the Kingdom of Judah and the ingenuity of its kings in the face of natural threats.”

He concluded, “Nearly 3,000 years ago, Jerusalem’s residents were already applying advanced engineering solutions to a climate crisis. This fusion of exact sciences with archaeology provides new, indisputable insight into our nation’s history.”

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