Buried beneath Jerusalem: a massive First Temple dam

[Buster's Uncle]

Buried beneath Jerusalem: a massive First Temple dam and the ancient climate crisis that sparked it
JERUSALEM POST STAFF
Jerusalem Post
Tue, August 26, 2025 at 5:53 AM EDT
3 min read



The huge uncovered dam. (photo credit: Israel Antiquities Authority)


A mystery of ancient engineering revealed - was this the answer to Judah’s worst drought?

A study by the Israel Antiquities Authority and the Weizmann Institute of Science found that a climatic crisis led the kings of Judah to build a large dam wall in Jerusalem about 2,800 years ago, with high-precision dating placing its construction at 805–795 BCE and raising the question of whether King Joash or King Amaziah oversaw the project. The research was published in PNAS and was slated for presentation at the City of David Research Conference in early September under the theme The Lost Pool - The Mystery of the Siloam.

The dam, uncovered by the Israel Antiquities Authority at the Pool of Siloam in the City of David National Park, measured about 12 meters high, more than 8 meters wide, and 21 meters long. It was designed to collect floodwaters from the Tyropoeon Valley and the Gihon Spring, addressing both water shortages and heavy floods.

The structure joined two other water systems from the same period in the City of David: a tower that dammed the Gihon Spring and a large storage pit. From the tower, water flowed into a conduit that drained into the Siloam Pool, which also collected floodwaters blocked by the dam. Together, the dam, the channel from the Gihon Spring, and the Siloam Pool formed an urban water system in place by the end of the ninth century BCE.

Researchers paired the dating results with climatic data from Dead Sea drillings, Sorek Cave, and solar activity records, concluding that low precipitation and short, intense rain events characterized the period. They said the construction of large water systems responded to dry conditions and flash floods.

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Dr. Johanna Regev and Professor Elisabetta Boaretto of the Weizmann Institute used micro-archaeological methods and high-precision carbon-14 dating on construction materials. “In wood and short-lived young branches included in the construction mortar of the dam, a clear dating was found to the end of the 9th century BCE, with very high precision within a range of only about 10 years—an exceptional achievement in the research of dating ancient findings,” said Regev and Boaretto.

Itamar Barko, one of the dig managers, said the precise dating allowed definitive identification of the dam as the basis for the establishment of the Siloam Pool, which is mentioned in biblical and historical sources.

“The collaboration between the Weizmann Institute researchers and the Israel Antiquities Authority offers new insight into the challenges faced by the inhabitants of ancient Jerusalem. This massive royal construction project influenced the city’s development, particularly its southern and western parts - including Mount Zion - which relied on the waters of the Siloam Pool,” said Dr. Nahshon Szanton, an excavation director for the Israel Antiquities Authority.

“This is one of the most impressive and significant remains in Jerusalem from the First Temple period, which has been preserved at an exceptional level,” said Eli Eskosido, director of the Israel Antiquities Authority.

https://www.yahoo.com/news/articles/buried-beneath-jerusalem-massive-first-095344954.html