Siloam dam dated to reign of Jehoash?

MONUMENTAL ARCHITECTURE: Biblical Kings in Jerusalem May Have Built Monumental Dam to Deal With Climate Change. A controversial dig in the City of David uncovers a First Temple Period dam. Researchers link the 2,800-year-old structure to efforts to face increased drought and flash floods (Ariel David, Haaretz).

The dam is only the latest in a slew of recent discoveries in Jerusalem that can be linked to this part of the First Temple Period, and attest to a time of early expansion of the city at the turn of the 9th-8th century B.C.E., possibly under the rule of King Jehoash. Specifically, the construction of the dam may have been triggered by a greater need to store and control Jerusalem's key water supply in a time of climate change that brought longer dry periods, the researchers speculate.

The article links to the underlying open-access artice just published in PNAS:

Radiocarbon dating of Jerusalem’s Siloam Dam links climate data and major waterworks

Johanna Regev https://orcid.org/0000-0002-2171-7452 johanna.regev@gmail.com, Nahshon Szanton, Filip Vukosavović, Itamar Berko, Yiftah Shalev https://orcid.org/0000-0003-4969-531X, Joe Uziel https://orcid.org/0000-0001-9795-3980, Eugenia Mintz, Lior Regev https://orcid.org/0000-0002-5558-4117, and Elisabetta Boaretto https://orcid.org/0000-0002-8320-6228 elisabetta.boaretto@weizmann.ac.il
Edited by Melinda Zeder, Smithsonian National Museum of Natural History, Washington, DC; received April 29, 2025; accepted July 9, 2025
August 25, 2025 122 (35) e2510396122 https://doi.org/10.1073/pnas.2510396122

Abstract

Using well-established microarchaeological sampling methods, we reached a precise radiocarbon date of 800 BC for the Siloam Pool’s monumental water dam in Jerusalem. This date is a critical link connecting several imposing waterworks constructed at that time. Climate data pointing to droughts and flash floods during the last decades of the 9th century BC provide a logical framework for the reasons behind such endeavors. These included the fortification of the city’s primary water source, the Gihon Spring, and the redirection of the water into the city through a channel to an artificial reservoir created by building the Siloam Dam at the end of the Tyropoeon Valley, which blocked the drainage of rain and redirected spring waters.

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