Isaiah and Ahaz (7:1–9) Aqueduct of the Upper Pool (7:3). The existence of an “upper” pool, apparently outside the city walls to the north, suggests a lower one, which is also mentioned by Isaiah (22:9), perhaps within the walls and thus more secure during siege conditions. The aqueduct apparently carried water to the upper pool. Water was a major problem for Jerusalem throughout her history, and identification of the various elements of her water system is a matter of some debate.242 It appears