Brisbane and Sydney's prewar dams and reservoirs were not sufficient to provide reticulated water to the hundreds of thousands of new households that settled in rapidly growing suburbs from the early 1950s. Following American precedent, large concrete gravity dams became easier to build. Hydrologists predicted the likely volume that catchments and valleys could both collect and hold if dammed. This article examines the decision-making trajectory of the two largest potable water urban dams in Australia, Warragamba and Wivenhoe, from conception and construction to operation. Per capita consumption of water rose sharply in the 1980s but subsequent droughts have forced both governments and the populace to change the way they use water and no longer imagine that supply is unlimited.

布里斯班和悉尼战前的水坝和水库不足以为1950年代初开始在快速发展的郊区定居的数十万新家庭提供网状水。遵循美国的先例，大型混凝土重力坝变得更容易建造。水文学家预测，如果大坝蓄积，流域和山谷可能会收集和容纳的水量。本文研究了澳大利亚的两个最大的城市饮用水大坝Warragamba和Wivenhoe的决策轨迹，从构思，建造到运营。人均用水量在1980年代急剧上升，但随后的干旱迫使政府和民众改变了用水方式，不再想象供水是无限的。