Valleyho Dam
From superman.nu: Supermanica
A great dam situated above the town of Valleyho, which “cracking under the strain of a huge downpour,†threatens to inundate the valley below it with a “great, irresistible flood of onrushing waterâ€, â€killing thousands and destroying the fertile landâ€, until the “weird figure†of Superman arrives on the scene to avert the “terrible disaster†and divert the raging “mountain of water†away from Valleyho (Act No. 5, Oct 1938). The story is reprinted in Superman No. 3 (S No 3/2, Win 1939).