Question: What was the original name of the dam that serves as the northern boundary of the Topock Marsh?
Sentence (from "Hoover Dam"): Hoover Dam, originally known as Boulder Dam from 1933 to 1947, when it was officially renamed Hoover Dam by a joint resolution of Congress, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona.
Relevant evidence: Yes