When completed, Hoover Dam was called Boulder Dam, and then renamed for Herbert Hoover, the 31st president of the United States. An engineer and conservationist, he was a strong advocate for preserving natural resources and protecting public lands from abuse. He as particularly interested in destruction by disastrous floods. Always the engineer, he supported construction of a high concrete dam on the previously uncontrollable Colorado River to tame the river, and provide irrigation water to the rich farmlands nearby. Lake Mead, the reservoir created by Hoover Dam, became a dependable source of water for Southern California’s growing communities.