Foreword Beside the Statue of Liberty and Golden Gate bridge, United State of America has another structure which show the face of the USA industrial power in early 20th century; the Hoover dam. People are already known a lot of the advantages of the great Hoover dam, but the disadvantages of Hoover dam, special in negative effects on environment, are not popular at all. People must understand that hydraulic structures such as Hoover dam are not as good as people thought. Therefore, now we need a research about the negative effects of Hoover dam on environment so that we can come to the balance of economy and environment in future hydraulic structures. 1