The largest reservoir in the US has dipped to its lowest ever level, officials say, as an extreme drought continues in the region.<br />'' <br />''The surface elevation of Lake Mead along the Arizona-Nevada border fell to 1,071.56ft above sea level on Thursday.<br />'' <br />''It has sunk about 140ft since 2000 – which is almost the height of New York City's Statue of Liberty.<br />'' <br />''The reservoir is a major water supply source for more than 20 million people.<br />'' <br />''Among them are residents of such big cities as Los Angeles and Las Vegas.<br />'' <br />''Patti Aaron, a spokeswoman for the US Bureau of Reclamation, told media that the people are certainly concerned.<br />'' <br />''Lake Mead was created by the Hoover Dam in the 1930s.<br />'' <br />''Thousands of people were involved in the massive engineering project during the Great Depression, with more than 100 of them losing their lives.<br />'' <br />''Levels have been declining since 2000. Droughts have been getting worse in recent years, with scientists saying climate change is exacerbating the situation.<br />'' <br />''<span style="color: #222222;">The drought has for weeks been gripping several states in America's south-west, devastating farming in the region. </span><br />