In the United States, thousands of people in northern California have been asked to evacuate their homes after the tallest dam in the country was weakened by heavy rainfall. The California Department of Water Resources that the emergency spillway of the Oroville Dam could collapse at any moment. <br/><br/>Water levels in the reservoir have been rising because of heavy rain and snow in California following years of severe drought. The Department said that it is releasing as much as 100,000 cubic feet of water per second from the main spillway to try to drain the lake. <br/><br/>The combined population of the areas under evacuation is estimated to100,000 people. The dam built between 1962 and 1968, is the tallest dam in the United States.