Floodgates are seen at the Rio Grande on Mexico's side in the border city of Ciudad Juarez December 13, 2007. Under a 1944 treaty, every five years Mexico is required to hand over water to the United States from the two dams the countries share on the Texas border. Historically, the Rio Grande, the fifth-longest river in the United States, flowed continuously from Colorado to the Gulf of Mexico. But since the 1900s, damming, channelization and over-exploitation have endangered its survival. To match feature MEXICO-USA/WATER. Picture taken December 13, 2007. REUTERS/Tomas Bravo (MEXICO)
REUTERS/TOMAS BRAVO