Why does the lake level fluctuate?

It is normal for water levels at Amistad Reservoir to fluctuate. The reservoir is a man-made pool created to store water and prevent flooding. From 1992-2002, the reservoir dropped and remained low during an extended drought. A tropical storm system in 2003-2004 brought increased rain to southwest Texas and by 2005, the lake was near the conservation pool level of 1117 feet above mean sea level. Water continues to be released from Amistad Dam to provide for municipal use and irrigation for communities downstream along the Rio Grande.