Dams from the Beginning:

The earliest dams where remains have been found were built around 3000 b.c. for the town of Jawa in modern day Jordan. About 400 years later the Sadd Al-Kafara was built. It is estimated to have taken 10-15 years to build. The dam was built in ancient Egypt and was destroyed by heavy rainfall soon after its completion. It is assumed that primitive irrigation canals existed thousands of years ago, but no conclusive physical evidence has been found.