The Samarra Barrage (Arabic: سد سامَرّاء) is a multi-purpose barrage on the Tigris River adjacent (west) of Samarra and north of Baghdad, Iraq.

The main purpose of the dam is to divert floodwater in the Tigris River to Lake Tharthar through the Tharthar depression along with irrigation and an 84 MW hydro-electricity station.

Designs were completed by the British firm Voganlei and Coode.

The Samarra Barrage portion of the structure has 17 gates capable of passing 7,000 m3/s (247,203 cu ft/s) of water to the Tigris while the Tharthar regulator can divert up to 9,000 m3/s (317,832 cu ft/s) into a canal with 36 gates.

However, evaporation on Lakes Habbaniyah and Tharthar lead to reduced storage and high salinity, conditions unsuitable for irrigation.