Sawa Lake (Arabic: بحيرة ساوة) was an endorheic basin located in the Iraqi governorate of Muthanna near to the Euphrates River, some 23 km (14 mi) to the west of Al-Samawa city.

Chemical and isotope analyses revealed its meteoric origin and a confirm a main feeding from the ascending groundwater from the lake bottom via joints, cracks, and fissure systems.

One kind of fish lives in Sawa Lake, the Arabian toothcarp of the genus Aphanius, Cyprinodontidatae family, characterized by its soft appearance, small size (they do not exceed 10 cm), and eyes that quickly disappear after death.

Also there are Pomatiopsis tryon which is Gastropoda genus and lives in brackish water from Oligocene age to recent times, particularly on the lake bottom.

The endemic race of little grebe (Tachybaptus ruficollis iraquensis) and the Mesopotamian crow (Corvus cornix capellanus) occur, as well as the near-endemic grey hypocolius.

The desert area on the western side of the lake, the fresh wetland strip (represented by the western branch of Euphrates River including the orchards), and the flat arid/semi-desert areas over the southern parts of the lake might harbor considerable wildlife diversity, mammals present include Rüppell's fox, striped hyena (near-threatened), honey badger, and Indian gray mongoose (Urva edwardsii).

[6] As Sawa Lake represents a unique, closed water body in Iraq it is an important site to protect for its scientific, educational and biodiversity value.