The Medjerda River rises in Algeria and flows east through the third of the country with reliable rivers, the north. It empties into the Gulf of Tunis and Lake of Tunis. At it is the longest river. It is also known as the wādi (or ) Majardah and Wadi Mejerha and it was known as Bagrada in ancient times. It rises in a further section of the Tell Atlas in Algeria, staying to the south of the Tell escarpment while within the country. It has been dammed at the Sidi Salem Dam. The Oued Zouara rises in the country's own section of the Tell. It has been dammed by the Sidi el Barrak Dam which forms a large lake widely used across the north and centre of the country in an advanced water management project.