|- location||Atlantic Ocean|
|Length||240 km (150 mi)|
The river is 240 kilometres long, with a tidal estuary going approximately 24 kilometres upriver. Its average discharge is 23 m3/s and can reach 1500 m3/s during floods. The source of the river is the Middle Atlas mountains at an altitude of 1627 meters on the level of Jbel Mtourzgane (Province of Khemisset) and of Grou (Province of Khénifra).
Water quality issues of the Bou Regreg include tidal saltwater intrusion, excessive runoff of nitrates from agricultural land uses and mercury contamination from use of some pesticides in the drainage basin.
The Phoenicians and the Carthaginians, who founded several colonies in Morocco, inhabited the banks of the Bou Regreg approximately two kilometers from its mouth at the ancient site of Chellah. This archaeological site contains the ruins of a Roman town known as Sala Colonia and referred to as Sala by Ptolemy. Chellah was a significant ancient port city with remains including the Decumanus Maximus, or principal roadway, as well as a forum, a monumental fountain, a triumphal arch, and other Roman ruins.
- Voyages and travels, Hakluyt Society, page 280 (1962)
- "Tarik Bahaj, Geochemical Characteristics of the Continental Waters Downstream from the Bou Regreg Basin and the Temara Plain, Morocco, October 30, 2007". Archived from the original on October 20, 2014. Retrieved August 21, 2017.
- C. Michael Hogan, Chellah, The Megalithic Portal, ed. A. Burnham, 2007