The Bou Regreg is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 located in western Morocco

Morocco

Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

 which discharges to the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 between the cities of Rabat

Rabat

Rabat , is the capital and third largest city of the Kingdom of Morocco with a population of approximately 650,000...

 and Salé

Salé

Salé is a city in north-western Morocco, on the right bank of the Bou Regreg river, opposite the national capital Rabat, for which it serves as a commuter town...

. The estuary of this river is termed Wadi Sala.

The river is 240 kilometres long, with a tidal estuary

Estuary

An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

 of approximately 24 kilometres extending upriver. Its average discharge

Discharge (hydrology)

In hydrology, discharge is the volume rate of water flow, including any suspended solids , dissolved chemical species and/or biologic material , which is transported through a given cross-sectional area...

 is 23 m3/s and can reach 1500 m3/s during periods of flood

Flood

A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...

ing. The source

Source (river or stream)

The source or headwaters of a river or stream is the place from which the water in the river or stream originates.-Definition:There is no universally agreed upon definition for determining a stream's source...

 of the river originates from the Middle Atlas

Middle Atlas

The Middle Atlas is part of the Atlas mountain range lying in Morocco, a mountainous country with more than 100,000 km² or 15% of its landmass rising above 2,000 metres. The Middle Atlas is the northernmost of three Atlas Mountains chains that define a large plateaued basin extending eastward...

 mountains at an altitude

Altitude

Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...

 of 1627 meters on the level of Jbel Mtourzgane (Province of Khemisset

Khemisset

Khemisset is a city in Morocco, population 111,971 . It is situated on the A2 motorway between Rabat and Meknès , and is the capital of the province Zemmour....

) and of Grou (Province of Khénifra

Khenifra

Khenifra is a city in northern central Morocco, surrounded by the Atlas Mountains.-External links:*...

) and descends to its mouth at the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 separating the cities of Rabat to the south and Salé to the north.

Water quality

Water quality

Water quality

Water quality is the physical, chemical and biological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of standards against which...

 issues of the Bou Regreg include tidal saltwater intrusion

Saltwater intrusion

Saltwater intrusion is the movement of saline water into freshwater aquifers. Most often, it is caused by ground-water pumping from coastal wells, or from construction of navigation channels or oil field canals. The channels and canals provide conduits for salt water to be brought into fresh...

, excessive runoff

Surface runoff

Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...

 of nitrate

Nitrate

The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...

s from agricultural land uses and mercury

Mercury (element)

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

 contamination

Contamination

Contamination is the presence of a minor and unwanted constituent in material, physical body, natural environment, at a workplace, etc.-Specifics:"Contamination" also has more specific meanings in science:...

 thought to arise from use of certain pesticide

Pesticide

Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...

s within the drainage basin

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

.

History

The Phoenicia

Phoenicia

Phoenicia , was an ancient civilization in Canaan which covered most of the western, coastal part of the Fertile Crescent. Several major Phoenician cities were built on the coastline of the Mediterranean. It was an enterprising maritime trading culture that spread across the Mediterranean from 1550...

ns and the Carthaginians

Carthage

Carthage , implying it was a 'new Tyre') is a major urban centre that has existed for nearly 3,000 years on the Gulf of Tunis, developing from a Phoenician colony of the 1st millennium BC...

, 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

Chellah

Chellah, or Sala Colonia is a necropolis and complex of ancient Roman Mauretania Tingitana and medieval ruins at Rabat, Morocco. It is the most ancient human settlement on the mouth of the Bou Regreg River.-History:...

. This archaeological site contains the ruins

Ruins

Ruins are the remains of human-made architecture: structures that were once complete, as time went by, have fallen into a state of partial or complete disrepair, due to lack of maintenance or deliberate acts of destruction...

 of a Roman

Ancient Rome

Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

 town known as Sala Colonia and referred to as Sala by Ptolemy

Ptolemy

Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...

. Chellah was a significant ancient port city town with remains including the Decumanus Maximus

Decumanus Maximus

In Roman city planning, a decumanus was an east-west-oriented road in a Roman city, castra , or colonia. The main decumanus was the Decumanus Maximus, which normally connected the Porta Praetoria to the Porta Decumana .This name comes from the fact that the via decumana or decimana In Roman city...

, or principal way, as well as those of a forum, a monumental fountain, a triumphal arch, and other Roman ruins.