The Orne 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...

 in Normandy

Normandy

Normandy is a geographical region corresponding to the former Duchy of Normandy. It is in France.The continental territory covers 30,627 km² and forms the preponderant part of Normandy and roughly 5% of the territory of France. It is divided for administrative purposes into two régions:...

, within northwestern France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

. It discharges into the English Channel

English Channel

The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

 at the port of Ouistreham

Ouistreham

Ouistreham is a commune in the Calvados department' in the Basse-Normandie region in northwestern France.Ouistreham is a small port with fishing boats, leisure craft and a ferry-harbour. It serves as the port of the city of Caen. The town is about the mouth of the Canal de Caen à la...

. Its source is in Aunou-sur-Orne

Aunou-sur-Orne

Aunou-sur-Orne is a commune in the Orne department in north-western France.-History:In 1811 Aunou-sur-Orne absorbed the neighbouring commune of Saint-Cenery-près-Séez .-Famous people:...

, east of Sées

Sées

Sées is a commune in the Orne department in north-western France.It lies on the Orne River from its source and north-by-northeast of Alençon.-Name:...

. The Odon

Odon River

The Odon is a river in the Calvados department, in Normandy, northwestern France. It is 47 km long and is a left tributary of the Orne. The river passes through Jurques, Aunay-sur-Odon, Baron-sur-Odon, Bretteville-sur-Odon, Épinay-sur-Odon, Grainville-sur-Odon, Parfouru-sur-Odon, Tournay-sur-Odon...

 is one of its tributaries.

The Orne flows through the following departments and towns:

• Orne
  Orne
  Orne is a department in the northwest of France, named after the river Orne.- History :Orne is one of the original 83 departments created during the French Revolution, on March 4, 1790. It was created from parts of the former provinces of Normandy and Perche.- Geography :Orne is in the region of...
  
   (named after the river): Sées
  Sées
  Sées is a commune in the Orne department in north-western France.It lies on the Orne River from its source and north-by-northeast of Alençon.-Name:...
  
  , Argentan
  Argentan
  Argentan is a commune, and the seat of two cantons and of an arrondissement in the Orne department in north-western France.Argentan is located NE of Rennes, ENE of the Mont Saint-Michel, SE of Cherbourg, SSE of Caen, SW of Rouen and N of Le Mans....
  
  
• Calvados
  Calvados
  The French department of Calvados is part of the region of Basse-Normandie in Normandy. It takes its name from a cluster of rocks off the English Channel coast...
  
  : Thury-Harcourt
  Thury-Harcourt
  Thury-Harcourt is a French commune in the Calvados department in the Basse-Normandie region in northwestern France.Situated in the Orne valley, its surroundings are much like Clécy, but the Rock of Oëtre contrasts with the plateau of Caen to the north....
  
  , Caen
  Caen
  Caen is a commune in northwestern France. It is the prefecture of the Calvados department and the capital of the Basse-Normandie region. It is located inland from the English Channel....
  
  , Ouistreham
  Ouistreham
  Ouistreham is a commune in the Calvados department' in the Basse-Normandie region in northwestern France.Ouistreham is a small port with fishing boats, leisure craft and a ferry-harbour. It serves as the port of the city of Caen. The town is about the mouth of the Canal de Caen à la...
  
  

Hydrology and water quality

The waters of the Orne are typically moderately turbid and brown in colour. pH

PH

In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 levels of the Orne have been measured at 8.5 at the town of St. Andre sur Orne where summer water temperatures approximate 18 degrees Celsius

Celsius

Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...

. Electrical conductivity of the Orne has been measured at 30 micro-Siemens per centimeter.