Kolbäcksån 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 Bergslagen

Bergslagen

Bergslagen is a historically, culturally, and linguistically distinct mining district located north of Lake Mälaren in northern Svealand, Sweden. In Bergslagen mining and metallurgic industry have been important since the Middle Ages...

 in the middle of Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

. It is about 180 kilometres long, arises in the province Dalarna

Dalarna

', English exonym: Dalecarlia, is a historical province or landskap in central Sweden. Another English language form established in literature is the Dales. Places involving the element Dalecarlia exist in the United States....

 and flows through the province of Västmanland

Västmanland

' is a historical Swedish province, or landskap, in middle Sweden. It borders Södermanland, Närke, Värmland, Dalarna and Uppland.The name comes from "West men", referring to the people west of Uppland, the core province of early Sweden.- Administration :...

 into the Mälaren

Mälaren

Lake Mälaren is the third-largest lake in Sweden, after Lakes Vänern and Vättern. Its area is 1,140 km² and its greatest depth is 64 m. Mälaren spans 120 kilometers from east to west...

. The river drains an area of approximately 3.100 km ² and has an average discharge

Discharge

Discharge in the context to expel or to "let go" may refer to:* A military discharge, issued when a member of the armed forces is released from service* Termination of employment, the end of an employee's duration with an employer...

 of 27 m³/sec. The city of Fagersta

Fagersta

Fagersta is a locality and the seat of Fagersta Municipality in Västmanland County, Sweden, with 10,890 inhabitants in 2005.- Geography :The city is located at the junction of two railways between Ludvika-Västerås and Avesta -Örebro, in the heart of the historic Bergslagen region which is rich in...

 lies on the river and the Strömsholm Canal

Strömsholm Canal

The Strömsholm Canal runs from Smedjebacken to Lake Mälaren near Strömsholm. It is 62 miles long with 26 locks. It consists of a string of lakes connected by short manmade cuts....

follows the river about 100 kilometres.