The Idrijca 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...

 flowing through the Idrija Hills and Cerkno Hills

Cerkno hills

The Cerkno Hills is a transitional region between the alpine and the dinaric landscape centered around Cerkno, Slovenia. Several passes in this area connect the Poljane Valley and the Selca Valley with the Idrijca Valley and the Soča Valley. The highest peak is Porezen .The landscape is very...

. It is 60 km long. It rises near Vojsko, flows towards northeast and after passing through Idrija

Idrija

Idrija is a small town and municipality in the Goriška region of Slovenia. It is known for its mercury mine and lace....

 turns to the northwest. After passing through Spodnja Idrija

Spodnja Idrija

Spodnja Idrija is a settlement on the right bank of the river Idrijca in the Idrija Municipality in the Goriška region of Slovenia.The Parish Church in the settlement is dedicated to The Assumption of Mary and belongs to the Koper Diocese. It is locally known as the Church of Mary on the Rock . A...

 and Cerkno

Cerkno

Cerkno is a small town and a municipality in the Littoral region of Slovenia.It has around 2,000 inhabitants and is the administrative centre of the Cerkno hills...

 it joins the Soča

Soca

The Soča or Isonzo is a 140 km long river that flows through western Slovenia and northeastern Italy. An Alpine river in character, its source lies in the Trenta Valley in the Julian Alps in Slovenia, at an elevation of around 1,100 metres...

 in Most na Soči

Most na Soci

Most na Soči is a town in the Municipality of Tolmin in the Littoral region of Slovenia. It was named Sveta Lucija ob Soči until 1952. Other historical names include , and or Maurus Brucke. It is located on a rocky crest above the confluence of Soča and Idrijca rivers...

.

The river basin extends over 598 km². The major tributaries are the Belca, Zala, Cerknica, and Bača from the right and the Nikomlja, Kanošica, and Trebušica from the left. One of the right tributaries is also the Jezernica River, which originates from the Wild Lake

Wild Lake

The Wild Lake or Savage Lake is a lake near Idrija in Slovenia. The lake is also a karst spring and water flows from under the ground and through a steeply inclined tunnel. The tunnel has been explored to a depth of 160 metres. It is the source of Jezernica, a tributary of Idrijca and, at 55...

 . Being only 55 m long, the Jezernica is the shortest river in Slovenia.

The river has many fish, among which the Salmo marmoratus

Salmo marmoratus

Marble trout is a species of freshwater fish in the Salmonidae family, the second largest European trout species, second in size only to huchen...

, the Rainbow Trout

Rainbow trout

The rainbow trout is a species of salmonid native to tributaries of the Pacific Ocean in Asia and North America. The steelhead is a sea run rainbow trout usually returning to freshwater to spawn after 2 to 3 years at sea. In other words, rainbow trout and steelhead trout are the same species....

, and the Grayling

Grayling (genus)

Thymallus is a genus of freshwater fish in the salmon family of order Salmoniformes; it is the only genus of subfamily Thymallinae. The type species is T. thymallus, the grayling. The genus's five distinct species are generically called graylings, but without qualification this also refers...

 are noteworthy. In the past, timber was driven down the Idrijca to Idrija to be used as pillars in the Idrija mercury mine. Special logging sluices (Sln. klavže) were employed for this purpose from the 17th until the 19th century.

The area of the upper Idrijca has been proclaimed the Upper Idrijca Natural Park. It encompasses numerous karst features

Karst topography

Karst topography is a geologic formation shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite, but has also been documented for weathering resistant rocks like quartzite given the right conditions.Due to subterranean drainage, there...

 and diverse plant species. During World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 the Pavla partisan hospital stood there.

Tributaries

• Senčni potok
• Nikova
• Kanomljica
• Otuška
• Sevnica
  Sevnica
  Sevnica is a town and a municipality in central Slovenia.The town itself is situated on the left bank of the Sava River, and is one of the three major settlements in the Lower Sava Valley. The municipality is now included in the Lower Sava statistical region...
  
  
• Trebuščica
• Hotenja
• Črni potok
• Belca
  Belca
  Belca is a settlement in the Kranjska Gora municipality in the Upper Carniola region of Slovenia.- External links :*...
  
  
• Zala
  Zala
  Zala is the name of an administrative county in Hungary. Itlies in south-western Hungary. It is named after the Zala River. It shares borders with Croatia and Slovenia and the Hungarian counties Vas, Veszprém and Somogy. The capital of Zala county is Zalaegerszeg. Its area is 3784 km²...
  
  
• Ljubevšca
• Zaspana grapa
• Skavnica
• Peklenska graba
• Grda grapa
• Luknjica
• Zaganjalčnica
• Cerknica
  Cerknica
  Cerknica is a town and municipality in the Kras region of southwestern Slovenia, with a population of 10,284 . It belongs to the traditional region of Inner Carniola....
  
  
• Jesenica
• Bukovška grapa
• Žibernik
• Doberšček
• Bača
  Baca
  Baca may refer to:*Geovany Baca , Honduran boxer*Susana Baca , Afro-Peruvian singer*Bakkah, also transliterated Baca, is another name for Mecca, Saudi Arabia*Baca County*BACA, Bikers Against Child Abuse...