Klavže - “Slovenian Pyramids”!

Hologram of Klavže on your phone

1. Fold the plastic pyramid. If needed, follow these instructions.
2. Attach the hologram pyramid on your smart phone.
3. Play the video in full screen. Enjoy!

Klavže, also known as water barriers, hold significant historical value as one of the well-preserved structures of the Idrija Mercury Mine.

Vojsko - Idrijske klavže

Water barriers on Idrijca river

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In the period from 1767 to 1813, five mighty stone water barriers were built on the Idrijca River, the Belca and Zala streams, and later in the valley of the Kanomljica stream. The klavže water barriers were used to accumulate water, which enabled the controlled floating of timber from Idrija's forests several times a year for the needs of the Idrija Mercury Mine and town of Idrija.

All the stone klavže, except for the klavže on the Zala stream, have been restored and can be visited. The restored klavže were inscribed as part of »Heritage of Mercury. Almadén and Idrija« in UNESCO's World Heritage List.

Photo: Arctur

The Idrija Mine was a huge consumer of wood throughout the entire period of its operation. In the beginning of the mine's operation, timber was delivered to the mine by means of natural floating, but this was only possible during heavy rainfall. Timber floated in this manner could last several months or even a year, during which the wood began to decay and lose its quality. Due to its dependence on precipitation, wood supply was irregular and insufficient. For this reason the Mine Administration decided to build initially wooden and later stone water barriers called klavže. These were used to regulate the irregular flow of the Idrijca River and its tributaries, thus enabling timber floating throughout the entire year.

Photo: Klavže; Photo Library of the Idrija Manicipal Museum.

The stone water barrier on the Idrijca River was built in 1772. Of all the water barriers, it had the largest capacity. The barrier of the Idrija klavže is 41.4 metres long and has a wall thickness of 10.8 metres in its upper part. When the gate was opened, up to 249,000 m3 of water flowed through both discharge channels from an almost 800 metre-long reservoir. In a single floating, the water carried up to 10,000 m3 of stacked wood down to Idrija.

Photo: Arctur

The stone water barriers were built according to the designs of Jožef Mrak a famous native of Idrija and the most notable Slovenian polytechnician of the 18th century, during the reign of Empress Maria Theresa from 1767-1772.

The construction of these stone water barriers is ranked among the top technical achievements of the 18th century.

Photo: Klavže. Historical Archives Ljubljana. Unit in Idrija.

At the end of the waterway in Idrija, the timber was stopped by a wooden rake called grablje.

The stone klavže are an outstanding monument to the Idrija Mine and its forestry. They tell us the story of the Mine's enormous need for wood, timber floating, construction of klavže, the first forest railway and cableway, the runner's path, the development of forest management in Idrija, restoration and caring for heritage.

Photo: Grablje; Photo Library of the Idrija Manicipal Museum.