The new power station at the Svelgfoss waterfall, near Notodden, would produce 30,000 horsepower equivalent to the total hydroelectric power production in Norway in the three previous years. It would be the largest in Europe at the time and the second largest in the world. The construction work, which was started in 1905, came to provide more than 400 jobs.

The Svelgfoss waterfall in Tinnelv river is just north of Notodden in Telemark, Southern Norway. Water flow was subject to significant natural fluctuations, and could fall to six cubic meters per second. However after the regulation of the lakes Tinnsjø and Møsvatn, Svelgfoss could be assured a minimum water flow of 90 cubic meters per second.

The regulation of Møsvatn alone was the largest regulation project in Europe at the time.

Test run

”The great waterfall can bellow away freely for the time being,” explained engineer Sigurd Kloumann to a local newspaper in September 1904, and another local newspaper wrote in May the same year that: ”The test run will decide whether the further plans will be realized. It is said that these involve no less than the harnessing of the Rjukan waterfall itself. There’s no shortage of power there”.

The regulation of Svelgfoss, Tinnsjø and Møsvatn were bold projects. If they proved successful, it would be easier to win support for even larger developments further up the watercourse.

The ground at the outlet of Tinnsjø lake was loose and uneven sand and clay to an unknown depth. The dam that was built was so solid that it did not need to be replaced for 95 years.

The Svelgfoss development was, however, more spectacular, and perhaps a more pioneering project. ”Time and time again the waterfall has made a laughing stock of our efforts, breaking up at night what we had built during the day, creeping through pores and cracks and dismantling a whole week’s work.”

Eyde was clearly very keen to get on with this project; so much so that he gave the go-ahead while he was still raising the financial backing.

”Most of the preliminary work was completed in the first half of December 1905, the time at which Hydro was constituted, and the foundations for the power plant and the main dam in the gorge were started at the same time. The further work on the power plant could now be continued on dry ground. The roof was finished in October 1906, and the work on installing the turbines started in 1907. The dam had been cast and  surface treated by the end of March 1907, and in October the same year the power plant started production,” Eyde writes in his memoirs.

”They had to fight against the waterfall”

”It was a roaring witch’s cauldron of a waterfall in which they had to dig, lay stones and construct. Every single tool, every piece of machinery had to be transported by cable over the gorge; the whole power plant that you now see sitting snugly at the bottom was lowered by crane one piece at a time. Day by day, inch by inch, engineers and workmen have fought against the waterfall, subjugated its force and put it in chains, while tunnels were dug and the dam built up.”

When the Notodden factories were completed in 1907, they had 30,000 horsepower from Svelgfoss to put to use. The power plant later increased its capacity by 10,000 horsepower, and an additional 15,000 horsepower was added from the development of the Lienfoss waterfall further down the watercourse.

These power plants became an attraction, and were visited regularly by ”important men” from both Norway and other countries. King Haakon VII of Norway visited in 1908 and 1909, and King Chulalongkorn of Siam arrived in the summer of 1907, and looked around both Notodden and Rjukan.