River flotation was once the main method of transportation of timber logs from the forests down to the saw mills and paper mills, typically located by the coast. In Sweden, where timber and paper has been major export products since the early days of industrialization, log driving started in large scale around 1880. Most river systems in the mid- and northern parts of the country were extensively used for this purpose, but as giant hydro-power dams were being built from around 1910 and onward, an accelerating conflict grew between the power producers and the logging companies. However, back in these days, the vertically integrated companies often owned both forests, saw mills, paper mills and the hydro-power plants, so the conflicts were more of an internal nature.
Obstacles in the rivers, such as waterfalls and rapids caused major problems for the flotation as the logs packed and jammed the river. Apart from very brutal means of blasting rocks, dredging and removing obstacles, fixed piers and box-booms were built, generally causing large damage to the fish and river ecosystems. At the most difficult passages, log flumes were built to get the timber around the obstacle. Flumes were also the standard way to bypass hydropower dams, but the power companies saw valuable water being spilled through the flotation dam gates. As the vertically integrated companies were broken up and the power producing parts were sold out, one can guess that the new owners did what they could to get rid of the flotation.
This particular log flume was completed around 1900 to bypass a series of rapids in river Dalälven and to get the logs directly into the recently extended saw mill at Bomhus. A new sulphite mill was opened in 1910, just adjacent to the saw mill and the timber requirements increased steadily. Furthermore, one can guess that as a series of hydropower dams were projected in the river, it was a wise decision. The first 70 MW hydropower plant opened in 1915 and more followed in the year to come. The log flume was rebuilt and modernized in the 1950s and had then an overall length in excess of 30 km (18.6 miles). In the 1960s, some 10 million logs were transported this route annually. When the flotation in river Dalälven ended in 1970, the log flume was converted to carry non-salty process water to the Korsnäs paper mill. This seems to have ceased quite some years ago, probably due to a more efficient and closed-loop system for process water in the paper mills being standard nowadays.
Today, the route is in a late stage of decay and at first sight it seems highly unlikely that it will ever be used again for any purpose. It however appears like it is still used for water supply to the lake Älgsjön and the Korsnäs mill, at least sporadically. Given its impressing length and solid construction, it is a spectacular installation to watch. Presumably, there is no sense of urgency to demolish it, given that it goes out in the middle of nowhere. Another guess is that the vast amount of plank originating from the 1950s are impregnated with some pretty nasty chemicals and probably the cost of sending that for destruction could exceed the cost for the demolition itself. The concrete foundation will probably stand to the next ice age, but the all-wood flume itself, is obviously deteriorating quicker. Although the plank dimensions are impressing, it feels quite swampy and it will probably start to fall apart in a near future.