Norwegian hydropower producers are cutting output in southern Norway this summer to save water for the winter, fearing a looming supply crunch after a prolonged period of dry weather diminished reservoir levels.

There is also concern that hydropower, which accounts for around 90% of Norwegian electricity generation, will continue to be exported to continental Europe.

The reservoirs feeding many of the plants are currently only 59% full, compared with a 20-year median level of 68%, according to data from energy regulator NVE.