Now Norway's Public Roads Directorate will investigate the extent of the damage, newspaper Nationen reports.
"Most lakes that are near salted roads are more or less polluted by salt," Professor Johannes Kjensmo told Nationen.
Last winter 140,000 tons of salt were used on Norwegian roads, and the PRD is now so concerned that it has asked NIVA, the Norwegian Institute for Water Research, to study the matter.
The PRD has found that 1,000 lakes are less than 200 meters from a salted road or highway and NIVA has chosen 60 of these to test.
"We have chosen the lakes according to the amount of traffic on the nearest road, as well as the size of the lake," said NIVA water researcher Torleif Bækken.
The oxygen supply in the water is the most important factor to check. Most lakes undergo water circulation twice a year, in the spring and autumn. Water containing salt is heavier than fresh water and settles at the bottom.
"If there is a lot of 'heavy' salt water on the bottom of a lake it can hinder normal water circulation. In practice this will give oxygen-deprived, dead lakes," Bækken told Nationen.
