HELSINKI, March 12 (Reuters) - Uranium that leaked from Talvivaara's nickel mine in eastern Finland last November has been found in high concentrations at the bottom of nearby lakes, potentially increasing clean-up costs for the miner.
Finland's nuclear safety authority, STUK, said water samples taken last week from lake Salminen, near the Sotkamo mine, showed uranium levels six times higher than the advised level for drinking water.
The Talvivaara disaster has dominated headlines in Finland. The country's many lakes are interconnected, meaning pollution in one lake can flow into rivers and lakes downstream.
Authorities said the levels of uranium in waters near the mine had decreased since the leak but the latest data suggested there still was a heavy concentration of pollution in some lakes near the mine.
STUK director Tarja Ikaheimonen said the uranium-affected water could begin flowing downstream in the spring as snow and ice begin to melt, while adding it would not pose a significant threat to public health.
"I think these waters belong to the waters that need to be cleaned," Ikaheimonen said.
Talvivaara said it expected the uranium and other leaked metals to remain settled at the bottom of the lake, although it would consider the need for purification.
It is currently draining cleaned excess waters from the mine in an attempt to be able to restart mining and crushing operations.
"Of course we will proceed based on requirements set by STUK. We have not yet received a demand to pump away or clean the water," Talvivaara's environmental manager Veli-Matti Hilla said.
Last Friday Talvivaara's shareholders agreed to stump up 261 million euros ($340 million) through a new share issue to keep the mine running.