Longyearbyen in Svalbard has been told not to drink tap water after thawing permafrost and local shale bedrock leached heavy metals into its main supply from the 2.5 km dammed lake Isdammen. Tests last September found manganese levels 25 times higher than the 50 micrograms per litre recommended by the Norwegian Institute of Public Health, and earlier this year sulphate and nickel also exceeded drinking-water limits. Permafrost expert Marjolaine Verret said thawing plus pyrite-bearing shale is producing acid that mobilises metals; prolonged high manganese exposure can cause neurological problems in children and infants. The municipality of Longyearbyen, which has about 2,600 residents, deployed emergency measures including a central tank of purified water filtered by the local brewery for residents to refill containers. Mayor Terje Aunevik said manganese had “gone ballistic” and has commissioned an investigation while warning that government guidelines require the ban to remain. Officials are considering a completely new water mains supply, installing filtration on Isdammen, or building a desalination plant as backups, but said all options are technically difficult and extremely expensive in Svalbard's conditions. Scientists have flagged this episode as a warning for other Arctic communities with similar geology and warming permafrost.
