A Russian court Monday sentenced a former mayor to six months of community service after finding him guilty of criminal negligence due to a major diesel fuel leak from a storage tank in the Arctic city of Norilsk in May. 

In a statement, the Krasnoyarsk Regional Court announced that Riant Akhmetshin was sentenced to “correctional labor for [six] months with a deduction of 15% of wages” for committing a crime under Part 1, Article 293 of the Criminal Code of the Russian Federation.

Norilsk, an industrial city within the Arctic Circle with a population of 175,000, is home to the largest known nickel-copper-palladium deposits in the world. The city is built around the Nornickel company, the world’s largest producer of nickel and palladium.

The Norilsk disaster caused roughly 21,000 metric tons of diesel to flood into local rivers. Russia’s natural resources regulatory agency reported that bodies of water more than 20 kilometers from the spill site contained concentrations of petroleum contaminants that were “tens of thousands of times from the norm.”

Russian President Vladimir Putin scrutinized regional leaders for their slow response to the spill after they initially claimed that there was no significant environmental damage. A state of emergency had been declared in June, and Akhmetshin resigned as mayor in late July.

Greenpeace likened the accident to the Exxon Valdez oil spill, which occurred 30 years ago off the Alaskan coast. In June, Greenpeace estimated that the “ecological damage to bodies of water in the affected region alone could exceed six billion rubles (US$86.3 million).”