The Dragon Mining company has been pumping water into the lake in order to keep the mine dry for as long as the mine has been operational.
The gold mine is currently seeking an environmental permit for mining operations to continue. The environmental study required for the permit found significantly elevated concentrations of sulfates, nitrogen and metals in the drainage water. Sulfates and metals can be traced back to mineral ores, while nitrogen originates from the extraction process.
The study relates to the Ala-Jalkajärvi and Peräjärvi lakes – the latter receiving flow-on from the former.
According to Dragon Mining’s CEO, Heimo Pöyry, the decontamination plan will be made by the same company who managed the assessment of the lake, Kokemäki’s waterway conservation association (Kokemäenjoen vesistön vesiensuojeluyhdistys ry).
Pöyry claims that after the plan gets the green light from local officials the company will proceed to take necessary actions to improve the water quality.
Watercourse decontamination work is not expected to commence until 2014, according to the Kokemäki waterway conservation association.