The Lubicon Lake First Nation says Pennwest (TSX:PWT) believes the spill took place on Saturday evening in an area that is the proposed location of future reserve lands.
It says the company initially said the spill affected surface waters and muskeg lands over 2.5 square kilometres.
But Lubicon Lake says the spill is now thought to be larger than initial estimates.
Pennwest is working to contain the spill but says the flooding in Calgary is having a negative effect on the management of the spill, particularly when it comes to communications.
Lubicon Lake Chief Bernard Ominayak says the safety of the first nation's citizens and their environment is the "primary concern."
Lubicon Lake spokesman Garrett Tomlinson says the spill is about 25 kilometres from Little Buffalo, where most of the first nation's residents live, but the oil spill is a big concern for hunters and trappers in the areas affected by the leaked oil.
He says the company still doesn't know if heavy rain in the area contributed in any way to the spill.
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