In September, 100,000 litres of diesel leaked from one of the utility's pipelines in the Magdalen Islands.
The public utility expects to spend $20 million on the cleanup, and while it does have insurance to cover oil spills, it's only covered for accidents that cost between $50 and $900 million.
Serge Abergel, a spokesperson for Hydro-Québec, said the cleanup is part of the utility's maintenance costs and it's up to consumers to foot the bill.
"The rates reflect the cost incurred to provide electricity service, and by those costs I mean, all the costs including investments, and operations, of the distribution network, in order to supply power to customers," Abergel said.
"So once you have a problem with one of your installations, or a pipeline as was the case here, it's considered a part of the cost related to operations of the distribution network."
Hydro-Québec will ask the energy board if it can include the cost of the cleanup in its upcoming rate increase, Abergel said.
Abergel couldn't give an exact figure, but said the cost would be divided amongst its customers. The public utility has more than four million customers.
Marc-Olivier Moisan Plante, an energy analyst with the Union des Consommateurs, a consumer rights group, said his organization will recommend the energy board reject the utility's rate increase demand.
"If the customers pay for Hydro-Québec spillovers every time, there's no incentive for Hydro-Québec to maintain a safe power plant and good environmental practices," he said.