MONTREAL - An environmental group asserts that the federal government greatly underestimates the amount of greenhouse gas emissions that are produced by hydro electric facilities.

A report issued by the Global Forest Watch concludes that the difference between emissions produced by fossil fuels and hydro electricity is not as great as was previously thought.

Spokesman Peter Lee said that the study generally accepts the Canadian government scientific data but asserts there is a range of other scientific data that demonstrates that the total emissions produced by hydro electricity is much higher than the government states.

Hydro electricity produces greenhouse gas emissions when trees and other plants are submerged during the creation of reservoirs.

Carbon is released into the atmosphere as these organic materials gradually decompose.

The federal government has estimated, using a methodology proposed by the Intergovernmental Panel on Climate Change (IPCC), that such emissions amount to 0.5 megatonnes of carbon dioxide each year in Canada.

The study concludes that the real quantity of hydro electric greenhouse gas emissions is between seven and 13 megatonness of carbon dioxide. Most of these greenhouse gases are emitted in Quebec.