Canadian Tire has admitted its stores have been charging consumers too much for eco fees since they came into effect on July 1. The company says it was the result of a computer glitch.

A receipt obtained by CTV Ottawa shows one Canadian Tire shopper was charged a 37-cent eco fee on a $1 jug of bleach. However, that charge should have been much less.

Examples listed in the Toronto Star on Wednesday indicate a shopper was charged a 60-cent eco fee on a $3 bottle of laundry detergent; another was charged a $3.23 eco fee on a $20 driveway sealer.

"We apologise to our customers for the inconvenience," said Canadian Tire spokesperson Amy Cole.

"Customers that return to the store with a receipt will be reimbursed the difference between the incorrect fee and the adjusted, correct fee."

Environment minister has serious concerns

In a letter to the head of Stewardship Ontario on Tuesday, Ontario's environment minister said he has "serious concerns" with overcharging of fees.

"Some retailers have been charging fees greater than the set fee Stewardship Ontario charges businesses. This is unacceptable and must be addressed immediately," said John Gerretsen.

"If the situation is not rectified, I will consider options to ensure consumers are not being misled about any fees being charged or eliminate altogether the ability to charge additional set fees to consumers."

What are the fees for?

The eco fees quietly came into effect on July 1, the same day as the Harmonized Sales Tax. The fees are applied to a long list of products, including aerosol containers, fire extinguishers, fluorescent tubes, syringes and needles, and all toxic, corrosive and flammable products.

The fees go to various stewardship councils across the province to ensure hazardous materials don't end up in landfills.

The Sierra Club of Canada says the program is important because hazardous material that isn't disposed of properly can become a health and environmental risk.

"Our water waste management systems aren't designed to capture those (hazardous materials) and process them out. (The systems) are about sanitizing, so they tend to go right through the system and end up in our drinking water, so we are drinking a watered down version of it," said John Bennett, executive director of the Sierra Club.

The first phase of eco fees were introduced on July 1, 2008. The Ontario government predicts the 13 new categories added to the program this month will help divert an estimated 26,000 tonnes of hazardous waste from the landfill in the first year alone.

Residents in Ottawa plan to protest the fee outside Premier Dalton McGuinty's office on Saturday.

With a report from CTV Ottawa's Catherine Lathem and Kate Eggins