Chris Day - Environment Canada is launching its own investigation into a massive spill that dumped nearly one million cubic metres of sewage into the Ottawa River over a period of 15 days in the summer of 2006.

The federal probe will examine possible violations under Section 36 of the Fisheries Act.

"Our Government takes this matter very seriously and will use all the resources and authorities of the federal government to get to the bottom of what happened," Environment Minister John Baird said in a news release issued Thursday.

"As a lifelong resident of our city, I am obviously concerned about the potential negative environmental and health impacts that may have resulted from this incident," said Baird, who is currently in London, travelling with Prime Minister Stephen Harper.

The beach at Petrie Island, located in Ottawa's east end, was closed for 45 days in August 2006 after a valve malfunctioned upstream, spilling 900,000 cubic metres of biological waste into the Ottawa River.

Environment Canada's enforcement branch will now review the situation to try to determine whether federal laws were broken. There is no word yet on what penalties may be levied against the City of Ottawa, or individual city employees.

Ottawa mayor welcomes federal investigation

Ottawa Mayor Larry O'Brien welcomed the federal investigation, saying in a release: "I am confident we will achieve the thorough and rigorous examination required to determine the truth to this matter, while also restoring public faith in the process."

O'Brien also says the incident - and the delay in reporting it - highlights the need to change the "climate" at city hall.

"This is about accountability and creating an open and transparent government," he said.

"I am determined to bring about the appropriate governance changes that will eventually lead to a stronger, more effective and ultimately more accountable way of doing business in this city."

A city employee was fired Wednesday in connection with the sewage spill, which was not reported to the province until last May and kept from the public for almost two years.

The federal probe will coincide with three separate investigations into the spill.

The Ontario Ministry of the Environment and the City of Ottawa's auditor general Alain Lalonde have both launched their own investigations. Ottawa City Manager Kent Kirkpatrick is also looking into how the situation was handled and communicated through the appropriate chains of command.