More than one hundred municipal wastewater systems did not report how much raw sewage overflowed from their pipes in 2017 but Environment Canada is only investigating two of them for violating federal regulations.

Environment and Climate Change Canada officials would not comment on the nature of those investigations since they are ongoing, including refusing to say which municipalities are involved or even what specifically the violations were.

Data provided to The Canadian Press recently showed over one trillion litres of raw sewage leaked into Canadian waterways between 2013 and 2017, including 215 billion litres in 2017 alone — a 10 per cent increase over 2013.

Environment officials attribute most the increase to more systems complying with reporting requirements. However Krystyn Tully, vice-president of the water advocacy organization Swim Drink Fish Canada, says only 159 of the 269 municipal systems that are required to report actually did in 2017.

"The compliance is so bad," said Tully.

She says the actual amount of leaking raw sewage is probably much higher than what has been reported, given that 110 systems were unaccounted for in the 2017 data alone.

Tully said governments are hard pressed to prioritize the problem if they don't know how much is actually leaking out of their systems.

Provinces 'need to prioritize these projects'

Environment Minister Catherine McKenna says the government isn't specifically looking at ways to improve reporting rates of municipalities but, if there is more to do, the federal government would consider it.

McKenna said Tuesday that climate change is expected to bring about more frequent storms, like the flash flood rainfall in Toronto a week ago that left the harbourfront waters covered in debris from the toilets of millions of Toronto residents.

"This is a real problem," McKenna said.

She said Ottawa has committed $2 billion to wastewater and water treatment infrastructure projects, cost-shared with provincial and municipal governments.

"Provinces need to prioritize these projects with cities but we are certainly there as a partner," she said. "I care greatly about the health of our waters."

Swim Drink Fish Canada, a water advocacy organization, says only 159 of the 269 municipal systems that are required to report their raw sewage leaks actually did in 2017. (Serge Bouchard/CBC)

Most cities only report calculated data based on computer models of how much sewage is expected to leak when a certain amount of rain falls. Kingston, Ont., is the only city Tully is aware of that has monitors in pipes to measure exactly how much leaks and reports that data publicly immediately.

Several cities are already taking steps to address the overflows of combined sewage and storm water pipes. Ottawa and Toronto are both building storage tunnels to prevent the systems from being overloaded during a storm. Toronto's $3 billion project will be built in phases with the first phase coming into operation around 2027, while Ottawa's $232.3 million project began in 2016 and is to be done in 2020.