Gatineau currently tracks the number of times raw sewage is dumped into the Ottawa River but not how much sewage is being dumped. (CBC)

The City of Gatineau wants to find out how much raw sewage it is flushing into the Ottawa River.

The city issued a call for tender Tuesday seeking the services of a company that can collect and provide such data.

Louise Lavoie, the city's director of environmental services, said Wednesday that Gatineau needs the numbers because it wants to take measures to reduce its sewage overflows. Those measures could cost millions of dollars, so the city needs to know what type of intervention will have the greatest impact and be the most cost effective.

Both Ottawa and Gatineau have combined sanitary and storm sewers that can get filled to capacity during heavy rains. During those times, the wastewater systems are designed to dump the excess raw sewage into the Ottawa River.

"It's recognizable as sewage, and it just looks like dirty water with things floating in it, and you could recognize some components that you probably wouldn't want to talk about," said Meredith Brown, a member of the river conservation organization Ottawa Riverkeeper.

The sewage can contaminate the water with E. coli bacteria, forcing beaches along the river to close.

While the City of Ottawa tracks both how often its sewage overflows into the Ottawa River during heavy rains and the amount of the overflow, Gatineau currently only tracks the number of overflow events and not the quantity of sewage involved.

Even with the new data, it will be hard to compare which city dumps more sewage, Lavoie said. That's because Ottawa has only a few, larger sewage overflow sites while Gatineau has about a hundred that spill smaller amounts of sewage.

Ottawa city councillor Peter Hume, who represents the Alta Vista ward, welcomed Gatineau's move, nonetheless, saying any additional data would be helpful in solving the joint problems faced by Ottawa and Gatineau concerning the river between them.

Brown said such monitoring is very important. "How can you fix a problem if you don't know how much of a problem it is?" she asked.

She added that Gatineau needs a new sewage treatment plant, and she hopes that like Ottawa, it will adopt the goal of ultimately eliminating raw sewage overflows.