The city of Montreal has ordered a moratorium on its plan to dump 8 billion litres of untreated waste water into the St. Lawrence River in mid-October.

Mayor Denis Coderre has requested a pause on the project of “a day or two,” executive committee chairman Pierre Desrochers said Wednesday morning, to ensure the best choices have been made after the issue received widespread attention in the media and the protests of opposition party Projet Montréal Tuesday.

“Chantal Rouleau (executive committee member responsible for water) has given all the reasons to show why this measure is justified,” Desrochers said during the city’s executive committee meeting Wednesday morning. “Nevertheless, at the demand of the mayor, to assure and as a question of diligence, the mayor has asked for a stop on this work and to look, over the coming days, to re-evaluate that the decision and the analysis that has been done is the right one, and to allow us to assure Montrealers of the need for the decision.”

Coderre was in New York City Wednesday for a conference on city security.

The city is planning to allow the untreated waste water to flow into the St. Lawrence River for seven days starting Oct. 18 to allow the construction of a new snow chute. The lowering of the Bonaventure Expressway during its reconstruction means a snow chute in place will no longer be able to be used to dispose of snow.

To build a new chute, workers need access to a sewer that would must be closed to allow them to work. The sewage water that usually flows through it will have to be redirected into the river for seven days.

That would mean dirty water from LaSalle, Lachine, Verdun, and Notre-Dame-de-Grâce heading into the river, at a rate of 13,000 litres of water a second, or 8 billion litres over the week starting Oct. 18.

It’s difficult to conceive that no measures could be implemented to prevent untreated waste water from being discharged directly into the river for a week

City spokesperson Philippe Sabourin said Tuesday the city has done the most it can to avoid the negative impacts, but there was no way around it.

Projet Montréal questioned the lack of alternatives Tuesday, saying there must be measures that could be taken to prevent sewage water from being discharged into the river for a week.

“We’re not questioning the construction of a new snow chute in the southwest, but it’s difficult to conceive that no measures could be implemented to prevent untreated waste water from being discharged directly into the river for a week,” Projet Montréal councillor Sylvain Ouellet said.

“Would it not have been possible to pump the waste water through a temporary detour to avoid the river being contaminated?” councillor Sylvain Ouellet said.

Sabourin said the city took the best solution it could, choosing a period when fish don’t spawn, and adding that the amount of untreated water that will be dumped into it is very small relative to the amount of water flowing in the St. Lawrence River.

He warned that people who usually surf on the continuous wave found behind Habitat 67 or who kayak in that part of the river should avoid doing so during the work.