Montreal officials are moving forward with a controversial plan to dump eight billion litres of raw sewage into the St. Lawrence River.

The widely-criticized sewage dump was temporarily put on hold so the city could study alternatives. But officials said Friday that emptying a major sewer interceptor into the river is the only viable option that will allow necessary construction on the Bonaventure Expressway to be completed.

Beginning Oct. 18, a major sewer interceptor will be cleared into the St. Lawrence River over a period of seven to 10 days.

Quebec’s environment minister, David Heurtel, says the city has looked at all the options, but there is no choice but to go forward with the dump.

“We looked at the length of the work, we looked at the timing of when to do this, and we tried to work with the city understanding from their side there is no other way to do it,” Heurtel said on Saturday.

Officials have said the raw sewage will not affect drinking water, but residents are being asked to avoid coming in direct contact with the water on the southeast shores of the Island of Montreal and to avoid recreational activities like fishing during the dump.

Environmentalists say that during the dump, there will be 10 to 15 km of shoreline that people won’t be able to touch without running the risk of becoming ill.

Environment Canada has said it cannot authorize the sewage dump, but stopped short of saying whether it has the power to stop the city from proceeding.

In an email to CJAD news, Environment Canada spokesperson Mark Johnson said under the Wastewater Systems Effluent Regulations -- a set of rules that fall under the Fisheries Act and were enacted earlier this year -- the federal environment department "cannot authorize" the type of wastewater deposit Montreal is planning to undertake.

The Fisheries Act also prohibits unauthorized deposits of potentially harmful substances that can taint water where fish live.

Environmentalist and Green Party candidate Daniel Green says that “we might have people getting sick” and is not ruling out legal action.

“We are possibly looking at legal action to try and have this out before the discharge begins,” Green told CTV Montreal.

Quebec’s provincial environment ministry approved the plan earlier this year.

With a report from CTV Montreal