3. Review of events

The first step in the comprehensive review was to go over the events with all participants to establish an accurate chronology of the steps that led to the November 2015 discharge of untreated wastewater by the City of Montreal. This exercise resulted in a shared understanding of the sequence of events.

ECCC took into account all of the comments and the additional information provided throughout the process by the participants while maintaining the essential aspects of the analysis presented in the report.

Generally, all of the parties confirmed that they considered that the chronology established by ECCC matched the sequence of events. This detailed chronology is presented in Annex 3.

3.1 Highlights

From November 11 to 14, 2015, the City of Montreal discharged untreated wastewater into the St. Lawrence River so that the City could undertake major maintenance and construction work on its main sewer system. The temporary closure of the southeast interceptor was necessary to carry out maintenance on the interceptor and build a snow chute.

In order to decrease the volume of wastewater discharged and reduce the impact on the St. Lawrence River, the City of Montreal planned to carry out this work in such a way that there would only be one discharge of untreated wastewater. The City also ensured that the discharge took place at a time of year offering the most favourable hydraulic and environmental conditions, before the snow chutes were put in use, namely when the discharge would have the least impact on fish in the St. Lawrence and the people who use the river.

For the work carried out in fall 2015, the City of Montreal obtained a certificate of authorization from MDDELCC, as it had done for previous discharges. The City informed ECCC in advance of the planned work. Federal regulations do not provide for the authorization or issuance of a permit by the Department for a planned discharge of untreated municipal wastewater water of the type envisaged by the City of Montreal.

On October 16, 2015, the Minister of Environment Canada intervened by issuing a Ministerial Order under the Fisheries Act. The order delayed the work until November 2015 to give a group of independent experts the time to evaluate the City of Montreal’s plans.

On November 9, 2015, the Minister of ECCC issued a Ministerial Order based on the recommendations contained in the independent experts’ report. The order required the City of Montreal to make changes to the work and the monitoring procedures.

These conditions included monitoring measures and the participation of the City of Montreal in a comprehensive review process on the events that led to the discharge of untreated wastewater into the St. Lawrence River.