Longueuil is reminding residents to avoid contact with river water in the area east of the La Fontaine Tunnel as an eight-day-long release of raw sewage into the St. Lawrence begins.
Tap water is still fine to consume, but residents and businesses in the area are being advised to limit their water consumption until next Thursday.
By that time, the city estimates it will have dumped 162 million litres, the equivalent of about 65 Olympic-sized swimming pools, into the river.
The city says it has to, in order to repair a cracked pipe under the river between Île Charron and Old Longueuil — and since the fish spawning season is over and there is less activity on the river, this is the best time to do it.
There will be patrollers walking along the shoreline near the dump site, watching for pollutants and calling for mitigation measures as needed.
The city says it will also be testing the river water for contaminants at 20 different sites before, during and after the dump.