The effects of the spill of nearly 5 billion gallons of wastewater into the St. Lawrence River appear to have been limited to the shores of Montreal, according to preliminary results of dozens of samples taken during the operation.
The samples made public yesterday show significant increases in the amount of fecal coliforms, but the situation seemed to reverse the day after the end of operations. The City of Montreal refuses to comment on the matter until next week, but already, these results provide insight into the impact of the spill.
The most affected banks
The numerous samples collected along the banks of the east of the island of Montreal show a strong increase in the amount of fecal coliforms during the spill.
The sample that demonstrated the strongest presence of these bacteria has also been taken after the Stephens Avenue in the borough of LaSalle. It has detected the presence of 2.7 million coliforms per 100 ml on the second day of the spill. This is well above the threshold of 1,000 coliforms per 100 ml at which contact with water is strongly discouraged by the Ministry of Environment.
The situation has however improved rapidly: the results observed in the same place Sunday, one day after the spill, corresponding to 2400 coliforms per 100 ml.
The waters of the Old Port still polluted
The various samples from the waters of the Old Port shows that this sector has been particularly affected by the spill. 39 coliforms per 100 ml the day before the operation, the rate rose to 22 000 in the third day.
It is also in the waters of the Old Port as coliforms rate remained higher after the end of the operation. On November 15, we still detected 14 000/100 ml. Note that two outfalls were located in this area.
Limited effect in the river
Samples taken at various points in the river suggest that the spill has had a limited effect near the banks, probably because of the dilution. Those taken in the middle of the river between Dickson Street in Montreal, and Roland-Therrien Boulevard in Longueuil, show that coliform levels remained low and stable (of 10-28 coliforms per 100 ml) at Along the spill.
A sample taken at the height of the tunnel-bridge Louis-Hippolyte-La Fontaine, however, shows that fecal coliform levels have risen to 570 per 100 ml on the fourth day of the spill. At this level, water sports involving contact with water are still allowed, but swimming is prohibited. Same results up to the Boucherville Islands.
The island of partially affected Sisters
The results of the sampling program demonstrate that Nuns’ Island was only partially affected by the spill.
Samples collected at the northern tip of the island indicate that fecal coliform levels were low before the gates open and climbed during the operation. The devices have detected 5400 coliforms per 100 ml of water at a time, or beyond the thresholds for contact with water by the Ministry of Environment.
Samples taken at the southern end, near the Maynard Ferguson Park, however, remained in standards throughout the spill: the rates ranged between 0 and 36 coliforms per 100 ml throughout the year.
Tests for Verchères islands
As a precaution, samples were taken at various locations to the Verchères islands located in the river about ten kilometers from Pointe-aux-Trembles.
Difficult to describe accurately the impact of the spill, since these points are located downstream of the discharge location used by the treatment plant wastewater Montreal. Some samples taken near Repentigny banks indicate that fecal coliform levels increased during the spill, while others, took over in the middle of the river, show that rates were high even before the operation.
No effects upstream
The samples collected upstream of the first discharge point located near the 1 st Avenue in LaSalle show that fecal coliform levels did not change significantly during the spill.
The results of these samples are indeed remained in the standards throughout the spill, ranging from 16 to 100 coliforms per 100 ml. These data suggest that, as expected, sewage did not back up the current and thus have no effect upstream of the spill.