01/19/2015 07:32 EST | Updated 03/21/2015 05:59 EDT

St. Lawrence River: 334 spills in ten years

The 28,000 litres of diesel that spewed into the St. Lawrence River last week — and led to a municipal drinking water advisory in Longueuil — is just the latest in a long list of oil spills into the river. 

There were 334 spills involving ships in the St. Lawrence River between February 2002 and November 2012, according to federal documents obtained by Radio-Canada. 

The documents also show the limits of the system used by the federal and provincial governments to track the extent of spills and their potential environmental impact. 

Most of the cases involved diesel, but the documents indicate fuel oil, heavy oil and lubricating oil also leaked into the river.

The amounts varied:

- 1/2 of the spills were for an amount less than 10 litres.

- 1/4 were for between 10,000 and 50,000 litres.

- 1/4 were of an “unknown quantity.”

A ship near Trois-Rivières, for example, leaked an untold amount of diesel into the water in December 2014.

Neither the provincial government nor the federal government could say how much of the 22,000 litres of diesel on the ship went into the water.

Michel Plamondon, a spokesman for the Canadian Coast Guard, said “10,000 litres of pure hydrocarbons were recovered,” but said it’s impossible to know how much additional oil leaked into the water.

The numbers detailed in the documents don't include spills stemming from a source other than a ship, such as the generator leak at the water filtration plant in Longueuil.