Managing Metal Mining Effluent Quality in Canada

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Overall, in 2014, the metal mining sector achieved over 99% compliance with the authorized limits for metals, cyanide and pH, and over 97% for total suspended solids as set out in the Metal Mining Effluent Regulations (the Regulations). These results have been mostly stable since 2003, except for total suspended solids, for which compliance has increased. The percentage of test results that were not acutely lethal has remained above 95% since 2005.

The Regulations authorize the deposit of specific deleterious substances from metal mines, subject to certain conditions. They also impose limits on the pH level of the effluent, and prohibit the release of effluent that is acutely lethal.Footnote [1]

Percentage of regulatory data submitted by metal mines that did not exceed authorized limits, Canada, 2003 to 2014

Line Chart - See long description below

Long description

The line chart shows the percentage of regulatory data that did not exceed authorized limits for deleterious substances (arsenic; copper; cyanide; lead; nickel; radium 226; zinc; and total suspended solids), pH levels (pH low; pH high) and acute lethality, from 2003 to 2014.

Data for this chart
Percentage of regulatory data submitted by metal mines that did not exceed authorized limits, Canada, 2003 to 2014
Type of test2003
Arsenic (As)99.899.799.599.899.899.8100.099.999.899.899.899.9
Copper (Cu)99.899.699.7100.099.999.799.599.999.999.899.799.7
Cyanide (CN)100.0100.0100.0100.0100.099.2100.0100.099.798.699.399.8
Lead (Pb)99.9100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Nickel (Ni)99.699.298.698.398.599.299.599.299.699.699.899.3
Radium 226 (Ra-226)99.0100.099.8100.0100.099.1100.099.799.999.999.299.5
Zinc (Zn)99.899.999.199.899.899.799.799.799.799.799.899.6
pH low99.799.799.299.699.699.299.599.899.799.999.899.3
pH high99.599.499.699.799.799.399.799.899.899.999.999.8
Rainbow trout acute lethality (toxicity)95.091.797.897.797.095.596.297.397.598.896.899.0
Total suspended solids (TSS)92.195.391.895.493.793.894.595.696.196.397.997.6

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How this indicator was calculated 

Note: Deleterious substances listed in the Regulations include arsenic (As), copper (Cu), cyanide (CN), lead (Pb), nickel (Ni), zinc (Zn), total suspended solids (TSS), and radium 226 (Ra-226). The Regulations set a minimum (pH low) and maximum (pH high) level for the pH of effluent released. Acute lethality test refers to tests of effluent on rainbow trout in terms of mortality.
Source: Environment and Climate Change Canada (2016) Summary Review of Performance of Metal Mines Subject to the Metal Mining Effluent Regulations.

The Regulations apply to all Canadian metal mines (except placer mines)Footnote [2] that exceeded an effluent flow rate of 50 cubic metres per day at any time after June 6, 2002, and that deposit a deleterious substance in any water or place defined in the regulations. Mining operations that are not captured under the Regulations (such as coal mines, diamond mines, quarries, and other non-metallic mineral mining facilities) are still subject to the requirements of the Fisheries Act, including the general prohibition on the deposit of deleterious substances.

Metal mining is an important economic activity for the Canadian economy. In 2014, the metal ore mining industry employed 35 855 Canadians,Footnote [3] and contributed 1.1% of Canada's gross domestic product.Footnote [4] Canada ranks among the top five countries in the mining of a number of major metals.Footnote [5],Footnote [6] However, without adequate regulation, metal mining could have harmful impacts on the environment. For example, the effects of untreated mining effluent could be highly damaging to the receiving aquatic environment, including fish and fish habitat. Proper management regimes can mitigate these impacts.

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