Updating the Metal and Diamond Mining Effluent Regulations

Apr. 8 2019

In the Spring of 2017, Environment and Climate Change Canada (ECCC) published proposed amendments to the Metal Mining Effluent Regulations (MMER) in the Canada Gazette, Part I (ECCC 2017) [1]. On May 30th 2018, the finalized amendments were published in the Canada Gazette Part II under the expanded title of Metal and Diamond Mining Effluent Regulations (MDMER).

Strengthening Effluent Standards

The MDMER changes are aimed at strengthening the effluent quality standards, improving the efficiency of environmental effects monitoring (EEM) and adding diamond mines to the regulations.

"The objectives of the Amendments are to reduce the risks of the negative effects of mines on fish and fish habitat, improve the efficiency of certain performance measurement and evaluation requirements, and provide regulatory clarity regarding releases of effluent to fish-frequented water bodies for diamond mines."

Canada Gazette Part II, May 30, 2018

Certain changes to effluent quality standards and some components of EEM rely on the ability of commercial analytical laboratories to deliver accurate and appropriate data to meet the needs of monitoring programs.

Additional considerations around data quality and quality assurance are becoming increasingly important as monitoring programs begin to take advantage of lower detection limits at the analytical labs.

Analytical Technologies to Meet Future Effluent Regulations in Mining

To meet the proposed effluent monitoring standards, laboratories are faced with three key analytical challenges:

  • Reaching required reporting (detection) limits
  • Presence of interfering species
  • Complex sample matrices

In order to achieve the analytical sensitivity required to produce reliable and defensible data at the levels of the new standards, contract analytical laboratories are challenged to provide increasingly lower limits of detection without compromising the integrity, validity and representativeness of the analytical results. To do so, suppliers of laboratory testing services must implement newer technologies to minimize data variability at trace (part-per-billion) and at times, ultratrace levels (part-per-trillion) levels as shown in Figure 1.

Figure 1: Achievable Limits of Detection for Metals by Various Analytical Technologies

Achievable Limits of Detection for Metals by Various Analytical Technologies

Analytical Requirements for Metal or Diamond Mining Effluent

The majority of the Amendments involve the support and services of a commercial analytical laboratory, including water chemistry and ecotoxicology capabilities. Effluent samples from mine sites are not always ideal samples from an analysis perspective. Interferences such as salinity, sulphates, pH and TDS can sometimes require dilution of samples, resulting in raised detection limits above the regulatory standards. Much cleaner laboratory protocols and facilities have become the norm in order to satisfy the quality assurance and quality control protocols specific to new instrumentation operating at ultratrace concentrations. This produces better environmental data and ultimately higher confidence in the mine’s analytical laboratory partner. The ability to measure lower concentrations of the substances included in the MDMER provides greater definition of what may be happening in the water treatment system and can result in proactive mitigation of deficiencies ahead of non-compliance with the discharge limits or challenges with toxicity testing.

Strengthening Effluent Quality Standards

Prescribed Deleterious Substances

As of June 1, 2018, the Amendments had imposed more stringent limits for arsenic, copper, cyanide, lead, nickel and total ammonia. As well, diamond mines have been subject to the same effluent discharge limits as metal mines.

Effective June 1, 2021, the new MDMER limits will be in place for metal and diamond mines shown in Table 1. Weekly un-ionized ammonia sampling will be required including pH and temperature at time of sample collection. Should the monthly mean concentration of arsenic, copper, cyanide, lead, nickel, zinc or un-ionized ammonia be less than 10% of the authorized monthly mean concentration for 12 consecutive months, the mine may reduce the reporting frequency to not less than once each calendar quarter.

Effluent Monitoring Conditions - Acute Lethality Testing

Effective June 1, 2021, no less than once per month, when salinity of the effluent is less than ten parts per thousand and effluent is not deposited into marine waters, the MDMER requires that mine effluent not be acutely lethal to Rainbow Trout. In addition, when salinity is less than four parts per thousand and effluent is not deposited into marine waters, the MDMER requires that mine effluent not be acutely lethal to Daphnia Magna for mines to maintain their authority to deposit. Threespine Stickleback is a marine species can now be used to test for acute lethality when salinity is equal or greater than ten parts per thousand and effluent is deposited into marine waters. When effluent is determined not acutely lethal for 12 consecutive months, the testing frequency may be reduced to once in each calendar quarter from that final discharge point.

Table 1: Effluent Limit Comparisons (μg/L)

Arsenic 500 300 100 2.5
Copper 300 300 100 1
Cyanide 1,000 500 500 5
Lead 200 100 80 0.5
Nickel 500 500 250 12.5
Zinc 500 500 400 10
Radium-226 0.37 Bq/L 0.37 Bq/L 0.37 Bq/L 0.01 Bq/L
TSS 15,000 15,000 15,000 2,000
Un-ionized Ammonia No Limit 500 500 50

Transitional Provisions: Diamond mines may use study data collected during a consecutive 12-month period prior to final publication to determine if they may go on reduced frequency for Rainbow Trout and Stickleback acute lethality tests. For Daphnia Magna acute lethality testing, both metals and diamond mines can use study data collected in a consecutive 12-month period prior to June 1, 2021 to determine eligibility for reduced testing frequency.

Environmental Effects Monitoring

New Species, New Methods

As of January 1, 2019, existing metal mines were subject to EEM changes. Biological monitoring studies that commenced on or before June 1, 2018 are to be completed using previous MMER Environmental Effects Monitoring (EEM) provisions.

Effective June 1, 2021, all EEM requirements apply to diamond mines.

Sublethal Toxicity Testing Considerations

As of January 1, 2019, sublethal testing in metal mines is to be performed on fish (fathead minnow or rainbow trout), invertebrate (Ceriodaphnia dubia), plant (Lemna minor), and algal (Pseudokirchneriella subcapitata) species, two times per year for three years.

After three years, mines will be required to conduct a sublethal toxicity test on the most sensitive (site-specific) species once per calendar quarter. For mines previously subject to the MMER, results of tests done under the MMER can be used to determine the most sensitive species.

Diamond mines come under the updated EEM requirements as of June 1, 2021.

Water Quality Monitoring

As of January 1, 2019, chloride, chromium, cobalt, manganese, phosphorus, sulphate, thallium and uranium were added to the water quality analysis suite. Reporting for ammonia has been changed to providing the un-ionized ammonia concentration based on calculations including total ammonia (expressed as N), pH and temperature.

Water quality sampling under Schedule 5 [1] shall be conducted four times per calendar year at least one month apart.

Reporting of 2019 data will be via submission to ECCC using the new Mine Effluent Reporting System (MERS), replacing the outdated Regulatory Information System (RISS).

Biological Monitoring Studies

As of January 1, 2019, additional biological monitoring studies may include:

  • Requirement for a mercury fish tissue study if the annual average concentration in the effluent is equal to or greater than 0.1 μg/L, unless the results of the previous two biological monitoring studies indicate no effect on fish tissue from mercury.
  • Requirement for a selenium fish tissue study if the annual average concentration in the effluent is equal to or greater than 5.0 μg/L (or grab sample equal to or greater than 10 μg/L), unless the results of the previous two biological monitoring studies indicate no effect on fish tissue from selenium.
  • Requirement for a benthic invertebrate community study if the effluent concentration is greater than 1% at 100m from the final discharge point.


[1] Environment and Climate Change Canada. 2017. Regulations Amending the Metal Mining Effluent Regulations. Vol. 151, No. 19 – May 13, 2017.