CARO News

MDMER Amendments: What your Environmental Team Needs to Know Before June 2021

Posted on April 28, 2021

Starting June 1, 2021, metal and diamond mines in Canada must be compliant with the latest revisions to the Metal and Diamond Mining Effluent Regulations (MDMER), published in 2018. According to Environment Canada, these changes aim to improve the efficiency of Environmental Effects Monitoring (EEM) studies, without compromising environmental protection. To help you navigate these changes, we reached out to the Mining and Processing Division of Environment Canada to understand what you can expect in the upcoming months. If you are interested in their responses and how these changes might impact your business, dig in!

Developed to reduce threats to fish and their habitats, the Metal and Diamond Mining Effluent Regulations (MDMER) provide strict guidelines to mine operators and imposes quality standards on mining effluents. Until 2018, the MDMER was known as the Metal Mining Effluent Regulations (MMER) and applied only to metal mines across Canada. In 2018, the diamond mining sector was incorporated into the scope of the MMER, leading to the current day MDMER which provides regulatory clarity across all sectors.

Starting in June of this year, the mining sector in Canada will be required to adhere to more stringent effluent quality standards, including new rules for acute toxicity, aiming to reduce risks to fish and their habitats. If you are an existing mine operating under the MDMER, you will see more stringent effluent quality standards for arsenic, cyanide, and lead (referred to as “deleterious substances” in the Regulations), as well as additional limits for un-ionized ammonia. The amendments do not change the effluent quality standards for copper, nickel, zinc, total suspended solids, or Radium-226 for existing mines.

Alternatively, if you are a new mine that is being permitted under the MDMER on or after June 1, 2021, or if you are a closed mine that is reopening on or after this date, you will see lower limits for copper, lead, nickel, and zinc in addition to the amended standards described above for existing mines.

Further to the changes in regulatory limits for deleterious substances, guidelines have been established for the simultaneous monitoring of impacts on rainbow trout and Daphnia magna, through acute lethality testing. Daphnia magna is a freshwater invertebrate whose biological response to effluent can be used to assess effluent lethality to species that are main food sources for fish. This requirement is intended to add clarity to the impacts of effluent on overall fish habitats, in addition to the fish themselves.

No conversation around the amendments to the MDMER is complete without a discussion around un-ionized ammonia, the bioproduct of blasting and gold extraction from ore using cyanide. Previously unregulated under the MDMER, unionized ammonia has now been introduced with a regulatory limit of 0.05 mg/L. This limit may come as no surprise to mines in some Canadian provinces where ammonia is regulated provincially, while others may be faced with the challenge of implementing new effluent treatment options to become compliant.

According to the Mining and Processing Division (2021), it is expected that at least 25 metal mines across Canada will be required to make changes to their treatment methods to comply with the new regulations. For the remaining mines, “historical data indicated that they should be able to meet the provisions for all of the prescribed deleterious substances and Daphnia magna without making changes to their current treatment operations.” (Mining and Processing Division, 2021)

In a 2018 study published in the Canada Gazette, the net incremental cost on industry related to these amendments was estimated to be $33.9 million between 2018 to 2027. The ratio of these estimates relative to the industry’s estimated revenue in 2016 was 0.9% for the metal mining sector and 1.7% for the diamond mining sector. In exchange for this financial investment, it is anticipated that these revised regulations will have positive impacts for fish and their habitats across Canada. If you would like further information on this study, please refer to the Regulatory Impact Analysis Statement which includes a cost-benefit analysis of the Amendments, here: Canada Gazette, Part 2, Volume 152, Number 11: Regulations Amending the Metal Mining Effluent Regulations: SOR/2018-99.

If you are working in the mining sector, or supporting a client who is, we are here to help! Our charismatic scientists perform toxicity, metals and inorganics testing on mine effluent, and have systems in place to help you monitor compliance and act quickly in the event of exceedance. If you would like to learn more about our services, shoot us a message at any time: [email protected].

PS – If you were looking for specific information about the Metal and Diamond Mining Effluent Regulations (MDMER) and didn’t find it in this article, you can see a full list of the amendments here.