New work published in Achievements of science synthesizes the impacts of metal and coal mining on salmon and trout in northwestern North America and highlights the need for more complete and transparent science to inform mining policy.
This is the first comprehensive effort by an interdisciplinary panel of experts to clearly link mining policy to our current understanding of watershed ecology and salmonid biology.
“Our paper does not argue for or against mining, but it describes current environmental issues and gaps in the application of science to mining management. We believe it will provide critically needed scientific clarity on this controversial topic,” said lead author Chris Sergeant, a graduate student in the University of Alaska Fairbanks’ College of Fisheries and Ocean Sciences and a research associate at the University of Montana.
For the study, experts combined and analyzed information on hydrology, river ecology, aquatic toxicology, biology and mining policy. Their robust rating reflects over 3,600 mines throughout Montana, Washington, British Columbia, Yukon and Alaska. Mines range in size from family-run placers to massive open pits.
The study shows that despite an impact assessment designed to assess risk and inform mitigation, the mines continue to harm salmon-bearing catchments by polluting, burying streambeds and altering currents. Sludge suffocates eggs, and embryos may not survive in contaminated groundwater. Heavy metals impair salmon’s sense of smell, affecting their ability to respond to predators and find their way out of the ocean to spawn.
“Not all mines present the same level of risk, but our review has shown that the damage from mining can be severe and long-term. The extent of mining stress on these watersheds underscores the importance of accurately assessing the risk to water, fish and communities,” said Sgt.
The paper also describes how some mining policies fail to take into account the breadth and duration of mining’s environmental impacts or the exacerbated effects of climate change.
“The crux of the problem is that salmon use a large part of the watershed during their life cycle. They move across watersheds, while impact assessments of mining projects tend to be very local and do not adequately consider all the components and impacts of mining,” said CFOS biologist and educator Megan McPhee.
She explained that some impact assessments do not fully assess the infrastructure needed to operate the mine, such as roads, power generation and water removal.
“The other thing is that most mines, once closed, have to be restricted forever. This is a problem because most corporations are not set up that way. Additionally, most mitigation strategies do not account for environmental changes, including melting permafrost and flooding caused by climate change,” McPhee said.
Looking ahead, the authors identify four key challenges that will be fundamental to modern, evidence-based risk assessment and mitigation, starting with understanding the complexity and uncertainty of stressors. Stressors include impacts such as changing hydrology and temperature, habitat change and loss, and pollutants.
Other key challenges are considering the cumulative impacts of mining activities throughout the life cycle of a mine, developing realistic mitigation strategies, and recognizing the potential for increased climate change risk.