One Quick Question: The Pebble Mine, salmon, and the future of Bristol Bay

Western Today recently chatted with WWU Associate Professor of Environmental Sciences Jim Helfield for the first installment in a new series called One Quick Question, a space to pose a single question about an item of regional or national importance to a Western faculty member that they are uniquely poised to answer because of their area of scholarship or research expertise.  

A male Alaskan sockeye makes its way upstream

Today, we talked with Helfield about the recent decision by the government to effectively nix the proposed copper and gold Pebble Mine complex in Southwest Alaska because of its potential impact on Bristol Bay, home to the world's largest salmon fishery.  

Helfield has researched salmon populations from Scandinavia to Whatcom County, and his most recent project involves working with students, local tribes, and state fisheries biologists to study summer chinook salmon populations on the Nooksack River's South Fork, and how these salmon are assisted in their survival by the deep pools created by Large Woody Debris (LWD). 

The Pebble Mine decision was one that had been pending for more than 20 years, and was bitterly fought in the courts before the final decision was made. 

WT: Jim, the Pebble Mine proposal was one that pitted environmentalists and commercial and recreational fishers against the mining industry, and it would have resulted in an estimated 10 billion tons of toxic mining waste in an area of crucial environmental and commercial concern. How important was this decision? 

The Nushagak is just one of the crucial salmon rivers that feed into Bristol Bay

JH: "I think the main factor that went into play was the near universal agreement among fisheries scientists that the proposed mine would have adverse and potentially disastrous consequences for water quality and habitat affecting Bristol Bay’s sockeye salmon population.  This decision is crucially important for the long-term viability of salmon stocks in the area, and also the fisheries that depend on them. 

Mine waste can be deadly to fish populations for a number of reasons. After being removed, waste rock is usually stored above ground in free-standing piles.  When rocks containing sulphide minerals are excavated, they react with water and oxygen to form sulphuric acid.  The resulting leachate is known as acid mine drainage (AMD).  AMD will continue to be produced in source rock exposed to air and water until all of the sulphides are leached out, a process that can last hundreds or thousands of years. 

During this process, there is a constant risk of water pollution, as AMD is transported from mine sites in surface drainage to receiving streams, lakes and groundwater.  Further effects stem from extraction of the ore itself and from disposal of tailings (i.e., residues from ore concentration).  Up to 90% of metal ore ends up as tailings, which are commonly dumped in large piles or ponds near the mine. Tailings usually contain residues of toxic organic chemicals used in ore concentrators (such as toluene). 

The finely ground tailings material makes metals that were formerly bound up in solid rock -- like arsenic, cadmium, copper, lead and zinc -- accessible to water, increasing potential for heavy metal contamination in rivers and streams.  These effects are exacerbated by AMD -- but the bottom line is that heavy metals and sulphuric acid are deadly to fish populations."

Jim Helfield has taught at Western since 2005. His research focuses on processes affecting the habitat and ecology of Pacific salmon and trout, and the ways in which these processes respond to and recover from anthropogenic stress. Find out more about the work and research of Helfield and his colleagues in the College of the Environment here