In its final assessment of the impact of mining in the Bristol Bay region of southwestern Alaska, the EPA has not retreated on its proposed findings that widespread, severe, and possibly irreparable harm may result from the industrial scenarios that form the basis of its investigation. 

The Agency acknowledges that its assessment is limited by uncertainties since actual plans to extract as much as 11 billion tons of copper, gold, and other ores have not been submitted by the Pebble Partnership, the consortium of engineering firms that is seeking to mine the region.  But those uncertainties generally do not favor industry since the Agency believes it may be underestimating the damage that may result from mining. 

In a quick response, the Pebble Partnership states that the hypothetical mine the EPA used in its study “did not employ the most advanced engineering and mining practices, as will most certainly be used at Pebble.”

Largest salmon fishery

With runs averaging 37.5 million fish per year, rivers in the Bristol Bay watershed support the largest sockeye salmon fishery in the world.  The region also has 25 federally recognized tribal governments.  According to the EPA, virtually every household in the watershed uses subsistence resources, and salmon constitute approximately 52 percent of the subsistence harvest; for some communities this proportion is substantially higher.

The EPA says it developed “realistic mine scenarios” drawn from a variety of mining interests and included baseline data collected by the Pebble Partnership to characterize the mine site, mine activities, and the surrounding environment. 

“The exact details of any future mine plan for the Pebble deposit or for other deposits in the watershed will differ from our mine scenarios,” states the Agency.  “However, our scenarios reflect the general characteristics of mineral deposits in the watershed, modern conventional mining technologies and practices, the scale of mining activity required for economic development of the resource, and the infrastructure needed to support large-scale mining.  Therefore, the mine scenarios evaluated in this assessment realistically represent the type of development plan that would be anticipated for a porphyry copper deposit in the Bristol Bay watershed.”

Streams and wetlands

Depending on the extent of routine mining activities, the EPA believes adverse consequences could include the following:

• Destruction of 24 to 94 miles of salmon-supporting streams and 1,300 to 5,350 acres of wetlands, ponds, and lakes;
• Altered stream flows affecting the ecosystem structure and function of an additional 9 to 33 miles of salmon-supporting streams; and
• Adverse direct and indirect effects on fish in 13 to 51 miles of streams from waste and wastewater management.

Engineering failures

The assessment also looked at the potential for a wide range of engineering and transportation failures involving wastewater treatment plants, culverts, tailings dams, pipelines, and trucks.  For example, in one scenario, the EPA projects that dam heights could exceed 200 meters.  Given that height and the subarctic conditions, the EPA states that it cannot be known if standard practice or state-of-the-practice dams will perform as expected.  According to the assessment, a tailings spill could eliminate 29 percent or more of the Chinook salmon run in the Nushagak River, one of the two rivers in the region accommodating the largest populations of salmon. 

Also, the ore deposit would be mined for decades and wastes would require management for centuries or even in perpetuity, according to the EPA. “Engineered mine waste storage systems have been in existence for only about  50 years, and their long-term behavior is not known,” cautions the Agency. 

The EPA adds that the assessment is intended to “inform future government decisions” and “does not reflect any conclusions or judgments about the need for or scope of potential government action, nor does it offer or analyze options for future decisions.”

Rush to publish?

The Pebble Partnership is concerned that the EPA produced the assessment in a shorter time and with fewer resources than the Agency committed to assessments of areas much smaller than Bristol Bay. 

“[The Pebble Partnership] has spent many years and $600 million on engineering and environmental studies to develop a plan for a 21st century mine,” said John Shively, the Partnership’s CEO.  “We understand the critical role salmon plays in this region of Alaska, both culturally and commercially.  [The EPA’s assessment] is both a poorly conceived and poorly executed study, and it cannot serve as the scientific basis for any decisions concerning Pebble.”

The final Bristol Bay assessment