Over the course of three years preparing the Bristol Bay Watershed Assessment, the EPA has consulted more than 700 scientific sources, received more than 1 million comments and visited the Bristol Bay a number of times. Its major findings do not differ significantly between its first draft and its final: the agency predicts that significant direct impacts to fish-bearing streams are inevitable if a large-scale mine is developed in the area of the Pebble deposit, and devastating effects to aquatic life and habitat would occur if the mine's tailings facility were to fail.
In the Bristol Bay Watershed Assessment, EPA describes the Bristol Bay watershed and its resources, and then assesses direct and indirect results of large-scale mining at the Pebble deposit. This risk assessment addresses a range of mining scenarios, based on Northern Dynasty Minerals' 2011 Preliminary Assessment, which described for its investors mining scenarios for 20, 25 and 78 years of mining. The largest scenario EPA considers is based on extracting 6.5 billion tons of ore. However, the Pebble deposit contains an estimated 11.9 billion tons of ore. EPA notes that "were a mine to be developed that fully extracted this amount of ore, potential effects could be significantly greater than those estimated in the assessment."
How the document has changed
During the course of its assessment development, additional studies became available to the EPA, including the "Environmental Baseline Document" published by the Pebble Limited Partnership in early 2012. While major findings did not change significantly between drafts, the EPA did respond to public and peer review comments to reorganize information and include detail in some sections. For example, the agency expanded its description of compensatory mitigation options in Appendix J in response to several requests for this information. EPA has published a comment-by-comment response to suggestions made by its independent peer review team and is currently preparing a similar document that will detail its responses to more than 5,000 public comments.
EPA Watershed Assessment Timeline - A Pebble Watch graphic
EPA Watershed Assessment
Pebble Watch Summaries
Final version (coming soon)
About Pebble Watch
Pebble Watch is an impartial, educational and fact-based initiative of the BBNC Land Department to disseminate information regarding the proposed Pebble Mine project to BBNC shareholders and interested parties.