From: on behalf of Panel Registry Subject: FW: TNG registration of ...

Memorandum
To: Federal Review Panel for the Prosperity Gold-Copper Project
<strong>From</strong>: Ann Maest, PhD; Cameron Wobus, PhD; Constance Travers, MS; James Holmes,
MS; Jeff Morris, PhD, Stratus Consulting Inc.
cc: Chief Bernie Elkins, Tsilhqot’in National Government; Chief Anne Louie,
Williams Lake Indian Band
Date: 4/16/2010
Subject: Information and arguments to be presented at Prosperity technical sessions
The Tsilhqot’in National Government and the Williams Lake Indian Band retained our company,
Stratus Consulting Inc. of Boulder, Colorado, to review the Prosperity Gold-Copper Mine
Project environmental impact statement (EIS). On November 9, 2009, we provided our initial
comments on the hydrometeorology model that Taseko Mines Ltd. and their contractors, Knight
Piésold (together, the Proponents), used to make predictions about future water quantity and
quality issues at the mine (see Document #1345). The Proponents have provided some responses
to our initial observations. In the technical sessions during the week of April 26, 2010, we will
reiterate and expand our critique of the Prosperity plan.
Stratus Consulting has investigated contaminant releases from hundreds of hard-rock mine sites
worldwide, including in Canada, the United States, Europe, Central America, Africa, South
America, and Asia. In the combined experience of the authors of this memorandum, we have not
seen an open pit copper mine with a waste rock and tailings storage facility (TSF) in a temperate
climate that has not adversely impacted downstream and downgradient water quality. We will
provide the panel with specific case studies from our collective experience that demonstrate that
mine proponents routinely underestimate the environmental impacts of proposed mines, and that
downgradient and downstream contaminant releases are not uncommon.
As we outline in the following sections, we will discuss with the panel in greater detail some of
the errors and uncertainties in the proponents’ EIS that make its predictions unreliable. After
reviewing the EIS and subsequent responses to comments from the Proponents, we conclude that
it is likely that the mine as proposed will release mine-related contaminants, including acidity,
metals, metalloids, sulfate, and nitrogen compounds, into groundwater and surface water. These
contaminants are likely to adversely impact salmonid (trout and salmon) fisheries at least in Fish
Creek and the Taseko River.
Dr. Ann Maest will attend the water quality and quantity sessions on Monday and Tuesday,
April 26�27. Dr. Maest is an environmental geochemist who specializes in mine site
geochemistry. She coauthored a comprehensive examination of predicted versus actual water
quality impacts at large mine sites in the United States. Other authors of this memorandum will
assist Dr. Maest via teleconference.
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