Osisko Tables Environmental Impact Study for Its Canadian Malartic Project

MONTREAL, QUEBEC, Sep 05 (MARKET WIRE) --
Osisko Mining Corporation ("Osisko") (TSX: OSK)(FRANKFURT: EWX) submitted
yesterday its environmental impact assessment study for its Canadian
Malartic mining project to Quebec's Ministere du Developpement durable,
de l'Environnement et des Parcs (MDDEP).

"We're very pleased to reach this major milestone in the regulatory
approval process." said Mr. Sean Roosen, President and CEO of Osisko. "To
conduct this study over the past year we've had to call on many experts
in many fields, and we are extremely proud of the result. From the start
of our project, we have been committed to optimizing the positive impacts
of our project for the town of Malartic, the Abitibi-Timiskaming region
and the Province of Quebec, while striving to minimize impacts on the
physical and human environment. We are working diligently as responsible
corporate citizens to achieve successful integration between the two."

The impact study concludes that given the chosen site for mining
infrastructure, the selected technology, and the open communication with
the various stakeholders, the Canadian Malartic project would have a
minimal impact on the environment and the population and well within
acceptable industrial norms. Moreover, Osisko has demonstrated with its
work to date that it is a major partner in the responsible development of
Malartic and its surrounding area. The impact study also underscores
significant spin-offs the project would have on the local and regional
economy. Highlights of the impact study are appended to this press
release.

Osisko remains committed to providing the population of Malartic with
thorough and transparent information on the evolution of the Canadian
Malartic project. With this goal in mind, the Company will send
information to Malartic residents over the coming weeks summarizing the
study and explaining the main findings.

Copies of the study will be available for consultation at the Osisko
community outreach office, located at 864 rue Royale in Malartic, and at
the Malartic Town Hall. The study is also available online, along with
the supporting documents, on the Osisko website at: www.osisko.com.

Moving Forward

The study will be reviewed by Quebec government authorities to establish
compliance with MDDEP guidelines. During this time and until the study is
declared admissible by the MDDEP, Osisko will answer any questions
received from the government and provide additional information as
requested.

The BAPE public hearing process will start following the MDDEP's review
of the study, leading to a report that will be submitted for approval to
members of the Quebec Cabinet.

Cautionary Note: the Canadian Malartic mineral resource is not a mineral
reserve, and the economic feasibility of the project has not been
demonstrated. The mineral resource estimate for the Canadian Malartic
project includes an inferred resource. This estimate is considered too
speculative from a geological standpoint to apply economic parameters
that would make it possible to consider it a mineral reserve. Moreover,
there is no assurance that subsequent work will result in an economically
mineable mineral reserve.

Forward-looking statements

Certain statements contained in this press release may be deemed
"forward-looking statements". All statements in this release, other than
statements of historical fact, that address events or developments that
the Corporation expects to occur, are forward-looking statements.
Forward-looking statements are statements that are not historical facts
and are generally, but not always, identified by the words "expects",
"plans", "anticipates", "believes", "intends", "estimates", "projects",
"potential", "scheduled" and similar expressions, or that events or
conditions "will", "would", "may", "could" or "should" occur. Although
the Corporation believes the expectations expressed in such
forward-looking statements are based on reasonable assumptions,
including, without limitation that all technical, economical and
financial conditions will be met in order to put the Canadian Malartic
Project into commercial production, such statements are not guarantees of
future performance and actual results may differ materially from those in
forward-looking statements. Factors that could cause the actual results
to differ materially from those in forward-looking statements include
gold prices, access to skilled consultants, mining development and mill
production personnel, results of exploration and development activities,
the Corporation's limited experience with production and development
stage mining operations, uninsured risks, regulatory changes, defects in
title, availability of personnel, materials and equipment, timeliness of
government approvals, actual performance of facilities, equipment and
processes relative to specifications and expectations, unanticipated
environmental impacts on operations, market prices, continued
availability of capital and financing and general economic, market or
business conditions. These factors are discussed in greater detail in the
Corporation's most recent Annual Information Form filed on SEDAR, which
also provides additional general assumptions in connection with these
statements. The Corporation cautions that the foregoing list of important
factors is not exhaustive. Investors and others who base themselves on
the Corporation's forward-looking statements should carefully consider
the above factors as well as the uncertainties they represent and the
risk they entail. The Corporation believes that the expectations
reflected in those forward-looking statements are reasonable, but no
assurance can be given that these expectations will prove to be correct
and such forward-looking statements included in this press release should
not be unduly relied upon. These statements speak only as of the date of
this press release.

APPENDIX: HIGHLIGHTS OF THE IMPACT STUDY

Human Aspect

Particular attention was given to the human aspect of the project's
impacts. Sector studies focused on:

- Health

- Economy

- Quality of life (noise, vibrations, visual aspect, traffic)

- Project acceptability

When consulted by Osisko, the local population voiced its concerns about
noise, vibrations, air quality and visual impacts. The study outlines the
precautions and measures integrated into the project by Osisko to
minimize any impacts on the quality of life for the citizens of Malartic
and the non-organized territory of Lac-Fouillac. The sector study on
health concludes that the project poses no threat to surrounding
populations, notably in terms of airborne metal emissions.

From an economic standpoint, a little more than a third of Osisko's mine
construction and development expenditures, totalling 540 million dollars,
would be made in the Malartic and the Abitibi-Timiskaming region. Osisko
will implement a policy to maximize the local and regional acquisition of
goods and services, as well as the hiring of its workforce from the
Malartic and the Abitibi- Timiskaming region. While in production, Osisko
expects that 349 of the 392 direct jobs to be created at the potential
mine would be occupied by residents of Malartic and the surrounding
areas. Osisko has also recently created and financed the "Fonds Essor
Malartic Osisko" (FEMO), a sustainability fund designed to ensure
long-term benefits for Malartic created by Osisko's presence in the
region.

Finally, the study highlights the structuring effect that the Canadian
Malartic project would have on the development of municipal lands and on
the start-up of environmental projects at the regional level. Thus, it
would give the municipality of Malartic a stronger voice on matters of
sustainable development within the Vallee-de-l'Or Regional County
Municipality (MRC).

Physical Environment

Impacts on the physical environment were the focus of several sector
studies dealing with:

- Air

- Water

- Soil

- Vegetation & Wildlife

Overall, most of the expected impacts of the Canadian Malartic gold
mining project have been deemed minor, mainly due to the following
factors:

- There will be some overlap between the proposed mining facilities and
existing installations from the former Canadian Malartic and East
Malartic mines, which were closed in 1965 and 1983 respectively;

- Osisko intends to locate the new facilities within the confines of
watersheds already impacted by previous operations;

- The environment of the proposed new mine has already been disturbed by
decades of mining operations between 1935 and 1983, and as such, the new
project does not involve major impacts from a biological standpoint:
terrestrial and aquatic wildlife populations are not widespread or
diverse;

- None of the areas to be affected are of important impact for Quebec's
wildlife or vegetation, and although some areas will be deforested, this
clearing will be compensated for at the end of the project by the
reclamation and reforestation of the tailings pond and waste pad areas.

Monitoring

In the event the Canadian Malartic project is brought into commercial
production, Osisko is committed to implementing all the mitigation
measures laid out in the impact study, without exception, in addition to
all proposed follow-up and monitoring programs. Osisko intends to
implement a strict monitoring program of groundwater levels from the
start-up of mining operations and would extend the program until the end
of the mine closure process. Osisko would also prepare a groundwater
contingency plan that could be implemented to prevent or minimize any
potential impacts on the natural environment, or any perceived impact on
local water supply. In keeping with this precautionary spirit, Osisko
would follow the same approach for dust, noise and vibrations.

Contacts:
Osisko Mining Corporation
Jean-Sebastien David
Vice-President, Sustainable Development
514-735-7131
david@osisko.com
www.osisko.com

Osisko Mining Corporation
Sylvie Prud'homme
Investor Relations
514-735-7131
Toll Free: 1-888-735-7131
prudhomme@osisko.com

Copyright 2008, Market Wire, All rights reserved.

-0-