Osisko Development : Environmental Policy

OSISKO DEVELOPMENT CORP.

ENVIRONMENTAL POLICY

OBJECTIVE AND SCOPE

As a responsible mining company, Osisko Development Corp. (the "Corporation") understands the importance of sustainable development and is committed to reducing the potential impact of our operations on the environment. Our goal is to design and operate our sites with the least amount of environmental impacts possible, and we aspire to maintain and, when possible, improve the environmental conditions surrounding our mining projects, from the exploration phase to closure of our operational sites.

APPLICABILITY

This environmental policy (the "Policy") applies to all Osisko Development employees as well as third party workers and business partners that participate in development activities for the company either directly or indirectly. It is applicable to all sites and in all phases of the mine life cycle including exploration, design, construction, operation and closure.

OUR COMMITMENT

This Policy outlines our commitments to protecting the environment and preserving natural resources. These commitments are described below:

• • We will comply with all relevant laws and regulations related to environmental protection, for instance those related to air and water quality, waste disposal, and land reclamation.

• • We will plan, design, construct and operate tailings facilities in compliance with regulatory requirements, company standards, sound engineering principles and applicable industry best practices. Tailings facilities will be subject to a periodic independent review of tailings management with the objective of reducing risks and promoting health, safety, and environmental performance.

• • We will implement and maintain an effective internal environmental management system to identify, assess, and manage the environmental risks and impacts associated with our operations. This includes regular monitoring and reporting of environmental performance, over and above that required under our respective permits.

• • We will work consciously to minimize the use of natural resources, including water, energy, and raw materials, and will promote the efficient use of these resources in our operations.

• • We will take proactive measures to prevent pollution by implementing best practices for waste management, emissions reduction and spill prevention.

• • We will promote the use of commercially proven clean sources of energy and best available technologies to minimize the environmental impact of our operations.

• • We will protect biodiversity, including wildlife habitats and ecosystems, within and around our mining operations. We will develop and implement management plans to prevent biodiversity loss.

• • We will actively engage with our stakeholders, including local communities, Indigenous nations, regulators, and other interested parties, in a transparent, constructive and collaborative manner, to understand their concerns and seek their input on environmental matters.

• • We will plan for the progressive rehabilitation and closure of our mining operations in accordance with regulatory requirements and best practices. This includes developing reclamation plans to ensure physical and chemical long term rehabilitation and providing safe closure of mine sites.

• • We will establish and maintain emergency response plans to effectively respond to and mitigate any environmental incidents or accidents that may occur during our operations.

• • We are committed to continuous improvement in our environmental performance and will regularly review and update our environmental policies, practices, and technologies to ensure that they align with the latest industry standards and best practices.

POLICY REVIEW

The Policy regarding environment will be reviewed annually by the Environment and Sustainability Committee.

By adhering to these commitments and integrating environmental considerations into our operations, we aim to minimize our environmental impact, protect the natural environment, and contribute to a sustainable future for our communities and the planet.

__________________________________________

Sean Roosen

CEO Osisko Development Corp.

Issued: May 26, 2023

Version: 2.0

Review Date: November 8, 2023

Responsible Committee: Environment and Sustainability Committee

This Policy has been approved by the Board of Directors of Osisko Development. Osisko Développement Corp. / Osisko Development Corp.

1100 Avenue des Canadiens-de-Montréal | Bureau 300 Montréal, QC H3B 2S2