The Department of Environment and Conservation (Western Australia) was established on 1 July 2006, bringing together the Department of Environment and the Department of Conservation and Land Management.
DEC is in the portfolio of the Minister for the Environment and Climate Change. The department is also part of the greater environmental community and has distinct Government responsibilities for implementing Government policy within that community. Protection and conservation of the environment is a collective role.

The department has the lead responsibility for protecting and conserving the State's environment on behalf of the people of Western Australia. This includes managing the State's national parks, marine parks, conservation parks, State forests and timber reserves, nature reserves, marine nature reserves and marine management areas.
Its key responsibilities include broad roles in conserving biodiversity, and protecting, managing, regulating and assessing many aspects of the use of the State's natural resources. The department contributes to the development of environmental protection policies, managing the environmental impact assessment process and carrying out regulatory functions to achieve improved environmental outcomes. It is also responsible for management of contaminated sites and coordination of pollution incident responses.

The department is also responsible for fire preparedness and pest animal and weed control on 89 million hectares of unallocated Crown land and unmanaged reserves. The department provides support or assists the following Environment portfolio authorities and boards to carry out their functions which are integral to the department achieving its vision and mission:

• Environmental Protection Authority;
• Conservation Commission of WA;
• Keep Australia Beautiful Council;
• Marine Parks and Reserves Authority;
• Swan River Trust;
• Waste Management Board; and
• Contaminated Sites Committee.

The department contributes to national and international programs through national Ministerial Councils, the Natural Heritage Trust and other national programs, the work of organizations such as the ICUN (the World Conservation Union), and to the implementation of international environmental and conservation treaties in WA.
It employs people with world-class scientific, regulatory, policy, land and marine management, visitor services and educational skills.

The department's eight key objectives are:
1. Conserving biodiversity - Protect, conserve and, where necessary and possible, restore Western Australia's biodiversity.
2. Managing natural resources and promoting environmentally sustainable practices - Protect, manage and, where necessary and possible, restore Western Australia's natural resources, including land, water and air, and promote the adoption of environmentally sustainable practices in the community, industry and government.
3. Leading climate change actions - Provide leadership in the development and implementation of strategies to reduce greenhouse gas emissions, and adaptation initiatives to reduce the impact of climate change for Western Australia.
4. Creating a "World Class Parks System" - Generate environmental, social, cultural and economic benefits through the further development of a "World Class Parks System" in terms of ecosystem management and visitor facilities and services.
5. Implementing sustainable forest management - Generate social, economic and cultural benefits from forest while sustaining their biodiversity, health, vitality and productive capacity.
6. Preventing pollution and remediating contamination - Protect the environment, and people's health and amenity, by ensuring discharges meet approved criteria and contaminated sites are appropriately remediated.
7. Maintaining community involvement and support - develop community awareness and appreciation of the State's natural environment and biodiversity and promote community involvement in and support for its protection and conservation.
8. Improving the way we do business - Foster a positive work culture of trust, continuous improvement and anticipation of environment and conservation issues and customer needs, and deliver core business activities in the most effective and efficient manner.