There are international, federal and state laws that are designed to conserve natural resources. 

Here are some of the more important ones:

Name	Year	What it does
National Environmental Policy Act (NEPA)	1969	Requires all federal agencies to prepare an Environmental Assessment (EA), and if their work will affect the environment, an Environmental Impact Statement (EIS). An EIS describes the impact of a proposed project and also the alternatives to the project.
Endangered Species Act (ESA)	1973	Protects endangered and threatened species because these species "are of esthetic, ecological, educational, historical, recreational, and scientific value to the Nation and its people," according to the ESA. The act requires that federal agencies ensure that their work does not jeopardize the continued existence of those species or their habitat.
Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)	1963	An international agreement to limit people collecting and buying endangered and threatened species. It started in 1963 but became official policy in 1973 when 80 countries voluntarily agreed to it.
Clean Air Act (CAA)	1970/1990	The Clean Air Act was created in the US in 1970, with major amendments added in 1990. The Clean Air Act authorizes the Environmental Protection Agency (the EPA) to set limits on certain air pollutants. These air pollutants include the chemicals that destroy atmospheric ozone, pollutants that are toxic, and pollutants that cause smog, haze and acid rain. Since air pollution is…well, in the air, it can have effects over large areas. The Clean Air Act protects people and wildlife throughout the entire US.
Clean Water Act (CWA)	1948/1972	The Clean Water Act regulates water pollution and protects wetlands in the US. The EPA sets pollution limits for the Clean Water Act, just as it does for air pollutants covered under the Clean Air Act. The Clean Water Act began its life as the Federal Water Pollution Control Act in 1948, but was significantly changed in 1972 to its current state.

Brain Snack

As part of the ESA, the US Fish and Wildlife Service keeps a list of endangered and threatened species. See the list of endangered species here.