Final answer:
The EPA, established in 1970, governs the U.S. environmental regulations including the Clean Air Act and Clean Water Act, aimed at reducing pollution and improving environmental quality despite facing challenges like high costs of compliance and state-level implementation.
Step-by-step explanation:
The U.S. government agency responsible for promoting clean air, land, and water is the Environmental Protection Agency (EPA). This agency was created in 1970 to oversee environmental laws, including the implementation of the Clean Air Act and the Clean Water Act. These laws have significantly improved America's environment over recent decades. However, there have been difficulties with command-and-control regulations, such as high compliance costs for U.S. firms, which some economists estimate to be over $200 billion per year. While command-and-control approaches have led to cleaner air and water, they have also led to a dialogue about the efficiency and cost-effectiveness of these types of regulations. With command and control, the EPA sets federal standards for environmental quality, leaving it to states to develop plans to achieve these standards, occasionally resulting in legal challenges like the one cited in the LA Times article about states suing the EPA over mercury emissions. The underlying principle of command and control is to prevent pollution before it occurs, shifting from traditional end-of-pipe solutions towards preventive strategies.