The U.S. Environmental Protection Agency's mission is to protect human health and safeguard the natural environment.
Park Net, the National Park Service's home page. Has maps, photos, and information on fees and access.
Nature Net gives information on air and water quality in our national parks.  Also gives a tour.
Bureau of Land Management manages over 270 million acres of land in the United States.
Bureau of Reclamation oversees the construction of major dams.
National Oceanic and Atmospheric Administration
U.S. Fish and Wildlife Service
U.S. Geological Survey conducts scientific studies and surveys of natural resources.