Back to the future.

1849 U.S. Department of the Interior is established; conserves and develops the nation's natural resources.

1872 First National Park is established in Yellowstone, Wyoming.

1892 Naturalist John Muir founds the Sierra Club, a nature conservation organization.

1905 National Audubon Society founded; dedicated to long-term protection of wildlife, water, and other natural resources.

1908 Water treatment plants turn to chlorination to kill bacteria, producing water 10 times purer than when filtered.

1916 National Park Service is established to preserve natural landscapes and historic sites.

1930 Chlorofluorocarbons (CFCs) are hailed as safe refrigerants because they are nontoxic and nonflammable.

1935 Soil Conservation Service is established. Helps farmers and ranchers prevent soil erosion.

1936 National Wildlife Federation is founded to educate public about conservation of wildlife and habitats in U.S.

1940 U.S. Fish and Wildlife Service is established. Operates wildlife refuges; runs field stations, fish hatcheries, and research labs.

1946 Bureau of Land Management formed; responsible for planning best uses of land and managing it in the public interest.

1962 Rachel Carson, a marine biologist and writer, publishes Silent Spring, an investigation of the wasteful and destructive uses of pesticides.

1963 First Clean Air Act grants $95 million to local, state, and national air-pollution-control effort.

1964 Wilderness Act creates National Wilderness Preservation System--aimed at conserving 9.1 million acres of uncultivated, unsettled land.

1968 Biologist Paul Ehrlich publishes The Population Bomb, in which he claims the world's population is growing faster than its food supply.

* Photographs taken by Apollo astronauts give Earthlings a new view of their planet.

1970 U.S. Environmental Protection Agency (EPA) is formed to research, monitor, and enforce environmental laws.

* The first Earth Day is celebrated on April 22.

1970 Clean Air Act toughens antipollution laws, but fails to address acid rain and airborn toxic chemicals, such as nitrous oxides (used in the manufacture of aerosols).

1972 Clean Water Act is passed, with the goals of restoring polluted waters and preventing further pollution.

* Oregon becomes the first state to pass a bottle-recycling law.

1973 U.S. passes Endangered Species Act; protects endangered wildlife against hunting, collecting, and other activities that might harm wildlife and their habitats.

* Arab oil embargo creates energy crisis in U.S.

1974 Safe Drinking Water Act requires EPA to set policies to protect nation's drinking water.

1976 National Academy of Sciences reports that CFCs from spray cans are damaging Earth's ozone layer.

1979 Three Mile Island nuclear power plant in Pennsylvania experiences near-meltdown. No reported injuries. U.S. sets higher standards for nuclear safety.

1980 Congress passes Superfund law, requiring EPA to oversee toxic waste cleanups.

1986 Chernobyl nuclear power plant explodes, contaminating large areas of Soviet Union and northern Europe. Soviets report 31 deaths, 200 injuries, 135,000 evacuees; scientists say casualties are higher.

1988 Ocean Dumping Ban declares dumping plastics at sea illegal.

1989 Tanker Exxon Valdez runs aground, spilling 11 million gallons of oil into Alaska's Prince William Sound.

1990 Congress amends Clean Air Act of 1970; sets stricter standards for air quality; calls for cuts in power plant emissions to reduce acid rain.

1991 Persian Gulf war emphasizes U.S. dependence on imported oil; oil fires underscore the environmental damages of war.

1992 U.S. and more than 100 other nations agree to end production of ozone-depleting CFCs by 1996.

* NASA reports the ozone "hole" over Antarctica is more than 2.5 times the area of the U.S.--the largest on record.

* U.N. reports that destruction of tropical rain forest is 50 percent worse than a decade ago. Rate of destruction: 162,000 k[m.sup.2] per year.

1993 Record flooding of the Mississippi River fuels concern about flood-control projects and loss of wetlands habitat.

1994 Florida embarks on large-scale plan to restore Everglades wetlands. Marjory Stoneman Douglas began the battle 74 years ago.

* Thirty gray wolves--once hunted to near-extinction in the U.S.--are brought back to their natural habitat in Idaho and Yellowstone National Park.

* Some 180 nations meet at the United Nations International Conference on Population and Development in Cairo, Egypt, to discuss environmental impacts of the world's growing population.

2000...