Reuse

Right to Know

Risk

Rivers and Harbors Appropriations Act

Science

Scrubbers

Sedimentation

Settlement House Movement

Smart Growth

Smelting

Smog

Snow, John British Anesthesiologist (1813–1858)

Soil Pollution

Solid Waste

Space Pollution

Sprawl

Strong, Maurice Canadian Environmental Advocate; First Executive Director of the United Nations Environment Programme (1929–)

Sulfur Dioxide

Superfund

Sustainable Development

Swallow, Ellen

Systems Science