- subthalamic
- subambient temperature
- sulfuric anhydride
- supplementary purification
- surface area
- surface detection
- surface layer
- sulphate
- sulphur budget
- suspended particle
- swallet
- swath
- tar ball
- tectogenesis
- tectonic trend
- synergy
- temperate zone
- temporal variation
- temporal fluctuation
- tension member
- tidal friction
- thunderstorm rainfall
- time trend
- toxic substance
- total deposition
- towing gear
- toxic effect
- transfer pump
- transformation rate
- transition lake
- transport model
- tug boat
- under flooding
- unspoilt land
- used oil
- usual flood
- vegetable blanket
- vehicular pollution
- vertical dispersion
- vortex skimmer
- waste management
- waste site
- wastewater discharge
- water pollutant
- warning flood
- washout rate
- waste recovery
- wastewater control
- water pollution
- water protection
- water reclamation
- waterless
- weathered oil
- weekly rainfall
- weir skimmer
- wet deposition
- wet year
- wet precipitation
- wet environment
- wet period
- wet scrubbing
- white product
- winter runoff
- woodsy
- wring
- wringer
- yearly discharge