background
canal
chemical
contamination
corrosion
danger
deterioration
dirt
dirty
ecology
energy
environment
environmental
factory
fatal
flowing
garbage
global
harm
hazardous
industrial
industry
influence
lake
natural
nature
pipe
pipeline
pollute
pollution
pond
problem
protection
refinery
river
rusty
sewage
sewer
stream
substance
technology
toxic
tube
unhygienic
urban
vector
warming
waste
water