abstract
broke
cement
city
cleanup
concrete
contamination
danger
dirt
dirty
ditch
drain
dump
ecological
ecological problems
ecology
environment
factory
flood
flowing
forbidden
garbage
gutter
industrial
industry
landmarks
nature
pipe
pollution
problem
real
river
ruins
rust
rusty
sewage
sewer
stream
substance
town
toxic
tunnel
ugliness
unhygienic
unpleasant
urban
waste
water