architecture
blue
building activity
built structure
cloud sky
colors
concrete
curve
dam
dyke
electricity
elevated walkway
environment
environmental cleanup
environmental conservation
falling water flowing water
famous place
flowing water
fuel and power generation
high angle view
horizontal
hydroelectric power
hydroelectric power station
idyllic
journey
lake
landscape
montana western usa
national landmark
nature
no people
outdoors
photographic slide
reservoir
running water
sedan
segovia
sky
social issues
spain
summer
sun
sunlight
surrounding wall
swamp
vitality
wall building feature
water conservation
watercourse