alternative energy
american culture
arizona
black canyon
blue
boulder canyon
built structure
clear sky
color image
colorado river
concrete
dam
day
energy
famous
famous place
fuel and power generation
high angle view
hoover dam
horizontal
hydroelectric power
hydroelectric power station
international landmark
lake
lake mead
landmark
landscape
nevada
outdoors
panoramic
power station
renewable energy
reservoir
river
sky
southwest usa
usa
water
wide angle