Visible by: Everyone
Attribution + no derivative
Colorado River Aqueduct at Mt San Jacinto (0416)
This may be the access port for the aqueduct itself. It's the same size and shape as the ones we see out in the desert, but those are metal with open vents. You can hear and smell the water rushing below ground. The metal ones are always identified with MWD identification and numbers. This concrete, however, bears no markings and has no vents at all. It's tightly sealed.