NASA says that a day on the earth is now longer because of China's massive Three Gorges Dam is subtly altering Earth's rotation. The dam's reservoir holds about 10.6-trillion gallons of water when filled, which would mean this mass redistribution could lengthen the day by 0.06 microseconds and slightly change Earth's shape.
Large-scale constructions like the Three Gorges Dam can have minute effects on Earth's rotation due to mass redistribution, but these impacts are extremely small and well within the range of natural variations. China has now approved 360 billion dollars for construction on an even bigger dam!