The short answer to your question is that energy supply in the U.S. is not centrally managed by the government. The U.S. energy grid exists as the sum of volunt

The short answer to your question is that energy supply in the U.S. is not centrally managed by the government. The U.S. energy grid exists as the sum of voluntary private efforts to generate power to make money. The government--actually governments, since there are autonomous local, state, and federal layers in the U.S.--do play an important role in regulating and coordinating the system. But most power generation is not owned or funded by the government, and fundamentally it is not the government's responsibility to fund new generation. If there is a forecasted shortfall in energy, that will be expressed in prices going up, which will attract investment in new generating capacity. So, we don't need every bit of existing generation to stay online. Power plants are idled and decommissioned every year, as more efficient (and therefore less expensive) new power plants come online and soak up the demand. Hydro power plants are not immune from this. Each decision to build new generating capacity, or take old generating capacity offline, is made on its own merits, in the context of what people know at that moment. It might seem frighteningly disorganized at first, but in the long run it is the best way to do things because of the flexibility built into the system.