> But any and all energy that Idaho does extract from the river is energy that would otherwise have been available downstream. This is false. Huge portions of

> But any and all energy that Idaho does extract from the river is energy that would otherwise have been available downstream. This is false. Huge portions of that kinetic energy are going to be lost to transfer, heat, and sound if it is not captured by Idaho. > Which hypothetical river contains more energy when it reaches Oregon? Assume a spherical cow... In order for any of your claims to be true, your 'rivers' would have to be straight, frictionless channels. To know the actual impact on flow you would have to measure it. It is possible the flow will be reduced. But this is irrelevant for energy generation, since it is the gravitational potential that is being harvested[0]. Any kinetic energy coming into the system from upstream is dissipated when it reaches the reservoir. [0] - Yes, step 1 is to convert the gravitational potential energy into kinetic energy, so you can be pedantic and say you are actually harvesting kinetic energy. However, this is not the kinetic energy in the pre-existing flow.