In one way or another, I have been involved with hydro-electric power for practically all of my life (a story for another time!)
Hydro is a very economical method of generating electricity, particularly in a “run of the river” type situation, where no dam is required. Also, a hydro plant can last for centuries . For example, No.4 turbine in New Zealand’s Lake Coleridge hydro electric station was commissioned in October 1914, and is still spinning now (good old British Thompson-Houston, they made things to last!)
Hydros are not as damaging to the environment as your friends the Greenies would have us believe, either. In fact, there are instances in which hydro electric development has actually enhanced the environment. (For example, the Upper Waitaki project in New Zealand’s South Island, in which over three quarters of a million trees were planted in what was formerly a treeless, semi-arid part of the world.