Hydropower is the most often used renewable energy
The first step in a hydroelectric dam is allowing the water to flow through the pipes until it reaches a special pipe called the scroll pipe, (a curly pipe). From there it comes to a series of gates called wicket gates, (Rotating gates allowing to be opened and closed) they are controlled by a governor that sets how far apart they are which limits and allows the amount of water that can get through. After this it arrives at a funky shaped turbine that optimizies the amount of spin it gets from water. The energy then converts to the axel( runner) after that it comes to a wheel witch have a circle of electromagnetic magnets. These are charged by an exciter witch brings a d.c current from the power grid. The wheel has a copper wire around it and the magnetic field of the magnets charges the wire witch goes on the power grid.
A fish ladder is when the dam has a set of stairs to the side of the dam so that fish can migrate to the other side of dams to lay there eggs. They know to hop up the stairs because the dam gives off a water current that attracts the fish.
Hydropower is not common in the midwest because the rivers and lakes are to shallow. They are mostly in Oregon and Washington. The biggest dam is the Coulee dam in Washington.
The reason for fishladders is because if they were not there the dam would block the fish from migrate.
The down sides to having dams are that silt can build up dehind it and lakes do not refresh themselves.
Hydropower is almost free and it doesn't use any waste but the dam costs around 20 billion dollars to make