Pros
Cheap - Existing hydroelectric plant can produce electricity at a cost of $0.0035/kWh or between $0.015/kWh to $0.08/kWh for new construction.

Clean - Hydroelectric power uses water as its fuel, which puts no harmful emissions or chemicals in the air or water.

Constant Power - Hydroelectric power is generated by moving water, which takes advantage of the constant flow of water in rivers and other waterways.

Demand Matching - Impoundment plants can better match electricity demands by using generated electricity to pump water into the reservoir during periods of low electricity demand and release it to generate additional capacity during high demand periods. Similarly, it could also be used to add peaking power plant capacity.

Recreation - Impoundment plants can add recreational opportunities to area communities by offering a calmer body of water, which could be used for a combination of activities such as fishing, boating and swimming.

Local - Many locations around the world have access to hydroelectric-capable water supplies.

Low Ongoing Costs - Once built, hydroelectric plants have very low operating costs. Hydroelectric also requires few replacements over its long life, as there are few parts to a hydroelectric plant (concrete walls and pipes and a turbine).

Modular - Hydroelectric plants can be customized to fit water availability. Small systems can be set up to power a house or farm or scaled up in size at large sites as a commercial power plant.



Cons
Droughts - Low water levels and droughts can negatively impact the amount of electricity generation capacity. These low levels can also effect the surrounding habitats.

Aquatic Movement - Impoundment plants can prevent fish from moving upstream by the dam and downstream by the turbines. To accommodate, fish ladders and an open area in the dam can allow fish movement.

High Construction Cost - Impoundment plants have high capital costs due to the construction of the dam, which creates a longer payback period resulting in larger hurdle for construction approval.

Relocation - The installation of a dam could require humans and animals living near the reservoir construction area to move.