Small dams may take as little as one year to build and fill. Larger dams with hundreds or thousands of MW of installed capacity take several years to complete. If you are analyzing a dam with a very large reservoir, make sure to include the time it will take to fill with water and become completely operational. You may want to analyze the influence of construction delays on a project. A 1996 World Bank study found that power projects it had financed went over schedule by an average of 36%.

Read a World Bank technical paper on estimating construction costs and schedules.