Hydropower is produced by the movement of water rushing from a higher elevation to a lower elevation, which turns a turbine and creates electricity. Dams are used to hold back the water in order to create reservoirs. Water moves from these reservoirs to powerhouses by way of waterways, such as rivers and streams. Once at a powerhouse, the water generates electricity, which is then transported to the power grid. The system has the potential for large amounts of rushing water to be present at any given time, sometimes without warning, so it's important to use caution and learn to recognize warning signs.