Small hydro is the application of hydroelectric power on a commercial scale serving a small community or medium sized industry. A generating capacity of up to 10 megawatts (MW) is becoming generally accepted as the upper limit of what can be termed Small hydro, although this may be stretched to 25MW and 30 MW in Canada and the USA. In contrast many hydroelectric projects are of enormous size, such as the generating plant at the Hoover Dam (2,074 megawatts ) or the vast multiple projects of the Tennessee Valley Authority.

Hydroelectric power is the technology of generating electric power from the movement of water through rivers, streams, and tides. Water is fed via a channel to a turbine where it strikes the turbine blades and causes the shaft to rotate. To generate electricity the rotating shaft is connected to a generator which converts the motion of the shaft into electrical energy.

Small hydro is often developed using existing dams or through development of new dams whos primary purpose is river and lake water-level control, or irrigation. A small-scale hydroelectric facility requires a sizeable flow of water and a reasonable height of fall of water, called the head.

Small hydro can be further subdivided into mini hydro, usually defined as less than 1,000kW, and micro hydro which is less than 100kW. Micro hydro is usually the application of hydroelectric power sized for a single family or small enterprise.

List of small installations

• Snoqualmie Falls