The weir at the top of the Sechelt Creek run-of-river power project has created a small head-pond, but the pond does not extend beyond the existing bed of the creek. No land has been flooded, and the change to sedimentation patterns is very limited.

Photo © Steven Earle

Most of the major problems associated with hydro-electricity projects are related to the construction of dams and the resulting flooding within the reservoir and changes in river dynamics.

A run of river hydro project does not have a dam and reservoir. In most cases the water is impounded behind a small weir and then channeled into a penstock (pipe) that transports it from the weir at a relatively high elevation, to the power station at a lower elevation.

The amount of electricity that can be generated depends on the flow rate (as controlled by the flow-volume of the stream and the diameter of the penstock) and the head (change in elevation). While some run of river projects are large (e.g., Niagara Falls), most are quite small—producing less than 50 MW.  (In contrast, a large dam/reservoir project typically generates 100s to 1000s of MW.  For example, the Revelstoke Dam generates about 1980 MW.)