I need to make a clarification about a statement I made in my letter to the editor regarding Randy Udall and Auden Schendler’s column on the Castle Creek hydro regarding “run of the river” (“More questions about Aspen hydro plant,” March 2, The Aspen Times).
A “run of the river ” hydroelectric facility, as I mentioned, uses the free flow and gradient of a river for the generation of power. They don’t normally use a large reservoir, such as Glen Canyon’s Lake Powell does. Still, run of the river projects can have impoundments, or reservoirs, and they aren’t always small.
The real idea behind a “run of the river” project is just that, to use the natural flow of a stream, unaltered, to generate power. Run of the river doesn’t remove the water from a stream completely, as the Castle Creek project does to Maroon Creek. Nor does it usually remove the water for a significant distance as will happen with Castle Creek. That was the point I was trying to make.
The Castle Creek hydropower project will seriously alter the flows of both Castle and Maroon creeks. It will use the natural flow of the streams, but not in the benign and environmentally friendly way implied by the term “run of the river.” Water will be taken out of the streams, diverted a considerable distance to Thomas Reservoir, and then released at a much greater gradient than either Castle or Maroon Creeks to power the turbine. In this sense Glen Canyon is closer to a real run of the river hydro project. While it uses a large reservoir, alters the flow of the Colorado River and runs water through the turbines with greater force than the natural flow would, it at least leaves the water in the river.
Calling the Castle Creek hydro project “run of the river” sounds good, but is still very misleading and not altogether true.