Title: Thermal pollution in rivers: Will adding gravel help to cool them down?
Author: Oliver, Marie; Grant, Gordon; Burkholder, Barbara;
Source: Science Findings 133. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 5 p.
Publication Series: Science Findings
Description: Thermal pollution in rivers can be caused by dams, logging, municipal wastewater treatment, and other human activities. High water termperatures stress ecosystems, kill fish, and promote disease and parasites, and so dam operators, timber companies, and municipalities are held responsible for thermal loading caused by their operations. These entities are looking for ways to mitigate environmental damage. When Portland General Electric (PGE) was applying for re-licensing of its extensive hydroelectric project on the Clackamas River in Oregon, questions were raised about whether the company's existing plans to improve fish habitat on the lower river by adding gravel into the channel to replace lost sediment would also help to bring maximum summer water temperatures within regulatory limits.
A study co-led by a PNW Research Station scientist provided critical information to PGE--and the 33 interested parties that signed off on its re-licensing agreement--about how river overall temperatures are affected as water flows through naturally occuring gravel bars. The research showed that although water emerging from gravel bars tends to be cooler than the main channel, gravel augmentation alone is unlikely to cool the whole river. It could still provide positive benefits, however, by increasing the number of cool spots for fish to hide during the hottest part of the day.
Based on science by Gordon Grant, and Barbara Burkholder
Keywords: thermal pollution, dam, hydroelectric, hyportheic zone, Clackamas River, Gordon Grant, Barbara Burkholder
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
- You may send email to firstname.lastname@example.org to request a hard copy of this publication. (Please specify exactly
which publication you are requesting and your mailing address.)
XML: View XML
Oliver, Marie. 2011. Thermal pollution in rivers: Will adding gravel help to cool them down? Science Findings 133. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 6 p.
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility