Study of logging's impact on Oregon streams shows no water temperature increase on state forest lands, slight increase on private timber

By Eric Mortenson, The Oregonian 

Published: Wednesday, September 21, 2011, 2:49 PM     Updated: Wednesday, September 21, 2011, 3:22 PM

View full size 

The Oregonian/fileCattle grazing on Forest Service land tromp through Camp Creek, a John Day drainage stream full of steelhead trout. 

 

An on-going study of Oregon Coast Range streams before and after logging shows no average water temperature increase on state forest lands but a 1.3 degree increase on private land, according to an Oregon State University researcher.

The study involves 33 sites in the Coast Range. Water temperature was monitored for two years before harvest and for five years after logging. All of the monitored streams are fish-bearing; stream temperature is critical to cold-water fish such as trout and salmon.

Jeremy Groom, an OSU research associate and lead author of the report, said the study does not address whether the temperature increase on private land is significant. The state Department of Environmental Quality says logging and other forest management work should not increase stream temperatures by more than 0.5 degrees.

Research from previous decades, when loggers sometimes cut trees and burned slash to the edge of streams, showed water temperature increases ranging from 3 to 21 degrees.

Groom said the current results will be presented to the Oregon Board of Forestry in November. The board oversees application of the Oregon Forest Practices Act, which governs such things as buffers zones that must be left adjacent to streams when logging occurs.

State forest managers typically leave larger buffers than required by the forest practices act, and leave more standing timber than required, according to an OSU summary of the research.

While many private landowners follow similar practices, the study involved only those meeting the minimum requirements under the forest practices act. The research was intended to find out if those regulations are working.

"A big question is whether the temperature changes warrant any sort of rule changes," Groom said. "I supply (the board) with this information, but whether or not that's an important amount of temperature increase is not in my job description. I'm very curious to see what happens."

None of the studied sites is on federal national forest or Bureau of Land Management timber.

The research is a collaboration of OSU, the Oregon Department of Forestry, private industry and other state and federal agencies.

--Eric Mortenson