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CUMULATIVE WATERSHED EFFECTS IN THE SEQUOIA NATIONAL FOREST 



Summary of Oral Testimony Before the 

 House Committee on Natural Resources 

 9 March 1994 



G. Mathias Kondolf, Ph.D. 

 2241 Ward St, Berkeley, CA 94705 



Qualifications 



I am an Assistant Professor of Environmental Planning at the 

 University of California at Berkeley, where I teach courses in 

 environmental geology, hydrology, stream restoration, and 

 environmental planning. I was awarded a Ph.D. in Geography and 

 Environmental Engineering from the Johns Hopkins University, a 

 Masters of Science in Earth Sciences from the University of 

 California at Santa Cruz, and a Bachelor's in Geology (cum laude) 

 from Princeton University. My research centers on sedimentation 

 and hydrologic processes relevant to management of aquatic 

 habitat and other natural resources. I have published over 

 seventy technical journal articles, book chapters, and technical 

 reports, and I speak frequently at professional meetings on these 

 topics. 



CuanilativB Watershed Effects 



Cumulative watershed effects (CWEs) refer to effects of land 

 management practices on water, water quality, aquatic habitat, 

 and other hydrologic resources that move off-site and accumulate 

 downstream. These effects may be synergistic, interacting in 

 complex ways so that the total impact exceeds the sum of 

 individual impacts. These synergistic effects cannot be 

 addressed on a site-specific basis, but require study of the 

 entire watershed to identify cumulative effects. 



Timber harvest and road-building can reduce the rate of 

 interception and infiltration, resulting in increased runoff for 

 a given rainfall or snowpack. Roads can alter natural drainage 

 patterns, concentrating runoff into a fewer number of channels. 

 Erosion can result from the increased runoff, and from direct 

 effects such as tree removal and decay of roots, from 

 undercutting of slopes by road construction, and from other site 

 disturbance during timber harvest. 



The cumulative effects of timber harvest can be evident 

 miles downstream of the harvesting itself and may persist for 

 decades. For example, in Redwood National Park, the redwood 

 grove containing the tallest trees in the world continues to be 

 threatened with bank erosion as a result of the influx of 



