184 



dilution, dispersion, and storage reduce the impacts of management 

 activities downstream of the managed watersheds . . . [but under some 

 conditions] ...downstream effects may be more dramatic than on-site 

 effects. . . 



Forest management practices have dramatically improved water 

 quality protection by using riparian management areas and by 

 recognizing and protecting high hazard sites. Riparian areas on 

 National forests, as well as state and private lands, are now 

 managed to protect water quality and stream habitat conditions. 

 This includes providing shade, avoiding disturbance by equipment, 

 and some retention of trees for recruitment to the stream of large 

 woody debris. Studies show that stream temperature increases are 

 avoided and suspended sediment increases minimized by the use of 

 riparian zones (4) . 



Watershed damage can also occur where high hazard sites are 

 not recognized. Landslides are an important process in sediment 

 delivery to streams and potential channel damage (5) . An inventory 

 in the Siskyou National Forest by Amaranthus et al. found that 76 

 percent of the landslide volume came from only 9 percent of the 

 land area (6) . Two studies show that recognition of hazards can 

 result in improved performance. In the Waldport Ranger District, 

 Barnett found that reduced road landsliding in recent years appears 

 to be a result of "...improved road-building techniques, better 

 enforcement of contract specifications, and a reduction in miles of 

 roads built each year" (7) , MacMillian Bloedel in British Columbia 

 found that landslides from roads were actually less frequent in 

 steep areas than areas of moderate gradient, probably due to more 

 caution in road construction and design (8) . 



IV DAMAGE OFTEN ASSOCIATED WITH PAST PRACTICES 



Observations of watershed damage are often associated with 

 past practices rather than current practices. In California I 

 visited a timber harvest plan in the Sierra Nevada where channel 

 damage had resulted from channel diversions and skidding through 

 the channel in the 1960 's (prior to the implementation of the 

 Forest Practices Act) . This sites was eventually approved for 

 harvesting with management measures to improve the stream 

 conditions and reduce future sources of sediment resulting from the 

 past activities (9) . 



A recent study of landslides in the Deschutes Watershed in 

 Washington, near Olympia, found that most of the landslides 

 experience during a 100+ year storm were from roads greater than 

 15-years old (10) . "The majority of the problems occurred because 

 of steep cutslopes and block culverts." Recommendations for 

 maintenance and corrective actions can be developed from these 

 types of inventories. In the Mapleton Ranger District or the 



Siuslaw National. Fore'5^ unstable sidecash Tnaterial fx^.L. ■.. >!.> 



creates a potential for landslides. This type of road construction 

 would not be allowed today for these types of conditions. The 



