Creek basin were some short reaches of G stream type on the glacial terrace escarpments. Figure - 6 

 displays the distribution of the Level -1 Rosgen Stream Types. 



Rosge 



Figure 6 

 n Stream Types 



Mooflel 

 Uke 



Lake 



ktaal 



Mudr 



V 



>, 



Natural Disturbance Processes 



Erosional Disturbances 



Current surface erosion rates are low or non-existent in undisturbed portions of the watershed. Soil 

 erosion occurs where the surface soil has been exposed by disturbances, either natural or man caused. 

 These disturbances are concentrated on roads, landings, and skid trails associated with timber 

 management. The amount of soil erosion on these disturbed sites depends on the soil type, the slope 

 steepness, and the amount of residual vegetation remaining on the site after the management activity. 

 It also depends on the type of erosion control features applied after the soil was disturbed. Waterbars, 

 revegetation, and spreading of debris all reduce soil erosion and with time can eliminate erosion. 



Within Big Creek mass failures are a minor erosional process. A few inactive mass failures are 

 mapped in the Big Creek drainage. They probably occurred after the glaciers receded when there was 

 an abundance of water and little or no vegetation to stabilize the slopes. Most active or recent mass 



16 



