B. Analysis Methods 



In order to address the issues with water quality as described in Chapter 1, instream sediment and 

 upland sources of sediment will be discussed. 



1. Upland Sources of Sediment 



A sediment source inventory was completed in 2000 for sources on State managed land 

 within the channel and outside of the channel. Roads and stream crossings were 

 evaluated to determine existing sources of introduced sediment. 



2. Instream Sources of Sediment 



The methods applied to the project area to evaluate potential instream sediment 

 production include the Rosgen Stream Classification (Rosgen, 1996) and the R-1 Channel 

 Stability Rating (Pfankuch, 1975). The tools were deemed the most appropriate to 

 provide information on stream channel form, function and resistance to change. This 

 information indicates the relative stability of a stream. The measure of risk for additional 

 instream sources of sediment will be annual water yield. This stability of a stream 

 channel is an important indicator of where a threshold of concern for annual water yield 

 should be set. Thresholds were established based on evaluating the acceptable risk level, 

 resource value, and watershed sensitivity. 



The water-yield increase for the watershed in the project area was estimated using the 

 Equivalent Clearcut Acres (ECA) method as outlined in Forest Hydrology, Part II (1976). 



In order to evaluate the watershed risk of water yield increase effectively, a threshold of 

 concern for each watershed was established. Thresholds were established based on 

 evaluating the acceptable risk level, resources value, and watershed sensitivity. 

 Watershed sensitivits' was evaluated usins auali^^^""^ 2cc<:»cctr!Pntc qo w^n qc ucincr 

 procedures outlined in Forest Hydrology Part II (1976). As water yields increase as a 

 result of canopy reduction, the amount of water flowing in a stream gradually increases. 

 The more stable streams are more likely to handle larger increases in water yield before 

 they begin to erode, while less stable streams will have a greater potential to experience 

 erosion at more moderate water yield increases. 



3. Cumulative Effects 



Water yield will be disclosed as a cumulative effect in the Existing Conditions portion of 

 the hydrology analysis because the existing condition is a result of all past harvestmg and 

 associated activities. 



An analysis of the potential for adverse cumulative watershed effects to occur due to 

 increased sediment delivery and increased water yield resulting from the proposed action 

 was completed for the project area. The analysis included: 1) An estimate of potential 

 water yield increases using the ECA method described under existing conditions; 2) An 

 evaluation of existing channel conditions; 3) An inventory of existing roads, and 4) An 

 evaluation of proposed road and harvest unit location and mitigation. 



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