Note the samples for year 2001 have been gathered but the data was unavailable to the author at the time 

 of this report. 



Modeled Water Yield Increase 



R1 WATSED is a computer model used to predict water yield increase from forest vegetation 

 manipulation. The model has evolved from the procedure discussed in Forest Hydrology, Hydrologic 

 Effects of Vegetation Manipulation, Part II (U.S. Forest Service 1978), and WATBAL a model 

 developed on the Clearwater National Forest (Patten 1989). 



It should be noted that R1 WATSED calculates the estimated water yield over a fully forested condition. 

 This is not the true natural condition for the headwaters area in Big Creek that have areas of rock 

 outcrop, and wetlands. Results from R1 WATSED are that the estimated percent water yield over 

 natural conditions is 9% or less for the five subwatersheds of Big Creek as well as the entire Big Creek 

 drainage (Big Mountain Ski and summer Resort EIS, 1995). Once modeled water yield increase 

 approaches 10% then field examination, Pfankuch stream stability ratings, cross-sections, Wolman 

 Peeble Counts, and RSI data are used to assess a stream channel's ability carry additional water yield 

 increase without major stream erosion. 



Wolman Pebble Counts/ Stream Cross-sections 



Wolman pebble counts (Wolman 1954) is a quantitative field procedure for determining particle size 

 distribution of the stream bed materials. This procedure however takes all size materials into 

 consideration as compared to the McNeil core methodology. In 1997 two stream reaches in Big Creek 

 were sampled using this procedure. At the same time a stream cross-section was done at the same 

 location. A high width to depth ratio and lack of pools is symptomatic of an unstable stream channel, 

 and in some cases a large amount of bedload in the drainage. There has not been reference reach 

 data for Wolman pebble counts and stream cross-sections of comparable stream size developed yet, to 

 compare these data from Big Creek to. However, the initial Big Creek data can be used as part of the 

 initial monitoring data set that is proposed later in this report. 



Following the Moose Fire eight additional stream reaches in Big Creek were sampled using these two 

 procedures. 



B.3.2 - Key Indicators 



The impainnent of Big Creek is described as partially supporting the beneficial uses of aquatic life 

 support and cold-water fishery, due to siltation and habitat alteration. Field examination, qualitative, 

 and quantitative stream monitoring confimn that the source of sediments is from a combination of 

 natural and man-caused upland and stream channel erosion. 



The long-term goals for Big Creek to improve the current situation are the following: 1) To reduce the 

 sediment sources, thereby reducing sedimentation loading and in turn reducing the effect of 

 sedimentation on fishery habitat within Big Creek. 2) To concurrently with sedimentation reduction, 

 mimimize any increase in short-term water yield increase, and to foster long-term reductions in water 

 yield increase so that the Big Creek stream channel can achieve dynamic equilibrium. And 3) Insure 

 proper revegetation and reforestion occurs within the Moose Fire area. 



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