Soil Nutrient Loss -_The heat of the wildfire will also affect the nutrient status of some of the soils. The 

 soils that experienced high burn severity are generally the most affected. These soils are most 

 susceptible to nutrient loss by either: 1) volatilization during the fire, 2) potential post-fire soil erosion, 

 and 3) loss by leaching. 



There is expected significant increase in nutrients (nitrogen and phosphorus) delivered from the fire 

 area, into the streams. This increased water nutrient level can probably be tracked into the North Fork 

 River, but probably not beyond the confluence of the Flathead River. Increases from past fires, such as 

 Red Bench, were measured on the order of 2-3 fold. This increase should not be a problem for the 

 aquatic systems within or just outside of the fire. 



Ctiannel Effects - Following the fire many of the stream bottoms were examined in the field and It was 

 the interpretation of the soil scientist/vegetation specialist that the riparian shrub component was still 

 viable and would reestablish rapidly on the majority of the burned streams. This is especially true for 

 the flatter, low elevation mainstem stream-bottoms along Big Creek. However, several of the steeper, 

 deeply incised perennial and ephemeral stream bottoms on Demers Ridge, and the unnamed 

 drainage east of Skookoleel Creek burned with high or moderate burn severity. In these areas the 

 natural re-vegetation of shrubs and trees is going to be significantly reduced for several years. This 

 makes these draws very susceptible to channel erosion and debris torrents, with the right type of 

 stonn and/or snowmelt event. 



Big Creek is a large Rosgen "C" channel with a well-developed floodplain and high width/depth ratio. 

 Large woody materials were common across the floodplain, especially along the channel margins. 

 This gives it a wide area for "storage" of products from upland or in-channel erosion. Most sediment 

 from upstream should settle out in this area, leaving only minor amounts of the finer sediment to travel 

 downstream, and then probably only during the peak flow period. 



Water Yield Increase Effects - Extensive literature exists indicating that stream flows are increased after 

 fires, through a combination of evapo-transpiration reduction, soil-surface storage reduction, and 

 snowmelt modification. This is particularly true in watersheds where moderate and high fire severity 

 occurs. The magnitude of the increase has been variable in different study watersheds, but an 

 increase always occurs. 



The modeled water yield increase from historic timber management was done in 1 996 for Big Creek. 

 Results from R1 WATSED are that the modeled percent water yield over natural conditions is 9% or 

 less for the five sub-watersheds of Big Creek as well as the entire Big Creek drainage. Depending 

 upon the channel stability, water yield increases in the 10-15% range may cause increased channel 

 erosion. Both the annual water yield as well as the peak flow yield is expected to increase significantly 

 in lower Big Creek due to the effects of the wildfire. The annual water yield increase is initially 

 estimated (professional guess, no modeling completed as of this date) to be between 5 to 10 percent 

 above pre-fire level for Big Creek at the mouth. The water yield increase and/or peak flows in the 

 smaller mid/high elevation burned tributaries to Big Creek, could individually be greater. This is due to 

 decreased response time of streamflow increases following rain events, because of the lack of a duff 

 layer. 



This increase in water yield has the most potential to cause short-term increases in channel erosion in 

 several of the small tributary streams to Big Creek. This is due to the burning riparian vegetation and in 

 some case large woody debris within the streambanks, along with the naturally erodible streambank 

 materials, and the post-fire increased water yield. Along the mainstem of Big Creek there is some 

 potential for increased streambank erosion in the destabilized reach (below Elelehum Creek and above 



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