Application of the Sequoia Method 



Table H-2. Extent of Activities — Equivalent Acres 



Activity 



Tractor Clearcut 

 Cable Clearcut 

 Tractor Partial-cut 

 Cable Partial-cut 

 Mechanical Site Prep. 

 Mechanical Release 

 Abandoned Roads 

 Rec. & Admin. Sites 

 Perm. Skid System/landings 

 Bums 

 ORV Trails 

 System Roads 



Equivalent Acres 



Harvested Acres 

 Harvested Acres 

 Harvested Acres 

 Harvested Acres 



Treated Acres 



Treated Acres 

 Miles X 2 Acres 



Acres of Sites 

 Harvested Acres x 27% 



Acres Burned 

 Miles x 1.5 Acres 

 Miles X 3.5 Acres 



age of about eight percent of the watershed in 

 1989. 



Sequoia was similarly applied to the 30 

 smaller watersheds located within the Flathead 

 Basin. Cumulative Runoff Acreages in these 

 critical fisheries ranged from percent in Elk 

 Creek and Lion Creek to over 30 percent in 

 Freeland Creek. In addition to Freeland Creek, 

 Cumulative Runoff Acreages in Jim Creek, 

 Fish Creek and Sheppard Creek were above 

 Sequoia's 12 percent threshold of concern. The 

 Squaw Creek tributary and Hand Creek are 

 approaching the threshold. (See Table H-3.) 



The Flathead National Forest and the Mon- 

 tana Department of State Lands currently use 

 similar water yield models (H^OY), based on 

 the Equivalent Clearcut Area (ECA) concept. 

 Rather than measuring compaction and soil 

 exposure in anticipation of changes in peak 



discharges, the ECA models measure canopy 

 removal in anticipation of changes in average 

 annual water yield. In the Flathead Basin, it is 

 assumed that channels with "normal" stability 

 can withstand an increase of ten percent in 

 annual water yield. The ECA and the CRA 

 model predictions should be correlated — you 

 can't remove canopy without soil compaction 

 and exposure. Nevertheless, the models meas- 

 ure different impacts and have different under- 

 lying assumptions. 



The ECA model was applied to the same 30 

 critical fisheries watersheds as Sequoia, and in 

 the same rank order Freeland, Fish and Shep- 

 pard Creeks were judged to be above the thresh- 

 old of concern. The ECA model did not, how- 

 ever, find Jim Creek, the Squaw Creek tributary 

 or Hand Creek to be at or near the threshold. 

 Hopefully, these results, when compared and 



Flathead Basin Cooperative Program Final Report 



Page 107 



