Application of the Sequoia Method 



correlated with the other Cooperative studies, 

 will allow us to gain understanding of cumula- 

 tive watershed effects in the Flathead Basin. 



Summary 



The Sequoia Method for cumulative water- 

 shed effects risk assessment was chosen for use 

 in the Flathead Basin for a number of reasons. 

 The procedure is representative of the official 

 U.S. Forest Service Region 5 (California) pro- 

 cedures. This model or others similar in appli- 

 cation and data requirements are currently used 

 by the National Forests in Region 5. 



Sequoia is computationally straight-for- 

 ward. The most difficult obstacle is obtaining 

 all of the information on harvesting, site-prepa- 

 ration, and roads from the various land-owners 

 in mixed ownership watersheds. All of the data 

 required by Sequoia arc routinely maintained 

 by landowners. 



Finally, since Sequoia is an accounting sys- 

 tem for areal disturbances, it is actually compat- 



ible with our growing Geographic Information 

 Systems capabilities. All of the information 

 required by Sequoia is found on the Flathead 

 National Forest Geographic Information Sys- 

 tem (GIS). 



Just as Region 5 has made the CRA methods 

 official analysis tools, the Montana Cumulative 

 Watershed Effects Cooperative has made a 

 model much like H^OY the new "official" model 

 for Region 1 . The understanding in the coopera- 

 tive is that members will work with the new 

 model to resolve its shortcomings. Neverthe- 

 less, many of the ECA logic flaws will never be 

 worked out. The most critical of these is that 

 increases in average annual flow are related to 

 channel forming processes. Again, Sequoia is 

 an accounting system that does measure things 

 we know to be related to peak flows and channel 

 forming processes. We have begun working on 

 a computer version of Sequoia for use with 

 microcomputers. When it becomes available, 

 the model will be in a form easily usable by all 

 land managers in the Flathead Basin. 



Flathead Basin Cooperative Program Final Report 



Page 111 



