Evaluation of Historical Sediment Deposition 



(5) Results from the three study lakes 

 suggest that roads represent the great- 

 est disturbance activity resulting in 

 increased fine sediment transport and 

 deposition in the downstream lakes. 

 Once constructed, the sediment contri- 

 bution appears to decline. 



(6) Changes in deposition of fine sedi- 

 ments directly attributed to natural 

 stream banks, floods, fires, and other 

 natural erosion processes during the 

 past 150 years were much smaller that 

 changes attributed to human distur- 

 bance activities in these two water- 

 sheds. Previous speculation that ero- 

 sion of naturally unstable stream banks 

 and other natural sources may mask 

 sediment inputs attributed to human 

 activities appear unfounded with re- 

 spect to fine sediment deposition in 

 Whitefish Lake, Swan Lake, and Lake 

 McDonald. 



Flathead Basin Cooperative Program Final Report Page 39 



