Evaluation of Historical Sediment Deposition 



existed. Stream crossings were unrestricted, 

 culverts were used infrequently, and "cordu- 

 roy" roads were constructed across wet areas 

 simply by clearing the trees and then placing 

 timbers, side by side, across the wetlands, cre- 

 ating a road bed. These and other timber-related 

 activities, including construction of the rail- 

 spur, likely were major causes of enhanced 

 erosion and sediment transport to surface wa- 

 ters. 



The situation likely was compounded by 

 large stream flows in the catchment during the 

 spring of 1932 and 1933 (Schaffer and Engelter 

 1973). Comparatively low sedimentation rates 

 following the large flood of 1 894 suggest mini- 

 mal increases in sediment deposition in the lake 

 from an undisturbed watershed. However, high 

 stream flows in the early 1930s likely acceler- 

 ated the erosion and transport of sediment from 

 areas disturbed by various logging-related ac- 

 tivities in the watershed. 



The correlation between logging activities 

 and increased sedimentation in the early 1930s 

 is striking and leaves little doubt concerning a 

 cause and effect relationship between these two 

 events. Thereafter, lake sedimentation rates 

 declined in the mid to late 1930s in concert with 

 declines in timber harvest activity . 



During the mid- 1930s the Civilian Conser- 

 vation Corps (CCC) completed a road in the 

 Whitefish Lake watershed which extended 

 around the east side of the lake and up through 

 the Swift Creek drainage. This road was used 

 extensively for log hauling and appears to be the 

 only other significant human-related land dis- 

 turbance activity which may have affected 

 sedimentation during the 1930s. However, the 

 amount of land disturbance caused by the CCC 

 road was small in comparison to area impacted 

 by the network of roads, skid trails, and railspur 

 used in the timber harvest efforts. The 1937 fire 

 also may have contributed to sedimentation 

 during this period. However the impact of this 



fire is believed small, due to the limited aerial 

 extent of the fire (750 acres), and the fact that it 

 left no visible ash layer in the lake sediments 

 (unlike the ash layer corresponding to the 1926 

 fire). 



During the 1940s there was little timber 

 harvest or road building activity in the catch- 

 ment. Concurrent with the decline in timber 

 harvest and associated activity, sedimentation 

 rates in the lake declined to 42.5 mg/cmVyr. A 

 road was built in the Whitefish Lake watershed 

 up to the Big Mountain ski resort in 1947. 

 Although there has been considerable develop- 

 ment at the ski area, the vast majority of this 

 activity is located in the Haskill Creek drainage, 

 which is outside the Whitefish Lake Basin. 



Logging and associated road building ac- 

 tivity in the Whitefish Lake watershed com- 

 menced again in earnest in 1948, primarily on 

 the Stillwater State Forest in the Swift Creek 

 drainage. Harvest activities peaked around 1950, 

 declined again, and then increased through the 

 mid- 1 960s. This pattern of logging activity was 

 correlated with similar changes in lake sedi- 

 mentation (see Figure B-1). Lake sedimenta- 

 tion rates peaked at 72 mg/cmVyr around 1950, 

 declined to 52 mg/cm7yr in the mid 1950s, and 

 then increased over a ten year period, peaking at 

 87.8 mg/cm7yr in the mid-1960s. 



During the two decade period from the late 

 1940s through the 1960s, timber harvest and 

 accompanying road and skid trail construction 

 occurted across large parts of the watershed on 

 Stillwater State Forest Lands, and beginning in 

 the early 1960s on Burlington Northern lands. 

 During the first part of this time period, activi- 

 ties were concentrated on the gently sloping 

 valley bottoms. However, by the 1960s harvest 

 and associated road building activities had 

 moved up into steeper, more erosive areas. This 

 twenty year period of timber harvest and asso- 

 ciated activity appears cortelated with sediment 

 deposition in Whitefish Lake. 



Page 26 



Flathead Basin Cooperative Program Final Report 



