internal agency scoping and public involve- 

 ment (Beaver Lake Collaborative). 



In general, high-risk segments are those that 

 are positioned adjacent to or u^ithin 200 feet of 

 lakeshore riparian-habitat areas; are steep, 

 entrenched and actively eroding (gullying); 

 and are constructed in draw bottoms. The 

 lakeshores, in particular, being high-recre- 

 ational-use areas, have been encroached upon 

 by general recreationalists building unautho- 

 rized roads, trails, boat launch pads, camp- 

 sites, and pit toilets. Although other issues, 

 such as safety and access, were also used to 

 identify these high-risk areas, these were 

 deemed the most appropriate in terms of 

 addressing potential impacts to water quality 

 and riparian wetland habitat. 



Upland roads generally lack adequate road 

 drainage features in the project area. As a 

 result, numerous segments are rutted, gullied, 

 and highly entrenched. However, since there 

 are no discemable channels capable of trans- 

 porting sediment to Beaver Creek, the only 

 perennial streams in the analysis area, these 

 segments pose a low risk to water quality. 



SOILS 



INTRODUCTION TO 



AFFECTED 



ENVIRONMENT 



ANALYSIS AREA 



The Beaver Lake Project area lies approxi- 

 mately 4 air miles northwest of Whitefish, 

 Montana, and includes all or portions of 

 Sections 7, 8, 16, 17, 18, 19, 20, 21, 28 and 29, 

 Township 31 north. Range 22 west. The 

 topography is glacially influenced, with 

 predominantly broken ground, cliffs, draws, 

 benches, and pothole lakes ranging in eleva- 

 tion from 3,000 and 4,000 feet. There are 6 

 lakes in the area: Beaver, Murray, Little Beaver, 

 Woods, Dollar and Rainbow. 



GEOLOGIC HISTORY AND 

 PARENT MATERIAL 



The surficial landforms found in the Beaver 

 Lake Project area have resulted from a com- 

 plex and diverse geologic history dating back 

 to the formation of the Rocky Mountain 

 Trench, and, more recently, continental and 

 valley glaciation. The predominant rock types 

 exposed throughout the project area are 

 referred to as the Belt Supergroup and were 

 formed over six-hundred-million years ago. 

 These slightly metamorphosed, sedimentary 

 rocks were formed from sand, silt, clay, and 

 carbonate material deposited in the great 

 shallow Belt Basin which existed in this area in 

 Precambrian times (600 to 1,400-million years 

 ago). Over time, compressive forces, along 

 with burial and compaction, altered the physi- 

 cal and chemical composition of the material 

 deposited in the Belt Basin, resulting in the 

 formation of sedimentary rocks, sandstones, 

 shales, and siltstones. 



The formation of the Rocky Mountain Trench 

 is dated to around 65-million years ago when a 

 thickening of the continental crust occurred in 

 Oregon and Washington as the Pacific sea- 

 board collided with an island arc in the Pacific 

 Ocean. At this convergent margin, compres- 

 sive forces caused deformation, uplift, and 

 consequent faulting of the Belt Supergroup, 

 forming local compressional features that 

 include large northwest/southeast trending 

 folds. 



The project area was influenced by glacial 

 activity throughout the Pleistocene Era (10,000 

 to 1.8-rrullion years ago). Glacial activity had 

 considerable influence on the location and 

 character of surface materials throughout the 

 Stillwater State Forest. In general, steeper 

 sideslopes (30% to 40%) were scoured of 

 glacial tills, while more moderately and gently 

 sloping topography was blanketed with deep 

 till and glacial outwash deposits. Glacial 

 activity formed 2 main landforms: 



• Water-influenced topography - occurs in 

 low-relief, low-elevation areas (valley 

 bottoms). The lakes found in the valley 

 bottoms are formed in kettles and pot- 



m-3ir 



Stillwater State Forest • Beaver Lake Timber Sale Project 



