LOWER WEST FORK PROJECT

FINAL ENVIRONMENTAL IMPACT STATEMENT

Bitterroot National Forest

West Fork Ranger District

July 2010

Lead Agency: USDA Forest Service

Responsible Official: Julie K. King 

Forest Supervisor

Bitterroot National Forest

 1801 North 1st Street

Hamilton, MT 59840 

 

For Information Contact: Dave M. Campbell 

West Fork District Ranger 

Bitterroot National Forest 

6735 West Fork Road 

Darby, MT 59829 

(406) 821-3269 

Copies of this Final Environmental Impact Statement are available in compact disc (CD) format at 

the West Fork Ranger District at the address above and can be viewed at the Bitterroot National 

Forest’s web site: http://www.fs.fed.us/rl/bitterroot/projects/

Abstract: This Final Environmental Impact Statement (FEIS) describes the effects of 

implementing three alternatives in the Lower West Fork analysis area on the West Fork Ranger 

District of the Bitterroot National Forest. The analysis area includes the Wildland Urban Interface 

(WUI) along the West Fork of the Bitterroot River (West Fork River). The Bitterroot Community 

Wildfire Protection Plan identified this area as a high treatment priority. Soil, watershed, and 

fisheries management needs were also identified in the analysis area. The four purposes and 

objectives of this project include: 

1. Reduce Fuel Loads and Crown Fire Hazard in Low Elevation Forest 

Reduce the potential for stand-replacing crown fires in and adjacent to the WUI. This will provide 

more fire management options in the event of unplanned ignitions and allow the return of frequent, 

low intensity surface fire to which the low elevation forests are adapted in the Lower West Fork 

analysis area.

2. Improve Forest Resilience to Natural Disturbances, Particularly the Ponderosa Pine 

Component 
In the absence of disturbance, specifically surface fire, the low elevation ponderosa pine forests 

have experienced shifts in composition and structure. Historically, frequent, low intensity surface 

fire maintained ponderosa pine on the drier, low elevation sites by killing the seedlings and 

saplings of more shade tolerant tree species and creating seedbed conditions that favored ponderosa 

pine regeneration. In the absence of fire, the proportion of shade tolerant trees has increased and 

ponderosa pine regeneration has decreased. Thinning in the drier ponderosa pine forests removes 

the shade tolerant understory and increases crown spacing between the larger ponderosa pine in the 

overstory. This treatment will reduce stocking and the potential for crown fire. It will improve the 

health and vigor of the large pines, and their ability to resist insect and disease attacks and survive 

fires. 

3. Maintain or Increase the Shade Intolerant Forest Component, Especially Ponderosa Pine 

The dry, low elevation forest is a well- to over-stocked mixture of ponderosa pine and Douglas-fir 

with increasing levels of Douglas-fir regeneration in the understory. Thinning these forests from 

below would open the canopy and retain the mature ponderosa pine component. These conditions 

would favor ponderosa pine regeneration, which is well-adapted to these sites. Ponderosa pine 

with sufficient growing space is resistant to insects, disease, and fire, and would be resilient to 

environmental changes. 

4. Improve Overall Soil, Watershed, and Fisheries Conditions

Sediment and temperature modification have caused the Montana Department of Environmental 

Quality to list the West Fork River as impaired. This project identified road segments that 

contribute sediment to streams and culverts that block fish passage and isolate populations. The 

Interdisciplinary Team reviewed these roads and culverts and identified the roads no longer needed 

for resource management. Reducing sediment contributions from these roads would improve water 

quality in the West Fork River and bring it closer to being delisted. Removing or replacing 

culverts blocking fish passage would restore genetic exchange between fragmented bull trout and 

westslope cutthroat trout populations. Genetic exchange would improve the genetic diversity of 

the fish stocks and their resilience to changing environmental conditions. 

Three proposed commercial thin units have soil conditions that are near or exceed Region 1 Soil 

Quality Standards. In addition, the analysis area contains approximately 297 acres of terrace 

plantations. The soils on the terrace benches are highly compacted. Subsoiling and/or leaving 

coarse woody debris on these soils would accelerate soil rehabilitation. 

Alternative 2, the Proposed Action, would treat approximately 5,056 acres; Alternative 3 would treat 

approximately 3,599 acres. About 84 percent of the treatments are in the WUI in Alternative 2; about 94 

percent are in the WUI in Alternative 3. Both sides of the West Fork River would be treated using 

commercial thinning and prescribed fire in Alternative 2. In Alternative 3, most of the treatment areas are 

on the west side of the river. The terrace plantations would be treated on both sides of the River in 

Alternative 3, as would the non-commercial thin units. Both alternatives would reduce fuels and thin trees 

to improve stand resiliency to fires, insects, and disease. Both alternatives would generate some revenues 

that could be used for stewardship projects. However, neither alternative would generate enough revenue 

to complete all the resource opportunities identified.

Forest Plan amendments are proposed for Alternative 2 and 3 related to coarse woody debris, thermal 

cover, and elk habitat effectiveness.

Alternatives 2 and 3 are not expected to have significant negative impacts on issues identified through 

scoping. Analysis shows all issues were resolved through project design or the use of common mitigation 

measures.