D.2 Dealing with Uncertainty 



There are two areas of future uncertainty that could affect the reduction of pollutants and/or the 

 rehabilitation of Big Creek. First, a major peak stream flow event could cause additional streambank 

 erosion along portions of the streambanks. A peak flow event could be the result of a severe rain storm 

 event, a rain on snow event, or a major peak flow snow melt event. The proposed road decomissloning 

 and old skid trails waterbarring/revegetation would significantly reduce the impact of any future peak 

 flow event, by reducing the efficiency of the road and ditches in routing water to the streams. This 

 reduced runoff efficiency would, therefore, decrease the actual quantity of water during a peak flow 

 event and result in less ditch and chanel erosion; therefore, less sediment load to Big Creek. 



The other type of natural or man-caused event that could affect the restoration plan would be additional 

 wildfire. As described earlier, wildfire is a major disturbance process that operates in these forested 

 watersheds. The Moose Fire is expected to have significant effects to the vegetation and stream 

 conditions in lower Big Creek for many years. The natural forest fuels loading from dead and down fuel 

 materials are quite high, for the higher elevation sites in upper Big Creek. These fuel loads are outside 

 the natural range of variability for alpine sites. This fuel loading is caused by a combination of fire 

 suppression and tree mortality from blister rust. The area around Big Mountain has a very high density 

 of natural fire starts due to lightning. The combination of the fuel loading and the fire start potential 

 makes upper Big Creek a prime candidate for a major wildfire. This uncertainty cannot be planned for 

 in this restoration plan; however, there may be fuel reduction activities proposed in the future in Big 

 Creek could reduce the hazard. Where fires and other catostrophic events occur, it will be necessary to 

 ensure that recovery is not hindered in a manner that significantly increases sediment loading, causes 

 significant negative stream habitat impacts, or increases the period of time needed for recovery to full 

 support of cold water fish and associated aquatic life. 



The restoration plan for Big Creek in theory attempts to maximize as much as possible, reductions in 

 sediment sources, enhanced revegetation potential, and reduced water yield from road systems. 

 Because of this proposed restoration plan, an additional increase in pollutant reduction to insure a 

 safety margin for future uncertainty does not appear necessary. This is because the proposed actions 

 are not only expected to meet percent fines and streambank erosion objectives (targets) discussed in 

 Section C, but are also expected to result in conditions that are significantly better than required to 

 ensure full support of cold water fish and associated aquatic life In Big Creek. Pursuing conditions that 

 are significantly better than established targets allows for future flexibility in forest management 

 decisions and accounts for the continued existance of a limited road system with some allowance for 

 some future additional management activities consistent with existing forest plans. These management 

 activities may include road BMP improvements, culvert resizing, road decommissioning, and post-fire 

 salvage logging. 



An additional margin of safety will also be ensured by the proposed monitoring program (See Section 

 F), wherein the monitoring results will be reviewed to observe trends relative to sediment loading. If the 

 monitoring results do not demonstrate a trend towards reduced sediment loading and achievement of 

 the proposed targets, actions will be taken to identify the source of the continued loading and remedial 

 actions will be defined (assuming that the continued loading is attributable to anthropogenic causes). 



D.3 IVIanagement Practice Selection 



There were seven pollution situations described In section B.3.2 Pollutant Source Inventory. All seven 

 situations are addressed entirely or to some extent within the proposed pollutant reduction treatments. 

 The treatments proposed are based upon Montana Water Quality BMP's, scientific literature (e.g. road 

 reclamation), and past professional experience of the stakeholders in implementing similar practices In 



36 



