5. WATER QUALITY, QUANTITY AND DISTRIBUTION: 



Identify important surface or groundwater resources. Consider tfie potential for violation of ambient water 

 quality standards, drinking water maximum contaminant levels, or degradation of water quality. Identify 

 cumulative effects to water resources. 



INTRODUCTION 



WATER QUALITY 



Timber harvesting and related activities, such as road construction and site preparation/scarification, 

 can lead to water-quality impacts by increasing the production and delivery of fine sediment to 

 streams. Construction of roads, skid trails, and landings can generate and transfer substantial 

 amounts of sediment through the removal of vegetation and exposure of bare soil. In addition, 

 removal of vegetation near stream channels reduces the sediment-filtering capacity and may reduce 

 channel stability and the amounts of large woody material. Large woody debris is a very important 

 component of stream dynamics, creating natural sediment traps and energy dissipaters to reduce 

 the velocity and erosiveness of stream flows. 



WATER YIELD 



Timber harvesting and associated activities can affect the timing, distribution, and amount of water 

 yield in a harvested watershed. Water yields increase proportionately to the percentage of canopy 

 removal, because removal of live trees reduces the amount of water transpired, leaving more water 

 available for soil saturation and runoff. Canopy removal also decreases interception of rain and 

 snow and alters snowpack distribution and snowmelt, which lead to further water-yield increases. 

 Higher water yields may lead to increases in peak flows and peak-flow duration, which can result in 

 accelerated streambank erosion and sediment deposition. 



ANALYSIS METHODS 



SEDIMENT DELIVERY 



Methodology for analyzing sediment delivery will be completed using a sediment-source inventory. 

 All roads and stream crossings were evaluated to determine sources of introduced sediment and 

 compliance with applicable BMPs. 



WATER YIELD 



An analysis of water-yield increases will not be completed for the proposed project. The project 

 proposal involves the salvage of trees killed, or in imminent danger of being killed, by forest insects 

 and diseases. As a result, water-yield increases have already occurred or will occur through natural 

 processes, and the proposed project would not contribute to the removal of live vegetation or 

 subsequent water-yield increases. 



ANALYSIS AREA 



WATER QUALITY 



The analysis will cover all stream segments within the proposed project area and all forest roads 

 within and leading into the project area. The project area is located within the Cilly Creek 

 watershed. 



EXISTING CONDITIONS 



REGULA TORY FRAMEWORK 



Montana Surface Water Quality Standards: According to ARM 17.30.608 (2)(a), the Swan River 

 drainage and its tributaries, including Cilly Creek, are all classified as B-1 . Among other criteria for 

 B-1 waters, no increases are allowed above naturally occurring levels of sediment, and moderate 



Page CEA-8 Checklist Environmental Assessment 



