WATERSHED SCALE RESTORATION PLANNING IN THE BLACKFOOT RIVER WATERSHED, MONTANA

A primary beneficial use of the Blackfoot River and its tributaries is its cold water fishery. Several streams within this watershed do not currently support this beneficial use due to geomorphic and water quality degradation caused by logging, placer mining, grazing, and irrigated agriculture. In order to assess the nature and extent of this degradation, stream conditions have been quantified in terms of sediment production, channel morphology, riparian vegetation, nutrients, and water temperature. To achieve this, an initial aerial assessment of the entire watershed supported segmentation of streams based on geologic source area, topography, stream morphology, riparian vegetation, and land use. Stream segments were then grouped based on geology, climate, and topography to accommodate natural variability in background conditions. A sediment source assessment was performed to quantify sediment sources related to stream banks, roads, and upland environments, and to identify areas of accelerated anthropogenic sediment production. Geomorphic and aquatic habitat conditions have been quantified through field sampling of a series of representative reaches and statistically evaluated to identify least impaired channel conditions. Thermal impacts have been modeled using SNTEMP to highlight areas of accelerated thermal gain and to identify means of reducing stream temperatures in impacted reaches. A SWAT model helped quantify nutrient loading and assess restoration scenarios. Integration of the watershed-scale data collection and analysis has allowed the development of beneficial use support goals for impaired streams throughout the watershed. The achievement of these goals will be sought through implementation of both passive and active restoration activities that will be prioritized based on overall anticipated ecological benefit.