\ /River Dunham Creek 



V / 



A hierarchical assessment of bull trout spawning areas in the Blackfoot River basin: 

 A baseline for identifying potential spawning areas -. ■ 



Introduction 



Substrate composition, cover, water quality and quantity are important elements 

 for salmonid spawning. The amount and suitability of stream substrate for spawning also 

 varies by valley morphology, stream size (order) and species (Bjomn and Reiser 1994, 

 this study). Developing a better understanding of bull trout spawning areas is particularly 

 relevant due to the ESA "threatened" status of bull trout and the discrete nature of the few 

 existing known spawning areas within the Blackfoot Watershed. In order to foster a 

 better understanding of local bull trout spawning requirements and pursue methods to 

 identify potential spawning areas, we assessed four existing fluvial bull trout spawning 

 areas at various spatial scales. The study was undertaken in a physiographic region 

 dominated by glacial valleys and high basin relief Our objectives were to characterize 

 properties of spawning areas at the regional, reach and spawning site spatial scales. 

 Study implications relate to the identification and assessment of historical spawning areas 

 within comparable settings, evaluations of emergent fiy survival, the monitoring and 

 correction of anthropogenic sediment-producing activities. 



Study area 



The study area included ^ ciearwater - . 



four spawning streams (Copper 

 Creek, Dunham Creek, Gold 



Creek and Monture Creek) that V / y Monture creek 



originate from two glaciated 4. / . ^copper creek 



mountain blocks, separated by - ^ .^ ^ ^ 



, _,, _. , Gold Creek _. , ,_ 



the Clearwater River, and / i "••-,.»>. - K-i&' >v, '.' 



located in the northern region -J, . .*7- ..'--' ~' :^- j 



of the Blackfoot Watershed ^. / , ^"^^'""^^Biackfoot River 



(Figure 53). Most local ' ^ 



streams in this area originate in " -', •"•*.'{-/ 



high (sub)alpine basins of Belt 



rock geologic origin. Most of 



the larger streams begin in 



cirques and flow south in 



glaciated U-shaped valleys through coniferous sub-alpine and montane forests. 



Significant portions of the region are roadless or managed for wilderness, except west of 



the Clearwater River where a majority of the land is largely managed as private industrial 



forest. These streams generally exit the mountains as larger, colder tributaries of the 



Blackfoot River. 



Methods 



We characterized regional physiographic features using ecoregion and valley-type 

 classification (Omnerick 1988; Rosgen 2002), perennial stream-order calculations 

 (Strahler 1957) and landform interpretation from 1:24:000 topographic maps. At the 

 reach scale, we quantified channel morphology using modified level II surveys at each 



69 



Figure 53. Bull trout spawning area survey study area. 



