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The Mountain-Prairie Region


U.S. Fish and Wildlife Service
134 Union Boulevard
Lakewood, Colorado 80228





October 13, 2006 

Q.  What is the primary effect to bull trout from the proposed Rock Creek Mine? 

A.  The main effect to bull trout from the proposed Rock Creek Mine is degradation of spawning and rearing habitat due to sedimentation during the initial 5-year construction period and for two years afterward.  Even with measures to minimize sediment entering Rock Creek, some amount of sediment will find its way into the creek and reduce the quality of the habitat by despoiling clean spawning gravels and fill pools and foraging areas.  The effect is anticipated to subside about two years after the construction is done as the sediment is eventually flushed from the creek and the revegetated areas adjacent to the affected stream reach begin to recover.    

Q.  What will be done to minimize or mitigate the effects to bull trout? 

A.  Measures will be employed during construction to avoid or reduce sediment from entering the creek.  Silt fences, straw bales, sediment barriers, geotechnical fabric, slash filter windrows, and other “best management practices” will be employed when working near the creek or instream.  All necessary erosion prevention and control measures will be employed during activities that have the potential to deliver sediment to the creek such as installation of culverts and bridges.  Revegetation of areas disturbed by mining activities and/or road construction will be done to establish vegetative cover to prevent erosion and sedimentation.  In addition, during and after construction of the mine site and associated access roads, continuous monitoring of sediment input will be conducted in order to detect increases in sediment loading in the creek, identify the source of the sediment input, and implement correction actions. 

Monitoring of water quality and water chemistry would be required by Revett in order to detect changes in stream flows, stream temperatures, and heavy metal contamination that may affect bull trout.  If monitoring shows an elevated risk to bull trout, the Service would request re-initiation of consultation to address the issue. 

Q.  What were the Court’s concerns regarding the remanded biological opinion? 

A. The  Court was concerned about how the Service determined that the bull trout was not jeopardized by the proposed mine when in previous jeopardy analyses the Service indicated that the loss of a subpopulation of bull trout could cause jeopardy.  Another Court concern was how the Service determined the status of bull trout rangewide in light of the numerous previous biological opinions that have been issued. 

Q.  How were the Court’s concerns addressed in this biological opinion? 

A. The Service did a better a job of explaining how it conducted a jeopardy analyses by clarifying what units of analyses are considered and the step-by-process that leads to the jeopardy determination.  Also, it provided additional information and discussed in detail how we analyzed the previous biological opinions as well as how it considered the most recent information to determine the status of the species not only rangewide but at the local level. 

Q.  How does the proposed Rock Creek mine affect bull trout critical habitat? 

A. There are five sections of bull trout critical habitat in the Rock Creek watershed.  The function of these critical habitat units for bull trout will be diminished somewhat during the construction period and for two years afterward due to the anticipated effects from sedimentation.  However, the reduction in habitat quality will be temporary and not expected to destroy or adversely modify habitat components that are essential to conservation of the species. 



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