BOARD01695

• Board Meeting Date: 7/25/2006
• Description: ISF Section - Injury with Mitigation Proposal - Case No. 5-04CW238 - Application of S.G. Company
• Board Meetings - Doc Type: Memo

biological and hydrological value the only reasonable source of water available for this project is the
Blue River. S.G. Company considered the alternative of ceasing diversions into the
Oxbow/Floodplain Fish Habitat Improvements should such diversions reduce the flow of the Blue
River below the decreed ISF amount. S.G. Company has concluded that that alternative is not
reasonable from an environmental perspective because it would substantially reduce the benefits to
the environment and aquatic biota of the Blue River that are supported by the Oxbow/Floodplain
Fish Habitat Improvements. That alternative is also not feasible from an economic perspective
because it would substantially reduce the economic value of the Oxbow/Floodplain Fish Habitat
Improvements to the point where construction and long-term operation and maintenance of the
project would not be feasible. Accordingly, S.G. Company has concluded that no other reasonable
alternative exists to provide full protection to the ISF. The mitigation proposed herein will allow
the diversion of water to the Oxbow/Floodplain Fish Habitat Improvements while continuing to
preserve the natural environment to a reasonable degree.

Scientific Justification for the Proposed Mitigation:

Overview:

The Blue River Fish Habitat Improvements were based on a professional assessment, design, and
permitting process. Queen of the River Consultants completed a representative fluvial assessment
of the Blue River in 1999 that included development of a database on channel morphology, flow
estimation, trout habitat assessment, quantitative fisheries data, quantitative macroinvertebrate data,
stream health estimation based on biotic condition indices, and a review of historic flow information
for the Blue River. The purpose of this initial analysis was to provide a definition of existing
conditions, to provide a database to compare changes after restoration was completed and to
demonstrate how the proposed mitigation will enable the CWCB to continue to preserve and
improve the natural environment of the affected stream to a reasonable degree in spite of the
potential injury from diversion into the Oxbow/Floodplain Fish Habitat Improvements. The results
of the 1999 analysis were as follows:

Results of Pre-Restoration Samplin2:

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Length of channel- 18,500'
Channel Types- C3c, F3
Bankfull Widths- 100-133'
Bankfull Mean Depths- 1.6-3.3'
Bankfull Max Depths- 2.09-3.46'
Width/Depth Ratios- 37.73-60.18
Flood Prone Widths- 136.8-376.0'
Entrenchment Ratios-1.l-3.0
Channel Stability Ratings- fair-good
Trout Habitat Ratings- fair

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