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• Board Meeting Date: 1/23/2008
• Description: ISF Section - Injury with Mitigation - Case No. 3-99CW34; application of Charles E. Nearburg
• Board Meetings - Doc Type: Memo

Draft - Trout Creek Bioassessment

Only one of the CWCB criteria is met at the 35 cfs CWCB recormnended summer flow level.
Under a reduced flow of 31 cfs the water level. in the channel drops 0.13 feet and the criterion
met at 35 cfs is still met at the reduced flow.

In summary, un-rehabilitated channel conditions at Station 1 do not allow CWCB criteria
standards for winter or srunmer to be met. Average velocity is the only criterion met, and it
continues to be met under the proposed reduced flows.

Station 2

Station 2 represents riffle conditions after rehabilitation. It can be seen ill F:igures 3 and 4 that
channel conditions present in tbis rehabilitated section of the stream are very much improved.
Channel consolidation has reduced braiding so that a single flow channel exists at higher flows
and only two flow channels exist at lower flows. Table 5 summarizes the flow characteristics of
the channel at this location under both CWCB minimum instream flow levels and flow levels
reflecting the proposed 4 cfs diversion. The effect ofthe proposed diversion on flow levels in
the channel can be seen graphically in Figures 3 and 4. As a result of habitat rehabilitation,
CWCB criteria are more likely to be met and criteria that are not met remain close to theCWCB
standards.

Table 5

Effect of 4 cfs Diversion on CWCB Instream Flow Criteria

. Station 2 ,u__,_,. __'_W.."L ..............
(Top Width at Bankfull ;;; 45.0 ft.)
(Wetted Perimeter at Bankfull ;;; 46.6 ft.)
;c"'.... Depth Velocity Wetted Perimeter
Characteristics Characteristi cs Characteristi c:s
Average % of %of Average %of %of % Wetted % of % of
Depth (ft.) CWC~ Station 1 Velocity (fl/sec.) CWCS Station 1 Perimeter ewcs Station 1
(CWCS Criteria Reference (CWCB Criteria ;;; Criteria Reference (CWeS Criteria Reference
. . Criteria :;;0.45 ft.) 1_0 ft.1sec.) Value . Criteria;;; 53 %) Value
., €lJrrent CWCB
. lnstream Row OA3 96 159 1.01 101 75 76% 143 155
Right 15 cis
DiSCharge after
Proposed 0.37 82 137 0.91 91 69 70% 132 189
Diversion: 11cfs
: yurrent ewcs
': Instream Flow 0.69 153 177 1.37 137 80 81% 153 131
: Right 35 cfs .
8ischarge after
Proposed 0.64 142 173 1.31 131 79 81% 153 135
Diversion: 31 cfs
_. .__ r_ .. .

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. F:\WWEWEI\2D00\981-143\Bioassessment\Final Report\Report.doc