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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

Table 6

Effect of 4 cfs Diversion on CWCB Instream Flow Criteria

Station 3
(Top VVidth at Bankfull = 55.54 ft.)
(Welted Perimeter at Bankfull = 57.46 ft.)
Depth velocity Wetted Penmeter
Characteristics Characteristics Characteristics
Average % of %of Average % of % of % Wetted % of % of
Depth (ft.) ewcs Station 1 Velocity (fUsee.) CWCS Station 1 Perimeter CWCS Station 1
(CWCS Criteria Reference {CWeS Criteria = Criteria Reference (CWCS Criteria Reference
Criteria =0.56 ft.) Value 1.0 ft./sec.) Value Criteria = 58 "/0) Value
Current ewcs
lnstream Flow 0.60 107 222 1.34 134 100 34% 59 69
Right 15 cis
Discharge after
Proposed 0.51. 91 189 1.20 120 91 '32% 55 86
Diversion: 11 cfs
Current ewcs
lnstream Flow 0_78 139 200 1.59 159 92 51% 88 82
Right 35 ds
Discharge after
Proposed 0.83 152 224 1.66 166 101 41% 71 68
Diversion: 31 cis

Note: Caution should be used when interpreting data at Station 3 since it is a meander channel and does not fit CWCS 1996 guidelines
for using riffle habitat to evaluate minimum instream flow requirements.

Under the 15 cfs CWCB "Winter instream flow two CWCB criteria are met as a result of habitat
rehabilitation. This compares to one criterion met at Station 1 at this flow. Under a reduced
flow of 11 cfs the water level in the charmel drops 0.12 feet 2nd one criterion continues to be
met. A second criterion rem~s close to the CWCB standard. More importantly, average depth
is significantly better than conditions seen at Station L ~~ ~ .~-

At the 35 cfs CWCB recommended summer flow level two CWCB criteria are met as a result of
"". habitat rehabilitation. This compares to one criterion met at Sta,tion 1 at this flow. Under a

,
reduced flow of 31 cfs the water level in the charm.el drops 0.13 feet and two of the" criteria
continue to be met.

In summary, CWCB criteria are more likely to be met as a result of the rehabilitation work. In
addition, when met they are IDet to a greater degree. Criteria that are not met are close to the
CW<:;:B standards and better than pre-existing conditions.

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