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The enlargement relations are based on the susceptibility of streams to incise and/or widen at an accelerated rate due to changes in flow, clear water discharge, direct disturbance and streambank erosion. Information needed for this assessment includes:

a) Summary of risk ratings from rural or urban flow increase
(Figures 72, 73, and 92)
b) Flow increase risk associated with reservoirs
(clear water discharge, ramping flows, etc.),
imported water, and diversions
c) Streambank erosion risk (Figure 78)
d) In-stream mining impacts (Figure 83)
e) Direct disturbance risk (Figure 96)
f) Stream type

The relations used to obtain risk for channel enlargement involves a summary of the risk ratings from all of the above, which are determined from Table 16, Figures 72, 73, 77 and 85, Worksheet 3a, and then summarized in Worksheet 4a (PDF, 52 kb, 1 p.). The combination of these risk scores are then stratified by stream type category for an overall risk rating (Figure 85).

Figure 85

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The results are again summarized individually by sub-watershed in Worksheets 5a & 5b and for multiple sites/sub-drainages in Worksheet 6.

Worksheet 5a: Printable PDF (10 kb, 1 p.) | Excel Spreadsheet (27 kb)
Worksheet 5b: Printable PDF (9 kb, 1 p.) | Excel Spreadsheet (35 kb)
Worksheet 6: Printable PDF (8 kb, 1 p.) | Excel Spreadsheet (21 kb)

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