FLOOD09052

• County: Routt
• County: Moffat
• Basin: Yampa/White
• Title: Dam Failure Floodplain Information for the Yampa River Downstream of Stagecoach Reservoir
• Date: 12/1/1989
• Prepared For: Moffat County / Routt County
• Prepared By: CWCB
• Floodplain - Doc Type: Flood Documentation Report

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The additional discharge to be added to the
computed flow through the breach is therefore

,

30,900 + 32,400 = 63,300 cfs.

The additional volume to pass through Lake
Catamount coming from Stagecoach reservoir was
estimated by subtracting the volume of the flood that
fills the freeboard storage space in Lake Catamount
plus the volume that escapes through the spillways from
the total volume coming from Stagecoach, or

v. = 33,275
= 33,275
= 21,376

- {(18,900 - 7,422) + 421}
- { 11,487 + 421 }
acre-feet

Using these parameters, the dam failure hydrograph
at Lake Catamount was computed to, have the' following-'
characteristics:

v,
qp
tb

= 40,276
= 127,251
= 7.66"

acre feet
cfs
hours

The Yampa River downstream of Lake Catamount dam to
Sunbeam in unincorporated Moffat County was divided
into ten stream reaches. The stream reaches were shown
in the schematic diagrams, and the trapezoidal valley
cross section data used to typify each reach was shown
in Table 2.

The results of the DWR model analysis are summarized
in Table 3. Since the routed peak discharge at the end
of reach 13 was approximately equal to the estimated
peak discharge of the 100-year flood, the analysis was
not continued beyond this point.

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