FLOOD09431

• County: Statewide
• Community: State of Colorado
• Stream Name: All
• Basin: Statewide
• Title: Hydrologic Summary FlS State of Colorado
• Date: 4/1/1981
• Prepared For: FEMA
• Prepared By: Camp Dresser & McKee
• Floodplain - Doc Type: Educational/Technical/Reference Information

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supplemented the COE gage data with three additional years of flow records
and recomputed the peak discharges to check the COE results. It was found
that there is little change in the values of the discharges for the 10-,
50-, 100- and SOD-year recurrence intervals when the same procedure is
performed. This result is shown in Figure 6. It was therefore recommended
that the peak discharges developed in Reference 7 be used in the flood
insurance study of the Arkansas River at La Junta (refer to COM's letter to
FEMA and CWCB, June 4, 1980, contained in Appendix Bl. These flow rates
have also been summarized in Table 1.

City of Lamar, Colorado

The streams studied in the flood insurance study for Lamar, Colorado are
Willow Creek and the Arkansas River {see Appendix B for stream locationsl.
The literature search carried out for the City of Lamar flood study
included a review of the COE "Review Survey for Water Resource Development,
Lamar, Colorado and Vicinity, Hydrology," Revised in 1974 (Reference 61.
This report contained a detailed hydrologic analysis for Willow Creek and
the Arkansas River at Lamar. Peak discharges for the 10-, 50-, 100- and
SOD-year recurrence intervals were estimated.

The COE analysis of Willow Creek at Lamar utilized TM-l (Reference II, to
estimate the peak flow rates at various locations along Willow Creek. COM
reviewed the basin data calculated by the COE as well as the application of
Reference 1 and found no errors in the hydrologic computations. Due to the
short records of gage data for plains region streams tributary to the
Arkansas River, no attempt was made to check regional discharge

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