FLOOD06836

• County: Grand
• Community: Winter Park
• Stream Name: Fraser River
• Basin: Colorado Mainstem
• Title: Hydrology Report for Winter Park FIS
• Date: 1/4/1984
• Prepared For: Winter Park
• Prepared By: J.F. Sato & Associates
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Hydrology Report
for
Winter Park Flood Insurance Study - FEMA
by
J.F. Sato and Associates

Background

The Town of Winter Park commissioned a flood study of the
Fraser River and several tributaries in 1980. The study was
performed by Worrall and Associates, Inc. of Winter Park. It
included a detailed hydrology study for the Fraser River Basin.
The Worrall analysis used data from eight U.S.G.S. gages
(Table 1) to develop flood discharge vs. drainage area curves for
several recurrence intervals. Seven of the gages are in the
Fraser basin and one is in the nearby Williams Fork basin
(Figures 1 and 2). All the gage records are affected by
diversions.
First, records of Denver Water Board diversion amounts on the
dates of peak annual flows were obtained. The diversion flows
were added to the U.S.G.S. record peak flows (Figures 3 to 6 and
Exhibit 1). These combined flow annual peaks were analyzed
according to the log-Pearson Type III procedures described by the
Water Resources Council in Bulletin 17. Flood flows for the
2-year, 10-year. 50-year, 100-year, and sOO-year recurrence
intervals were calculated for all the gages (Figures 7 to 13).
These values were then used for the final regression curves
(Figure 14).

Snowmelt Peak Flow Analysis

To check the assumption of snowmelt peak flows, the month in
which annual peaks have been recorded were summarized (Table 2)
and strip charts were examined.

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