FLOOD00328

• County: Eagle
• Community: Eagle
• Stream Name: Eagle River
• Title: Hydrology Report Roaring Fork and Eagle Rivers
• Date: 12/1/1997
• Prepared For: Eagle County
• Prepared By: J.F. Sato & Associates
• Floodplain - Doc Type: Floodplain Report/Masterplan

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FEMA - REGION VIII
LIMITED MAP MAINTENANCE PROGRAM (LMMP)
EAGLE AND PITKIN COUNTIES, COLORADO
HYDROLOGY REPORT

I. INTRODUCTION

PUI:pose. Authorization. and Scope

The hydrologic investigations described in this report have been performed by I.F. Sato and
Associates (JFSA) to review and update previous Flood Insurance Study/Flood Insurance Rate Maps
in unincorporated areas of Eagle and Pitkin Counties as part of FEMA's 1997 Limited Map
Maintenance Program (LMMP) in Region 8. The studied flooding sources are the Roaring Fork and
Eagle Rivers,

JFSA's current contract with FEMA-Region 8 calls for updating FIS flood hazard data for
communities within Region 8 specified by FEMA in individual Task Orders. This Task Order
includes two river reaches in unincorporated areas of Eagle and Pitkin Counties. The hydrologic
investigations were undertaken to establish peak flood flow rates on two specific river reaches.

The scope of the studies included in this Task Order were discussed in the Time and Cost (T&C)
meeting held in the Town of Eagle, CO, on November 4,1996, A brief description of each reach
and the type of study for each reach follows. The study area is shown on Figure 1, Vicinity Map.

Stream Reaches Included in this Task Order

Roaring Fork River Reach - Detailed study of an eight-mile reach that extends
approximately from the Eagle/Garfield county line at the downstream end, to the State Highway 82
bridge near Wingo at the upstream end. As shown on Figure I, the study reach is located
approximately midway between the USGS stream gaging station near Aspen and the GJenwood
Springs gaging station. The only nearby communities include the small towns of Wingo and Basalt
located on the upstream portion of the reach.

The study reach is shown in more detail on Figure 1-1 obtained from available USGS Quad sheets
to the scale of 1"=2000'. The alignment of SH 82 shown on Figure I-I has been substantially
modified. Approximately 2.5 miles of SH 82 have been relocated to the south or left bank of the
upper portion of the Roaring Fork River reach. Two new bridges were constructed as part of this
highway relocation. The hydraulic analyses using new aerial mapping will take these changes into
account. Per FEMA's designation of a detailed study, the hydraulic analyses for this reach will
include preparation of flood profiles for the 10-, 50-, 100-, and 500-year peak discharges, and
delineation of the 100- and 500,year floodplain boundaries.

Eagle River Reach - Limited-detail study of a seven,mile reach of the Eagle River from the
Town of Gypsum upstream to the Town of Eagle, This study reach is shown also on Figure I and
in more detail on Figure 1-2.

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