FLOOD00374

• Designation Number: 146
• County: Chaffee
• Community: Unincorporated Chaffee County
• Stream Name: Lower South Arkansas River
• Title: Floodplain Information Report - Lower South Arkansas River
• Date: 4/1/1979
• Designation Date: 12/1/1979
• Floodplain - Doc Type: Floodplain Report/Masterplan

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6. Preparing a technical addendum containing pertinent data related
to the hydrologic and hydraulic analysis.

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of Poncha Springs. The study reach included herein begins at the downstream

limit of this adjoining report. The transitional area has been carefully

coordinated between reports so that flood flow estimates and floodplain

delineations are compatible and continuous. Copies of the adjoining report

are for sale upon request at the offices listed in the preface of this report,

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7. Preparing a floodplain information report.

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1. Five reproducible mylar planimetric-topographic map sheets with
a contour interval of 2 feet and a scale of 1" = 200'.

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Flood hazard boundary maps were published for Chaffee County by the

Federal Insurance Administration (FIA) in June 1977. This mapping, with a

scale of 1 inch equal to 2000 feet, shows general areas of flooding along

the major streams in the unincorporated areas. The FIA maps do not include

topographic information and are intended for use in the Emergency Flood Insur-

ance Program. The emergency maps are not based on detailed studies, After

designation and approval of this report by the Colorado Water Conservation

Board, Chaffee County will be able to ammend the emergency maps. The detailed

information in this report may then be submitted to FIA for conversion to the

Regular Flood Insurance Program,

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Mapping and Surveys

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Chaffee County in cooperation with the Colorado Water Conservation

Board obtained recent topographic maps for this study. This mapping was

prepared by Delta Aerial Surveys, Inc. under a separate contract.

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Specific topographic data provided to the consultant includes:

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2. One set of 9" x 9" black and white photographic contact prints;
date of photography: May 9, 1978.

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3. One set of Xl and GR cards (HEC-2 Computer Program) for 65
digitized cross sections of the South Arkansas River Valley.
A printout of the digitized cross sections was also supplied.

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The items listed above are available at the Colorado Water Conserva-

tion Board. Reproducible mylars for the topographic maps with a scale of

1" = 200' are available at Chaffee County offices. Additional field surveys

were performed by Water Resources Consultants, Inc. and Colorado Water

Conservation. Board personnel to obtain bridge and culvert opening sizes

and to verify the aerial mapping.

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Related Flood Studies

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Water Resources Consultants, Inc. prepared a floodplain information report

dated March 1978, for the South Arkansas River and Poncha Creek in the vicinity

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