FLOOD10328

• County: Boulder
• Community: Lyons
• Stream Name: North Saint Vrain and Saint Vrain Creeks
• Title: Floodplain Information Report, North Saint Vrain Creek, Saint Vrain Creek, Floodplain Update, Town of Lyons, Boulder County, Colorado
• Date: 6/1/1998
• Prepared For: Lyons
• Prepared By: BRW, Inc
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Floodplain Information Report
K:\35600\004\FLOODPLAIN INFORMA nON REPORT. doc

June

998

Floodplain Information Report
K:\35600\004\FLOODPLAIN INFORMA nON REPORTdoc

June

998

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GLOSSARY

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BIBLIOGRAPHY

SECTION 5 - INTERPRETATION AND USE OF REPORT DATA
5.1 Flooding Frequency and Discharge Table
502 10- and 50-Year Flood Events
503 100-Year Flood Event
5.4 500- Year Flood Event
5.5 Flooded Areas
5.6 Flood Elevations
5.7 Horizontal and Vertical Control Monumentation

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Technical

Figure 1 through 6: Flood Profiles

Plates 13 through 19: "North St. Vrain Creek Upstream of Lyons and St. Vrain Creek
Downstream of Lyons, Boulder County", Town of Lyons Floodplain Mapping, 100-Year
and 500- Year Floodplains

Appendix

(HEC-RAS Summary Printout

Data with Computer Disks)

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SECTION 4 - HYDROLOGIC AND HYDRAULIC DETERMINATIONS
4.1 Flood Characteristics
4.2 Hydrologic Analysis
403 Hydraulic Analysis

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Plate 2:

Index Map

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PIa te 1

Basin Map

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APPENDICES

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SECTION 2 - STUDY AREA DESCRIPTION
2.1 Drainage Basin Characteristics
2.2 Climate
2.3 Study Reach Description

SECTION 3 - HISTORY OF FLOODING

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Table 7A:

Figure:

BRW Benchmark Information

Lyons Benchmark Location Map

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SECTION 1 - INTRODUCTION
1.1 Authorization
1.2 Background
1.3 Purpose and Scope
1.4 Acknowledgements
1.5 Related Flood Studies

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Table 7:

North St.

Vrain - St.

Vrain Creek: Benchmark Information

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Table 6:

Flood Frequency-Elevation and Discharge Data

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Table 5

Roughness Coefficients

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Table 4:

Peak Discharges at Selected Locations

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PREFACE

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Table 3

USGS Gaging Stations

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LIST OF TABLES

Page
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Table 2:

Historical

Flood Peak Discharges and Stages, St.

Vrain at Lyons

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Table 1

Summary of Culvert/Bridge Information

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North St. Vrain & St.
Floodplain Update

Vrain Creeks

TABLE OF CONTENTS

Town of Lyons

North St. Vrain & St.
Floodplain Update

Vrain Creeks

LIST OF TABLES AND FIGURE

Town of Lyons