FLOOD11726

• Designation Number: 77
• County: Boulder
• Community: Longmont
• Basin: South Platte
• Title: FIS - Longmont
• Date: 1/1/1977
• Designation Date: 7/27/1977
• Floodplain - Doc Type: Historic FEMA Regulatory Floodplain Information

FLOOD INSURANCE STUDY

1.1

1.0 INTRODUCTION

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1.2

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Purpose of Study

The purp9se of this Flood Insurance Study is to investi-
gate the existence and severity of flood hazards in the
City of ~ongmont, Boulder County, Colorado, and to aid
in the administration of the Flood Insurance Act of 1968
and the Flood Disaster Protection Act of 1973. Initial
use of this information will be to convert the City of
Longmontlto the regular program of flood insurance by
the Federal Insurance Administration. Further use of
the information will be made by local and regional plan-
ners in their efforts to promote sound land use and flood
plain development.

Coordination

The City:of Longmont Engineering Department supplied zon-
ing and Gorporate boundary maps and various detailed
drawings tfor channel improvements such as final construc-
tion pla~s for the Spring Gulch Linear Park and storm
drainageifacilities, dated January 1973, and the struc-
tural pl~ns for the Pratt Street bridge, over the St.
Vrain Cr~ek. The Longmont Planning Department has sup-
plied a ~opy of The St. Vrain Comprehensive Plan (Ref-
erence l), which describes the comprehensive plan for
what is dalled the Prime Urbanized Area of Longmont.
! . .
The Planq~ng Department also prov~ded a copy of the flood
plain and floodway zoning ordinance, and various histori-
cal aspeqts of flooding and community development. Con-
ferences [were held with the City Planning and Engineer-
ing Depa~tments staff on July 23, 1974; May 14, 1975;
and Dece~ber 30, 1975, to discuss detailed aspects re-
garding ~he various streams studied.
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The Omaha District of the U.S. Army Corps of Engineers
provided :contour mapping on the St. Vrain Creek and
parts of !Left Hand Creek, Dry Creek, and Spring Gulch
(Referende 2). Computer card input regarding the hydro-
logy and [hydraulic analyses for the St. Vrain Creek and
Left Hand Creek were also provided by the U.S. Army
Corps of (Engineers. The Flood Plain Information Reports
complete~ by the U.S. Army Corps of Engineers in January
of 1969, on Left Hand Creek and in June of 1972, on the
Lower St':1 Vrain Creek, served as an important basis for
compariso!n in this study (References 3 and 4). On
October 1:6, 1974, a conference was held with the Omaha

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