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

2.0 AREA STUDIED

2.1 Scope 0f Study

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This Flood Insurance Study encompasses the limits of the
Prime Urbanized Area of the City of Longmont as described
in TheiSt. Vrain Comprehensive Plan (Reference 1). The
area of the study is shown on the Vicinity Map
(FigurEp 1).

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In addition to the St. Vrain Creek, the four tributary
streamS included in this study are Dry Creek, Left Hand
, . .
Creek, ! Spring Gulch (The Slough), and Loomlller Basln.
Dry Creek, Spring Gulch, and Left Hand Creek originate
outsid~ the Prime Urbanized Area of Longmont in the Rocky
Mountain foothills and follow generally easterly courses
throug~ the city. Spring Gulch consists of an unimproved
channel which starts south of East 15th Avenue and con-
tinuesias a concrete lined channel through Spring Gulch
Linear'Park to 3rd Avenue, then down to the St. Vrain
Creek. i The Loomiller Basin is a depression oriented in
a nortmwest-southeast direction through the center of
Longmomt. Flood waters accumulate in the depression and
subseq~ently drain into Spring Gulch Basin near Third
Avenue:and Atwood Street. A large portion of the area
within , the Prime Urbanized Area limits and adjoining
the stfeams is fully developed. All of the defined
stream~ were chosen with consideration given to existing
hazards and forecasted development and construction
throug~ 1980.

The limits of detailed study in the Prime Urbanized
Area City of Longmont were determined by the Federal
Insurance Administration after consultation with the
commun~ty and the Study Contractor. In general, those
areas trhat are currently developed, or are expected to
be developed within the next 5 years, were studied by
detailed methods.

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2.2 Community Description

The City of Longmont is located about 38 miles north of
Denver; the state capital. The recorded history of the
Longmorit area dates back to the summer of 1820 when
Longmo~t's namesake, Major Stephen H. Long and his troop
of nineteen soldiers explored the St. Vrain Valley.
Prior no Long's arrival the Ute and Arapahoe Indians were
the vatley's only inhabitants. In the 1830s fur trappers
carne irito the area and built numerous trading posts and
forts ~long the South Platte River east of Longmont.

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