FLOOD08620

• Designation Number: 463
• County: Boulder
• Community: Longmont
• Basin: South Platte
• Title: FIS - Longmont, CO, Boulder County
• Date: 9/1/1987
• Designation Date: 5/1/1998
• Floodplain - Doc Type: Floodplain Report/Masterplan

of the flood plain and floodway zoning ordinance, and various
historical aspects offlooding and, community development. Meetings
were held with the City Planning and Engineering Departments staff
on July 23, 19741 May 14, 19751 a~d December 30, 1975, to discuss
detailed aspects regarding the st~eams studied.

The U,S. Army Corps of Engineers ,(COE), Omaha District, provided
mapping of the St. Vrain Creek anb parts of Lefthand Creek, Dry
Creek No, 1, and Spring Gulch (Re~erence 6). Computer input
regarding the hydrology and hydraulic analyses for the St, Vrain
Creek and Lefthand Creek were also provided by the COE. The
flood-plain information reports completed by the COE in January
1969 for Lefthand Creek (Reference 7) and in June 1972 for Lower
St. Vrain Creek (Reference 8) served as an important basis for
comparison in this study. On Oc~ober 16, 1974, a conference was
held with the COE to gather addi~ional information on Longmont and
to review potential problems.

.

The U,S. Geological Survey (USGS) was contacted to obtain historic
floodflow data (References 9, 10, and 11). Maps of flood-prone
areas, prepared by the USGS, showing approximate flood plain de-
lineations at a scale of 1:2,400 'were also reviewed (Refer-
ence 12).

At a meeting on August 27, 1974, jattended by representatives of
the urban Drainage and Flood Control District, FEMA, and Gingery
Assoc-iates, Inc., study reachesiand methods for the initial study
were decided. An additional meeting was held on January 24, 1975,
in Washington, D.C. to further clarify the purpose of the study
and the methods used for flood plain delineations.

Other agencies and individuals contacted for background infor-
mation included the CWCB, the Co+orado Highway Department, the
Longmont Daily Times-Call newspa~er. Private citizens of Longmont
were also interviewed regarding past floods, high-water marks, and
flood damage.

A final community coordination meeting for the initial study was
held on January 7, 1976, by the planning Department of the City of
Longmont.

;
In April 1985, FEMA authorized the reV1Slon for the City of
Longmont to incorporate the afor~mentioned floodplain information
reports (References 1-4).

On August 5, 1986, the results of the revised study were discussed
at the final community coordinat~on meeting, which was attended by
representatives of FEMA, the studY contractor, and the community.
All significant problems raised at that meeting have been
addressed in this study,

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