FLOOD07310

• Designation Number: 467
• County: Boulder
• Community: Lyons
• Basin: South Platte
• Title: Floodplain Information Report - North St. Vrain and St. Vrain Creeks, Floodplain Update, Lyons, Boulder County, Colorado
• Date: 6/1/1998
• Designation Date: 7/1/1998
• Floodplain - Doc Type: Correspondence

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..~ A DAMES & "MC)ORE GROUP-coMPANY. -

June 12, 1998

RECEIVED
JUN 15 1998

Seventeenth Street Plaza
1225 Seventeenth Street
Suite 200
Denver, Colorado 80202
3032938080 Tel
303 293 8585 Fax

Mr. Larry Lang
Chief, Flood Control and Floodplain Management Section
Colorado Water Conservation Board
1313 Shennan Street, Room 721
Denver, CO 80203

CoI018do WlIIeI
Cons8lValion IloarlI

RE: North St. Vrain Creek & St. Vrain Creek Updated Flood Infonnation Report

Dear Mr, Lang;

In accordance with Section 37-60-106 (l)(c) c.R.S., as amended, the Town of Lyons is requesting the
Colorado Water Conservation Board consider the designation and approval of flood hazard areas within
the incorporated portions of the town, as depicted in the "St. Vrain Creek Floodplain Update", Flood
Infonnation Report for Lyons, Colorado, dated J1,Ine 1998.

The Floodplain Information Report contains floodplain infonnation for SL Vrain Creek & North SL Vrain
Creek that the Town believes is more current than the floodplain information contained in two reports
previously designated by the CWCR Those twO reports are entitled "Flood Insurance Study, Town of
Lyons, Colorado, Boulder County", dated p'ebruary 1980, and "Floodplain Information Report,
North St. Vrain & St. Vrain Creeks, Boulder County, Colorado", dated December 1987 (Engineering
Professionals, Inc.), A follow-up report, entitle(1 "Floodplain Re-Analysis and Floodway Delineation,
North St. Vrain and St. Vrain Creeks, Boulder County, Colorado", dated September 1992 (Love &
Associates, Inc,) provided further analysis and was used as the basis for this report, This report is based
on more current topographic infonnation, and 011 a more current and detailed hydraulic analysis than the
two previous reports designated by the CWCR In addition, it is based on a more current hydrologic
analysis (prepared by the U.S, Army Corps of Engineers) than the 1980 Flood Insurance Study.

We would like for CWCB staff to review this updated Floodplain Information Report dated June 1998 for
designation and approval at the CWCB's regular meeting scheduled for July 13 - 14, 1998, We would
also like for CWCB staff to compare the infonnation in the Floodplain Infonnation Report to the
infonnation in the 1987 Engineering Professionals, Ine. report, specifically related to unincorporated
portions 1)f Boulder County adjacent to Lyons, to assure consistency in floodplain inforrnation between
the town and the county. The prior designation of the 1987 report did not designate any areas that were in
the Town of Lyons as of January 19, 1989. Since 1989, certain areas that were fonnerly in
unincorporated Boulder County have been anneJled into the Town of Lyons as part of the designation of
the Floodplain Infonnation Report, We request that the CWCB rescind the prior designation of the 1980
Flood Insurance Study and those portions of the designation of the 1987 Floodplain Infonnation Report
that relate specifically to areas recently annexed to the Town of Lyons as part of the designation of the
1998 Floodplain Infonnation Report.

Please call me'at [phone] if you have questions about our request for designation and approval,

~~ ~. JL.LtJ

BRW, Inc.
Robert D. Krehbiel, PE
Town of Lyons Engineer

Offices Worldwide

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