FLOOD08727

• County: Routt
• Community: Unincorporated Routte County
• Stream Name: Lower Elk River
• Basin: Yampa/White
• Title: 1997 Lower Elk River Flood Field Iinspection Report
• Date: 2/17/1998
• Prepared For: Routt County Unincorporated
• Prepared By: CWCB
• Floodplain - Doc Type: Flood Documentation Report

Colorado Water Conservation Board
Department of Natural Resources
721 Centennial Building
1 31 3 Sherman Street
Denver, Colorado 80203
Phone: [phone]
fAX, [phone]

STATE OF COLoRAbfs
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February 17, 1998

Roy Romer
Governor

Mr. William F. Horak, Jr.
District Chief
U.S. Geological Survey
P.O. Box 25046, MS 415
Denver, Colorado 80225

lames S. Lochhead
Executive Director, DNR

Dilries C. Lile, PE.
Director, ewes

RE: Elk River near Milner, Colorado

Dear Mr. Horak:

The Flood Control and Floodplain Management Section of the Colorado Water Conservation
Board (CWCB) requests that the U.S. Geological Survey (USGS) conduct an investigation and
make a determination of an official peak streamflow for the Elk River gage near Milner,
Colorado for June 3, 1997.

The significant runoff event on the Elk River in June of 1997 necessitated some evacuations and
caused damage to public and private property to the north of State Highway 40 in Routt County.
A number of interested parties have been involved with this flood issue including local
landowners, the Lower Elk River Flood Association, Routt County officials, Colorado State
Representative Jack Taylor, the CWCB, the Colorado Department of Transportation, and others.

Preliminary results obtained from Dr. Robert Jarrett of the USGS indicated that the gaging
station on the Elk River near Milner may not have accurately recorded the peak flow due to the
high stage and unrecorded flows in the overbank of the river. Based on preliminary fieldwork,
Dr. Jarrett estimated that approximately 400 cfs bypassed the gage. The CWCB concurred that
as much as 10% of the flow was lost in the overbank and bypassed the stream gage. Dr. Jarrett
indicated a total peak flow of 6,600 cfs (6,200 gaged and 400 cfs bypass) for the June 3 flood
event. Based on a tape-down measurement at the Milner gage, Dr. Jarrett flagged the event as
the flood-of-record having a greater than 100-year flood frequency. (It is my understanding that
Mr. Mark Smith of the USGS had made plans to perform field investigations on the Elk River to
follow up with Dr. Jarrett's work. An unfortunate flash flood in Fort Collins created an
enormous workload for Mr. Smith and thus prevented him from actually visiting the Elk River.)

A letter from the Regulatory Branch of the Corps of Engineers (Corps), dated January 6, 1998,
regarding hydrology issues on the Elk River was received by the CWCB. According to the
letter, Mr. Rich Carver and Mr. Rick Crowfoot of the USGS indicated that the stream gage on
the Elk River near Milner estimated a peak flow of 5,370 cfs on June 3, 1997. This flow was