FLOOD02750

• Document ID: 125
• County: Routt
• Stream Name: Elk River
• Basin: Yampa/White
• Water Division: 6
• Title: Streambank Stabilization Limited Watershed
• Date: 11/1/1999
• Prepared For: CWCB
• Prepared By: ICON Engineering, Inc.
• Watershed Pro - Doc Type: Educational/Technical/Reference Information

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SECTION 1
INTRODUCTION

1.1 PURPOSE

The purpose of this study was to perform a limited investigation of the Elk River watershed
hydrology, and to address stream stabilization measures along the lower 0.9 mile of the Elk
River. This area was subjected to severe flooding in 1997. While this report will not
specifically address flooding issues, the basic flood hydrology will be established. The primary
focus of the study is to complete hydraulic analyses, and use the results to complete conceptual
level engineering design of bank stabilization alternatives with quantity and construction cost
estimates. The work is authorized under Section 37-60-106(l)(c) of the Colorado Revised
Statutes,

1.2 _ PROJECT LOCATION AND BACKGROUND

The Elk River is located in north-central Colorado (Figure 1.1), Steamboat Springs is located
approximately 8 miles to the east of the mouth of the Elk River at its confluence with the
Yampa River. The study area is in Routt County. A north bank tributary to the Yampa River,
the Elk River flows primarily south out of Routt National Forest on the western side of the
Continental Divide. The eastern portion of the basin originates within the Park Range and is
partly within the Mount Zirkel Wilderness area, The Elk River confluence with the Yampa
River is downstream of the Denver & Rio Grande Western Railroad and U,SAO (D,S, 40)
bridges.

Property along the lower Elk River is owned by a number of different interests. Figure 1.2
illustrates property ownership information in the vicinity of the study reach.

1.3 DATA COLLECTION AND FIELD INVESTIGATION

The field investigation in support of this study included a site visit by ICON Engineering. Inc.
(ICON) to obtain the following information:

. Identify areas of bed level changes including incising and aggradation;
. Locate and characterize areas of significant bank erosion;
. Estimate channel and overbank roughness relative to flow resistance;
. Identify natural and manmade controls within the study reach;
. Verify existing structures;
. Observe general drainageway characteristics and geomorphic floodplain features to
assist with individual reach identification;
. Verify outlet works and operation practices for Steamboat Lake,

A variety of data was collected in addition to that provided from the field investigation,
Streamflow gage data for the Willow Creek below Steamboat Lake gage was obtained from the
State of Colorado Division of Water Resources. Streamflow information and gage data were
obtained from the U.S, Geologic Survey (USGS) for the Elk River at Milner, Clark and Above
Clark gage sites, The Natural Resource and Conservation Service (NRCS) provided data from
their SNOTEL gage in the Elk River basin, as well as soil survey information along the study

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