FLOOD10415

• County: Conejos
• Stream Name: Alamosa River
• Title: Assessment Report on the Alamosa River, Between Terrace Reservior and Gunbarrel Road
• Date: 10/1/2002
• Prepared For: Alamosa River Watershed Restoration Project
• Prepared By: Black Creek Hydrology, LLC
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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Introduction

This document presents findings of an assessment of the Alamosa River between Terrace Reservoir and Gunbarrel

Road near Capulin, Colorado. The assessment was performed in order to visually determine and document the

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condition of the stream and b~s, note areas of apparent instability, erosion or deposition and to photograph typical
and/or severe problem locations and map those locations. In addition, this report presents possible mitigation strategies

and discusses potential effects of the stream's present condition on the proposed restoration of sections of river

downstream of Gunbarrel Road.

The assessment reach was walked over a period of three days by Steve Belz and Alan Miller, starting just below the

Terrace Reservoir dam, in early September 2002. During that period, flow released from Terrace Reservoir was

approximately ten to fifteen cubic feet per second. Recent rainfall in the upper Alamosa River watershed had increased

the turbidity of the flow in the upper two miles of the assessment reach.

During the assessment walk, numerous points along the river were photographed and located using a handheld GPS

receiver. These points were nVmbered and are shown on the map in Figure 1. Photographs of the channel, taken at the

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GPS points, are included in Appendix A. Each photograph is labeled with an identifier that indicates the film roll

number, the photograph number on that roll and the GPS point number. The GPS point number is the last number in
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each photograph identifier and corresponds to the point numbers shown on the map. Please note that, because the GPS

receiver was a handheld unit and the data was not post-processed, the positional accuracy is no better than about 30
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feet. Although the GPS point~ were located in the river channel, the mapped points do not always lie on the channel in

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Figure 1. The approximate loc;ttions of GPS point numbers 38 through 118 are also shown on aerial photographs in

Appendix B.

Information recorded during 1:l1.e assessment walk included documenting, photographing and rough measurements of

eroded banks. The approxima~e lengths and heights of all major actively eroding banks were recorded, the sites located

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with the GPS unit and photogr~phed.
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The GPS route points and map' in Figure 1 were used to detennine the river length of the assessment reach. The

distance from the Terrace Reservoir dam to Gunbarrel Road is about 55,000 feet (about 10.4 miles). For reference
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