Agro Engineering, Crop Consulting and Water Resource Specialists

UPPER WILLOW CREEK FLOOD CONTROL AND STREAM RESTORATION STUDY
Willow Creek Reclamation Committee/Colorado Water Conservation Board

Agro Engineering, Inc. was selected by the Willow Creek Reclamation Committee and Colorado Water Conservation Board to prepare a flood control and restoration plan for Upper Willow Creek in southwestern Colorado. Upper Willow Creek, which includes East and West Willow Creeks, flows through the historic Creede mining district in the San Juan Mountains of southwestern Colorado prior to flowing into the Rio Grande River. The town of Creede and numerous historic mining areas are located within the Willow Creek floodplain. The stream has been impacted significantly by historic mining practices.

The primary goal of the project is to quantify the risk of flooding within the area and develop approaches to reduce the risk of flooding and property damage from Upper Willow Creek, control debris and sediment problems associated with the Willow Creek watershed, and improve the aesthetic qualities, habitat conditions, and physical functioning of the stream. The study was divided into phases for analysis of problems, development of mitigation strategies, and prioritization and development of an implementation plan.

In the problem analysis phase, Agro Engineering surveyed area topography and developed a comprehensive hydraulic model using the Army Corps of Engineers HEC-RAS model. Over three miles of the stream were modeled with 104 cross-sections and numerous hydraulic structures. Flood inundations were delineated and the risk of flooding was evaluated throughout the reach. Potential sediment transport rates were also evaluated within the reach using information from the hydraulic analysis. In addition, Agro Engineering developed aerial photo mosaics to identify sediment sources within the watershed and evaluate the sediment production potential of watershed areas using GIS.

After identifying potential problem areas, a list of appropriate mitigation strategies was developed. These strategies include replacement of culverts, small extensions of levees, construction of a flood bypass around mine tailings, construction of sedimentation and debris basins, watershed sediment source controls, channel enhancements using vortex weirs and willow plantings, and reshaping and restoration of a stream reach. TEC MEMO 2, a draft report detailing these projects can be downloaded here as a .pdf document.

These mitigation projects will be prioritized and an implementation plan will be developed in coordination with the Willow Creek Reclamation Committee.