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Willow Creek Reclamation Committee <br />Windy Gulch Project Final Report <br />PROJECT BACKGROUND <br />Willow Creels is a tributary of the upper Rio Grande River in Southwestern Colorado near <br />Creede, Colorado in Mineral County. The Willow Creels Reclamation Committee (WCRC) is a <br />community-based watershed group with the mission to improve water quality and habitat, reduce <br />flood risks, reclaim areas impacted by mining, and preserve historic struct<ires in the Willow <br />Creek watershed. The WCRC has sought to revitalize stream corridors that have been degraded <br />by a century of contamination, sediment deposition, and maiupulation. Flood control and stream <br />restoration is a high priority for the associated communities of Creede and Mineral County, and <br />the WCRC has worked on the design and funding for large scale projects above and below town. <br />Windy Gulch is one of three prominent tributaries to Willow Creek. The Windy Gulch <br />knprovement Project addresses the confluence of Windy Gulch with Willow Creek at the north <br />end of Creede. This project is one component in our objective to restore functionality, aesthetics, <br />and flood control in the Willow Creek watershed. The goals of the Windy Gulch project were to <br />help protect downtown Creede from flooding by Windy Gulch and Willow Creek, and also to <br />improve stream stability in Windy Gulch and Willow Creek during high flow events. <br />Windy Gulch passes under the Bachelor Loop road and enters Willow Creek just upstream of the <br />mortar and rock flume that conveys Willow Creek through Creede. Prior to the project, the <br />culvert under the Bachelor Loop road was a 2.5 ft high by 4 ft wide elliptical, corrugated metal <br />culvert. Water Management Consultants (for Homestake Mining Company 2002) estimated <br />flood levels in Windy Gulch using arainfall/n~noff model and estimated that a 100-year flood <br />would produce 239 cfs. The value was considered potentially high, but the most accurate, by <br />Agro Engineering's flood control study of upper Willow Creek fiuided through the CWCB <br />(2002). Using Water Management Consultants hydrology, Agro Engineering found that the <br />current culvert would be overtopped during flood events iiutiating at the 10-year level. A portion <br />of the floodwaters overtopping the culvert would flow south towards downtown Creede, and a <br />flood exceeding the culverts capacity could also cutoff access to Creede's Fire Station just north <br />of the culvert. The risk of flood damage to historic downtown Creede, and the importance of <br />emergency service from the fire station during flood events necessitated improvements. <br />Agro Engineering's flood control study also identified that a small portion of the levees around <br />the forebay to the Creede flume near Willow Creek did not have a full aft freeboard when flood <br />levels in Willow Creek were modeled. Current FEMA floodplain mapping shows much of <br />downtown Creede in the 100-year floodplain delineation. The FEMA floodplain mapping was <br />not updated to reflect installation of the Creede flume in the 1950s. Modeling by the NRCS has <br />indicated that the flume does have sufficient capacity to carry a 100-year flood (although there <br />are concerns of structural capability). To enable the potential removal of downtown Creede from <br />the 100-year FEMA floodplain mapping, the small portion of levee needed to be raised to a full 3 <br />ft freeboard as required. <br />Therefore, the Windy Gulch Improvement Project was proposed to replace the Windy Gulch <br />culvert with a culvert with capacity to pass a 100-year flood and to ensure that the flume forebay <br />levees had a full 3' freeboard above 100-year flood levels. <br />