Colorado River Connectivity Channel
A New Channel for Fish and Sediment Passage
As part of the Windy Gap Firming Project’s permitting phase to build Chimney Hollow Reservoir, the historical impacts of the original Windy Gap Project were also evaluated, including the loss of river connectivity following construction of the Windy Gap Reservoir dam on the Colorado River. To minimize the dam’s impact on aquatic habitat and species, the Municipal Subdistrict, which owns and operates the Windy Gap Project, agreed to decrease the reservoir’s footprint and construct a connecting channel around the reservoir capable of passing water, fish and sediment, thereby reconnecting miles of the Upper Colorado and Fraser rivers.Colorado River Connectivity Channel Conceptual Design
The Colorado River Connectivity Channel project, which will also allow public access for fishing along most of the new channel, includes:
- Windy Gap Dam Embankment Modification - A new southern embankment will create a smaller reservoir and provide space to construct the new channel and floodplain. The spillway will also be modified to compensate for reduced reservoir storage.
- Diversion Structure - A new diversion structure will allow river flows to be diverted between the reservoir and new connectivity channel. The structure will allow sufficient flow into the reconfigured reservoir to meet pumping requirements when the Windy Gap Project’s water rights are in priority, while also maintaining downstream transport of water, sediment and the passage of fish.
- Connectivity Channel - A new channel and floodplain will connect the Colorado River above and below the reconfigured reservoir. To the extent possible, the new channel and floodplain will allow natural geomorphic and ecological river processes to take place while maintaining dam safety.
- Fraser Stream Gage Retrofit - Improvements to the Fraser River stream gauge immediately upstream of Windy Gap Reservoir will facilitate fish passage.
Multiple invested stakeholders are assisting to ensure a successful connectivity channel project. Stakeholder contributions include design, project management, fund raising and time. The Municipal Subdistrict and Trout Unlimited contracted with AECOM to conduct the final design. Other project partners include Colorado Parks and Wildlife, Colorado Water Conservation Board, Grand County, the Colorado River District and the Upper Colorado River Alliance.
In September 2020, Northern Water drained Windy Gap Reservoir, located on the Colorado River near Granby. This work allowed engineering crews to perform geotechnical studies on materials beneath the reservoir as part of the future connectivity channel project. The project is in final design as the stakeholders pursue permits and full approval to proceed with construction. Full approval and final permits are anticipated in summer of 2021. Due to the limited construction seasons in the area, crews intend to make use of the fall of 2021 to begin some construction activities, while the bulk of the construction efforts are scheduled to take place between the end of runoff and the start of the winter season in 2022 and 2023.