About the Wild Horse Reservoir Project
The Wild Horse Reservoir Project is a proposal from Aurora Water to build a new off-channel reservoir southwest of Spinney Mountain Reservoir near Hartsel, Colorado, in Park County. The new reservoir would provide the critical water storage that Aurora Water needs to ensure reliable water supply for community needs and maintain emergency water reserves.
The proposed Wild Horse Reservoir Project is part of Aurora Water’s comprehensive, long-term plan and forward-thinking, multi-pronged approach to meeting our community’s water needs. The additional water storage provided by the Wild Horse Reservoir Project would help store some of the water saved from Aurora Water’s ongoing water conservation and reuse initiatives.
UPDATE: During evaluation of the alternative locations, Aurora Water identified the Wild Horse South Reservoir alternative as the site to advance for further environmental review and permitting processes. Key considerations include fewer dams (one versus three), lower operational and construction risks, no additional pumping required to fill the reservoir, and minimal wetland impacts. It also allows Aurora Water to source materials for the project from existing Park County quarries, to support local businesses. This avoids the need to develop a new quarry site, thereby minimizing additional land disturbance. Learn more about this announcement.
Map of Wild Horse Reservoir Project alternatives. Click the image to view a larger image.
The locations evaluated for the Wild Horse Reservoir Project alternatives were identified within the South Platte River basin to ensure that stored water can be accessed during emergency conditions. The potential sites are also located near the Otero pipeline, which currently conveys about half of Aurora’s water supply from the Colorado and Arkansas Rivers to Spinney Mountain Reservoir. Thus, these locations not only provide access to emergency storage, but also allow for efficient integration with Aurora Water’s existing water supply system. Learn more about how the Wild Horse Reservoir Project would work.
Aurora Water engaged Park County officials early in the process to ensure open communication and collaborative planning. Since then, Park County and Aurora Water have continued working together to evaluate options and share information with the South Park community.
Aurora Water has considered various environmental factors as we have prepared, planned, and designed the proposed Wild Horse Reservoir Project:
- Water would be provided via pipelines, so the reservoir would be off-channel. This means the project would not have dams blocking any existing rivers or streams.
- Water for the project would be supplied from existing water rights, so no new water rights or decrees would be required.
- Initial modeling has shown that there are no significant streamflow impacts to the South Platte, Colorado, or Arkansas rivers.
- The high-altitude location and the proposed depth of the Wild Horse Reservoir Project means less water evaporation.
- Aurora Water’s initial studies have not identified any threatened or endangered species at the Wild Horse South Reservoir site.
- The grassland location reduces the risk of wildfire in the immediate vicinity.
- The project could create additional wildlife habitat to complement the existing grasslands.
The Wild Horse Reservoir Project is currently in the planning and pre-permitting phase. Aurora Water is conducting design and field work to prepare for the required federal, state, and county environmental reviews and permitting processes.
- The Bureau of Land Management (BLM)—as the lead federal agency—will manage the federal National Environmental Policy Act (NEPA) review process. Learn more about the NEPA process.
- The Colorado Department of Public Health and Environment (CDPHE) will be managing review of environmental impacts to wetlands and streams under Regulation 87—Dredge and Fill. Learn more about the state review processes.
- Park County officials will be managing review of the project under the county’s 1041 regulations. Learn more about the county review process.
For more information on these and other environmental reviews and permitting processes, see the Project Review and Permitting webpage.
Wild Horse Reservoir Project Alternatives
In preparation for the environmental review process required by the National Environmental Policy Act (NEPA), the Bureau of Land Management (BLM) identified a set of alternatives for in-depth analysis.
- Wild Horse Reservoir
- Wild Horse South Reservoir (Aurora Water identified this alternative as the site to advance for further environmental reviews and permitting processes.)
- Small Wild Horse Reservoir + Denver Basin Aquifer Storage and Recovery (ASR)
- Spinney Mountain Reservoir Enlargement (BLM removed from further evaluation as of February 2026.)
- No Action Alternative—Denver Basin ASR
Wild Horse Reservoir Project Alternatives Map
Click to view a larger version of the project alternatives map.
