A Finding of No Significant Impact (FONSI) for the Salt Wash Rehabilitation Project in Arches National Park was signed by the Acting Intermountain Regional Director on December 21, 2017. This decision was reached after reviewing the environmental impacts analyzed and considering public comments on the Environmental Assessment (EA) released in October.
The EA identifies strategies for reducing the frequency of flooding-related closures of the Wolfe Ranch/Delicate Arch Road by improving the flow of water and sediments.
Major components of this project include mechanical excavation and sediment removal from Salt Valley Wash, Salt Wash, and Winter Camp Wash, and mechanical removal of 54 acres of invasive tamarisk.
Flooding-induced road closures of the Wolfe Ranch/Delicate Arch Viewpoint road have increased in frequency and duration in recent years. All 15 culverts installed under the road at the three wash crossings have filled in with sediment and are non-functional.
Closing the flooded road, assisting stranded visitors, and removing sediment and debris have required more substantial efforts by park staff, and inconvenienced scores of park visitors. Road closures often last several days, preventing many visitors from accessing Delicate Arch, the most famous natural feature in the park.
Tamarisk is a non-native shrub that is extremely invasive in riparian communities, nearly completely replacing native vegetation with impenetrable thickets in many areas. Increased tamarisk cover in the Wolfe Ranch/Delicate Arch Viewpoint areas has clogged wash channels, exacerbated problems of sediment accumulation, and interfered with the natural flow of water.
During this project, sediment removed from the wash channels will be disposed of on-site in large sediment deposit areas selected to avoid impacts to native vegetation. Park staff will monitor these sites and treat any non-native plants that may appear as a result of the wash sediment introduction. Native seed mixes will be used on the sediment deposit sites to support growth of native plant species.
Project activities will take place from January 2018 through March 2018 and from September 2018 through March 2019.
Operating heavy machinery in the delta and wash channels will have visual and sound impacts during the project. These impacts will mostly be seen and heard by visitors at the Delicate Arch parking area and along the Delicate Arch trail. No road, parking area, or trail closures will occur as a result of this project.
The signed Salt Wash Rehabilitation Project FONSI may be viewed online at: https://parkplanning.nps.gov/saltwashproject_FONSI.