Modeled riparian plant community habitat suitability along the Colorado River in Grand Canyon in support of resource impact analysis for Post-2026 reservoir operational alternatives

These data were compiled in support of the Post-2026 Operational Guidelines and Strategies for Lake Powell and Lake Mead (Post-2026) Environmental Impact Statement (EIS). These data were used to illustrate how six operational strategies (one baseline and 5 alternatives) for Glen Canyon Dam could affect riparian plant communities along the Colorado River between Glen Canyon Dam and Lake Mead. The objective of this study was to quantify potential responses of specific vegetation metrics to those alternatives. Specifically, we predict suitable habitat for vegetation metrics from 2027 to 2060 under each alternative representing different Colorado River water management scenarios. The scenarios were implemented under 1200 possible hydrological futures per alternative. These data represent the estimated square meters of suitable habitat derived from niche modeling for 10 vegetation metrics in three stretches of river from 2027 to 2060. Riparian plant communities differ along the Colorado River and can be divided into three floristic regions associated with river segments: Marble Canyon, eastern Grand Canyon, and western Grand Canyon (Palmquist et al. 2018). Results were developed for each floristic region independently. The metrics are total vegetation, native species richness, proportion native species, as well as estimates for species and groups of species (Baccharis spp., Datura wrightii, marsh species, Phragmites australis subsp. americanus, Pluchea sericea, Prosopis glandulosa, and Salix exigua). These data were compiled by the U.S. Geological Survey Grand Canyon Monitoring and Research Center and Northern Arizona University by conducting Maximum entropy (Maxent) habitat suitability modeling for each of 44 long-term monitoring eddy sandbars. These data can be used to compare alternatives relatively in terms of more or less suitable habitat.