Identifying gaps in protected areas to expand integrated riverine ecosystem conservation

As demand for water in the arid southwest increases, pressure is mounting on many aquatic and riparian species that rely on riverine habitat for survival. Some of these riverine areas are managed as private, state, or federal lands with differing levels of mandated protections; however, few efforts have explored the potential of filling gaps in riverine protection afforded by designation under the protection of the Wild and Scenic Rivers Act (WSRA) of 1968. Here, we examine how inclusion of eligible rivers, specifically the Nationwide Rivers Inventory (NRI), could fill gaps in protection for a species of high conservation need. A gap analysis overlapping the predicted species range with human disturbances and the level of protection identifies where sufficient protections for a species exist and where there are shortcomings, that is, gaps, potentially addressed by elevating NRI reaches to WSRA protection. This study uses the narrow-headed garter snake as an indicator species for riverine ecosystem health of free-flowing perennial reaches within the Arizona/New Mexico Mountains EPA Level III ecoregion. Over a quarter of NRI-eligible reaches within the ecoregion are within the protection gap for the narrow-headed garter snake. If designated Wild and Scenic, these reaches could offer needed protection for this species.