Trends in the Outcomes, Practice, and Law of Low-Tech Process-Based Restoration in Western Rangelands

Low tech process-based restoration (LTPBR) is increasingly used to improve river corridor resilience to diverse stressors introduced by changing land use, climate, and water usage. However, the future of LTPBR depends on multiple physical, ecological, and social factors, including the influence of water availability on LTPBR outcomes and the legal capacity for future restoration in water-limited environments. A growing body of scientific and legal literature on LTPBR allows for a quantitative, regional comparison of LTPBR projects to understand: (1) How do physical characteristics of LTPBR projects (including structure type, number, and local setting) influence the magnitude of change following LTPBR? and (2) How are social dimensions related to practitioner attitudes and water law impacting LTPBR? We evaluated data from 65 LTPBR projects in the western U.S. that used natural beaver dams, beaver dam analogues, or one-rock dams to quantify trends in commonly measured outcomes with geographic location, project size, and local precipitation. We additionally reviewed water law in five states across the western U.S. and interviewed 13 restoration practitioners to consider the social dimensions of LTPBR. Results show that LTPBR projects significantly increased water storage, sediment storage, and riparian vegetation greenness, and that outcomes vary significantly with mean annual precipitation, time since restoration, and LTPBR type. Trends suggest that LTPBR could provide expected outcomes across western rangelands even amid changing water availability. Changes to state-level water laws and perceptions of social benefits of LTPBR could support the expansion of stream restoration in rangeland streams. More monitoring and collaborations are needed to better implement, manage, and understand LTPBR projects and outcomes.