Environmental flows (e‐flows) are powerful tools for sustaining freshwater biodiversity and ecosystem services, but their widespread implementation faces numerous social, political, and economic barriers. These barriers are amplified in water‐limited systems where strong trade‐offs exist between human water needs and freshwater ecosystem protection. We synthesize the complex, multidisciplinary challenges that exist in these systems to help identify targeted solutions to accelerate the adoption and implementation of environmental flows initiatives. We present case studies from three water‐limited systems in North America and synthesize the major barriers to implementing environmental flows. We identify four common barriers: (a) lack of authority to implement e‐flows in water governance structures, (b) fragmented water governance in transboundary water systems, (c) declining water availability and increasing variability under climate change, and (d) lack of consideration of non‐biophysical factors. We then formulate actionable recommendations for decision makers facing these barriers when working towards implementing environmental flows: (a) modify or establish a water governance framework to recognize or allow e‐flows, (b) strive for collaboration across political jurisdictions and social, economic, and environmental sectors, and (c) manage adaptively for climate change in e‐flows planning and recommendations. This article is categorized under: Water and Life > Conservation, Management, and Awareness Human Water > Water Governance Engineering Water > Planning Water

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Population declines and local extirpation trends are widespread among freshwater species, but the responsible drivers of these trends are poorly understood. Identifying the potential drivers of population declines is essential to effective conservation planning. However, conventional detection methods used to monitor cryptic and elusive freshwater species are inefficient. Integrating new surveying and modelling techniques may allow for a more comprehensive assessment of population declines. We used environmental DNA (eDNA) sampling methods and detailed historical records to identify drivers of local extirpation in a declining, long‐lived giant salamander, the eastern hellbender (Cryptobranchus alleganiensis alleganiensis) in West Virginia, U.S.A. We used a site occupancy and detection modelling framework (SODM) to test the influence of current land use, historical mining, hydrogeomorphic and water quality variables on model‐based predictions of hellbender extirpation and detection. We failed to detect hellbender eDNA at 51% (naïve 1 – Ψ) of historical sites, suggesting local extirpation at a broad spatial scale in West Virginia. Our best‐supported SODM model suggested catchment‐scale road density was the best predictor of hellbender extirpation, and that 38% (predicted 1 – Ψ) of historical sites may be locally extirpated. Estimates of hellbender occupancy probability were extremely low in highly developed catchments. Water turbidity and conductivity were the best predictors of eDNA detection, both negatively influencing detection probability. Roads can increase sedimentation rates and alter water chemistry of freshwater ecosystems, identifying landscape alteration/human development and water quality declines as possible drivers of hellbender extirpation trends in West Virginia. Our findings also suggest that water conductivity and turbidity may act as polymerase chain reaction inhibitors and decrease eDNA detection in lotic systems. This study emphasises the negative impacts of urban development on freshwater ecosystems and the sensitivity of long‐lived amphibian species to rapid environmental change. Our findings may aid in conservation planning by providing a sampling framework that integrates eDNA data within a SODM framework to rapidly and accurately assesses relational changes in aquatic species' occupancy at historical sites.

Effective conservation planning relies on accurate species detection. However, conventional sampling methods used for detecting rare and cryptic aquatic species suffer from low probabilities of detection. Environmental DNA (eDNA) has emerged as an innovative and powerful sampling tool for detecting aquatic species, with previous studies suggesting a detection advantage over conventional sampling. However, comparative studies often fail to consider the appropriate sampling frameworks to adequately compare sampling methodologies and account for the influence of environmental variables on eDNA detection probabilities. In this study, we paired two detection methods (eDNA and physical sampling) at 22 sites in West Virginia, USA, to compare the probability of detecting a cryptic, elusive, and imperiled species of giant salamander, the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis). We used a multimethod occupancy modeling framework to compare method-specific detection probabilities using a suite of predictor variables based on environmental conditions thought to influence hellbender detection. We detected hellbenders at 19/22 sites using eDNA and at 13/22 sites using physical sampling methods. The best supported model indicated that detection probability for eDNA (0.84 ± 0.06) was three times higher than conventional methods (0.28 ± 0.07). Water turbidity was the best predictor of hellbender detection and negatively impacted our ability to detect eDNA. We failed to detect an association between eDNA concentration and hellbender catch per unit effort. Our study supports previous findings that suggest eDNA sampling methods greatly increase the probability of detecting aquatic species. However, with little known about the influence of environmental variables on eDNA detection, our results highlight the negative influence turbidity and other physiochemical factors have on eDNA detection and suggest that further research on eDNA detection in turbid environments is needed. | 87 WINELAND Et AL.