UC Merced

The construction and operation of dams, reservoirs, hydropower plants, and water diversion infrastructure has significantly altered riverine ecosystems by disrupting natural hydrologic, geomorphic and ecological processes. These facilities release environmental flows to prevent and mitigate their negative impacts. Environmental flows implementation has advanced in recent decades through the development of the functional flows and active management paradigms, as well as an increasing emphasis on responsiveness to hydroclimatic variability. In order to facilitate the adoption of these modern approaches, this study establishes a baseline understanding of the extent to which these principles are currently being utilized, as well as the attitudes of facility operators regarding this topic. An online survey is used to solicit information from operators of hydropower facilities in the Western United States. We received 63 valid responses from 447 emailed survey invitations, yielding a 14 percent completed response rate. Descriptive and exploratory data analysis techniques were used to obtain insights. Results indicate that the regulatory framework and objectives for environmental flows are grounded in the protection of targeted species, especially fish. Respondents report widespread usage of traditional environmental flows techniques that are simple, static, non-collaborative, and reactive. The application of modern advances in environmental flows may be hindered by inadequate stakeholder consultation, infrastructure, and regulatory frameworks, as well as pressure to deliver for competing operational objectives (especially hydropower) after satisfying the minimum environmental regulatory requirements. Operators indicate general belief in climate change and approval towards current environmental flows regimes, yet a significant minority do not conceptualize climate change as impacting their local region or their ability to implement environmental flows in the future. Lastly, hydrologic basin and facility size may have associative relationships with the extent of environmental flows implementation. This study contributes to the body of interdisciplinary knowledge that aims to guide the siting and reoperation of river facilities for optimized ecosystem health, hydropower, and other benefits.