The question addressed in this blog comes from a new PPIC report that calls for reforms in management of environmental water stored behind dams in California. The report shows it is possible to manage water in ways that are compatible with maintaining a natural ecosystem in streams below and above dams (Null et al. 2022). An appendix to this report focuses on fishes (Moyle et al. 2022). It provides information on how dams and reservoirs affect native fish populations and supports the need for improved water management to avoid future extinctions.