Streamwater dissolved oxygen (DO) concentrations are driven by interacting physical and biotic parameters. Future DO depletion events in small, coastal salmon streams are therefore likely to be driven by changes in hydrology in addition to atmospheric warming. We measured DO, temperature, discharge and spawning salmon abundance in upstream (reference reach) and downstream salmon bearing reaches of four streams in southeast Alaska to determine how multiple physical and biotic factors interact to control streamwater DO. Stream temperature ranged from 5.1 to 15.8 °C and fell within the optimum range that is considered favorable for salmon physiology. Concentrations of DO ranged from 2.8 to 12.3 mg/L, with concentrations significantly [...]