Integrating monitoring and optimization modeling to inform flow decisions for Chinook salmon smolts

•We illustrate how estimates from disjunct monitoring data can be used to inform adaptive water management.•Larger may flow pulses than are currently being allocated are projected to be optimal for increasing Chinook salmon smolt survival through the south delta.•Water temperature and smolt outmigration timing drive optimal water distribution but sensitivity analysis indicates water allocation changes little with temperature uncertainty indicating future monitoring should focus on outmigration timing.•We suggest using current data to start informing decisions for complex problems despite far from perfect knowledge about system responses.