In April 2020, Trout Unlimited, California Sea Grant’s Russian River Salmon and Steelhead Monitoring Program and Sonoma Resource Conservation District were awarded a Wildlife Conservation Board (WCB) grant to enhance streamflow in the Mill Creek watershed, tributary to the Russian River, Sonoma County. This project includes collecting baseline data on streamflow, water quality and wetted habitat conditions in critical coho salmon and steelhead rearing reaches from the summers of 2021-2024 in order to document potential impacts of low summer flow on juvenile salmonids and to demonstrate how stream conditions change with the implementation of streamflow enhancement projects. This report describes the results of our summer 2021 streamflow and environmental monitoring activities.