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 Mark West Creek watershed through the implementation of ten streamflow enhancement projects and to monitor key watershed characteristics over the 2021-2023 dry seasons. One objective of this project is to provide baseline data on streamflow, general water quality and late-summer wetted habitat conditions in critical coho and steelhead rearing reaches in order to document potential impacts of low flow on rearing salmonids and to demonstrate if and how stream conditions change with the implementation of the streamflow enhancement projects. This annual report describes the results of our streamflow and environmental monitoring activities for the 2021 summer season.