Healthy aquatic, riparian, and floodplain ecosystems require periodic high flow events, not just minimum flows. In managed systems, high flows can be provided at appropriate times of year and at frequencies to support dependent systems and processes. Streams and rivers support riparian vegetation, a specialized assemblage of plants that is adapted to and relies upon certain ranges of geomorphic and flow conditions. For example, natural cottonwood tree recruitment occurs when there is a gradual decline in the relative elevation of a river and its associated hyporrheic flow, but not if the decline is too rapid, as can accompany managed systems. Movement and re-distribution of sediment downstream, channel migration, bank erosion, and new land formation are all important functions of in-stream flows. These geomorphic processes are supported above certain flows in a natural system and can be mimicked to some degree in managed systems. This indicator is used in the Sacramento River Riparian Monitoring and Assessment Program, as well as other similar large-river systems.