Framework / Assessment California Forests and Rangelands: Proposed Indicators Summary To track water courses that are unimpaired by dams and barriers and available for fish passage. The status of stream impairment can change, for instance if a dam is removed. Other streams may have natural barriers, such as waterfalls, landslides or large boulders. The Passage Assessment Database inventories potential barriers to fish and can be used to track impaired and unimpaired streams throughout California’s forest and rangeland.