Streamflow characteristics offer some of the most appropriate and useful indicators for assessing watershed health. They are extremely sensitive to human activities and reflect weather and climate conditions, vegetation and soil type, land characteristics, and human use. Common human activities, such as increasing the number of roads and parking lots, change the timing and strength of runoff events resulting in "flashy" systems. Such hydrologic variation shapes the biotic diversity within stream ecosystems by controlling critical habitat conditions.
The San Francisco Bay Area Inventory and Monitoring Program monitors streamflow at stations within Golden Gate National Recreation Area, Point Reyes National Seashore, and Pinnacles National Park. Primary monitoring tasks at these stations include obtaining stream discharge measurements and capturing low-flow conditions as well as peak flow. These tasks are conducted monthly throughout the year and during winter storms in order to establish a calculated relationship between water level and discharge for each stream.