California Natural Flows Database
The Sustainable Groundwater Management Act requires that impacts to beneficial users of groundwater and surface water be considered when establishing sustainable management criteria for interconnected surface waters. Groundwater Sustainability Agencies interested in establishing measurable objectives that can protect instream flow needs can now access the California Natural Flows Database—a new tool predicting natural flows across California. These predictions include monthly flow and functional flow metrics that represent aspects of the annual flow variation that directly relate to ecological, geomorphic, or biogeochemical processes in rivers and streams (e.g., wet-season peak flow, dry-season base flow). The functional flow metric predictions are part of the California Environmental Flows Framework (CEFF), a statewide approach to develop stream segment-scale ecological flow criteria that protect native aquatic species and communities. Functional Flow metric predictions are currently in draft form and have not yet been peer-reviewed. We will update this site with a link to documentation when peer review has been completed. The estimates of natural functional flow metrics are from a statewide model trained using observed values from 219 reference gauges across the state. Given the diversity of landscapes and stream conditions in California, the accuracy of metric estimates is expected to vary based on the physical setting of individual streams. Users should consider local circumstances when interpreting the data and refer to the California Environmental Flows Framework for additional guidance.